AMERICAN MOBILE SATELLITE CORP
10-Q, 1998-05-15
COMMUNICATIONS SERVICES, NEC
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-Q
             QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                  For the quarterly period ended March 31, 1998
                         Commission file number 0-23044

                      AMERICAN MOBILE SATELLITE CORPORATION
             (Exact name of registrant as specified in its charter)

                           DELAWARE          93-0976127
                     (State or other       (I.R.S. Employer
                     jurisdiction of      Identification No.)
                     incorporation or
                      organization)

                10802 Parkridge Boulevard
                        Reston, VA            20191-5416
                  (Address of principal       (Zip Code)
                    executive offices)

                                 (703) 758-6000
                         (Registrant's telephone number,
                              including area code)


     Indicate  by check mark  whether the  registrant  (1) has filed all reports
required to be filed by Section 13 or 15(d) of the  Securities  Exchange  Act of
1934  during  the  preceding  12 months  (or for such  shorter  period  that the
registrant  was  required to file such  report(s)),  and (2) has been subject to
such filing requirements for the past 90 days. Yes X No

     Number of shares of Common Stock outstanding at April 30, 1998: 30,582,782




<PAGE>




                          PART I-FINANCIAL INFORMATION

                          Item 1. Financial Statements

             AMERICAN MOBILE SATELLITE CORPORATION AND SUBSIDIARIES
                    CONSOLIDATED CONDENSED STATEMENTS OF LOSS
                      (in thousands, except per share data)
                                   (Unaudited)
<TABLE>
<CAPTION>

                                                             1998          1997
                                                             ----          ----
REVENUES
<S>                                                      <C>           <C>   
         Services                                          $6,418        $4,153
         Sales of equipment                                 3,604         4,532
                                                           ------        ------

         Total Revenues                                    10,022         8,685

COSTS AND EXPENSES:
         Cost of service and operations                     7,728         8,873
         Cost of equipment sold                             3,881         5,442
         Sales and advertising                              3,022         3,221
         General and administrative                         3,631         4,868
         Depreciation and amortization                     10,163         9,937
                                                           ------         -----

         Operating Loss                                   (18,403)      (23,656)

INTEREST EXPENSE                                           (6,638)       (4,370)
INTEREST AND OTHER  INCOME                                    141           945
EQUITY IN LOSS OF AMRC                                       (342)           --
                                                           ------        ------

NET LOSS                                                 ($25,242)     ($27,081)
                                                         =========     =========

BASIC AND DILUTED LOSS PER SHARE OF COMMON STOCK           ($1.00)       ($1.08)


WEIGHTED-AVERAGE COMMON SHARES                             25,241        25,109
         OUTSTANDING DURING THE PERIOD (000's)

See notes to consolidated condensed financial statements.
</TABLE>


<PAGE>



                          PART I-FINANCIAL INFORMATION
                    Item 1. Financial Statements (continued)
             AMERICAN MOBILE SATELLITE CORPORATION AND SUBSIDIARIES
                      CONSOLIDATED CONDENSED BALANCE SHEETS
                                 (In thousands)
                                   (Unaudited)
<TABLE>
<CAPTION>

                                                       March 31,    December 31,

ASSETS                                                     1998         1997
                                                           ----         ----

CURRENT ASSETS:
<S>                                                      <C>          <C>   
  Cash and cash equivalents                               $21,279       $2,106
  Inventory                                                38,554       40,321
  Accounts receivable-trade, net                           11,477        8,140
  Restricted cash-current portion                          41,038          --
  Prepaid in-orbit insurance                                2,889        4,564
  Other current assets                                     21,288        9,608
                                                          -------       ------
  Total current assets                                    136,525       64,739

PROPERTY AND EQUIPMENT - NET                              264,261      233,174

GOODWILL                                                   67,616           --

DEFERRED CHARGES AND OTHER ASSETS-NET                      34,164       13,534

RESTRICTED CASH - NON-CURRENT                              82,962           --
                                                          -------      -------

  Total assets                                           $585,528     $311,447
                                                         ========     ========

LIABILITIES AND STOCKHOLDERS' EQUITY

CURRENT LIABILITIES:                                          
  Accounts payable and accrued expenses                    28,042      $35,861
  Obligations under capital leases due within one year      4,133          798
  Current portion of long-term debt                        21,932       15,254
  Other current liabilities                                 7,626        7,520
                                                          -------      -------
  Total current liabilities                                61,733       59,433

LONG-TERM LIABILITIES:
  Obligations under Bank Financing                        100,000      198,000
  Obligations under Senior Notes, net                     326,510           --
  Capital lease obligations                                12,005        3,147
  Net assets acquired in excess of purchase price           2,550        2,725
  Other long-term debt                                      1,126        1,364
  Other long-term liabilities                                 610          647
                                                          -------      -------

  Total long-term liabilities                             442,801      205,883
                                                          -------      -------

  Total liabilities                                       504,534      265,316
                                                          -------      -------

STOCKHOLDERS' EQUITY:
  Preferred Stock, par value $0.01:   no shares issued         --          --
  Common Stock, voting, par value $0.01                       317          252
  Additional paid-in capital                              501,757      451,892
  Common Stock purchase warrants                           62,547       36,338
  Unamortized guarantee warrants                          (39,621)     (23,586)
  Retained loss                                          (444,006)    (418,765)
                                                         ---------    ---------
  Total stockholders' equity                               80,994       46,131
                                                         ---------    ---------

  Total liabilities and stockholders' equity             $585,528     $311,447
                                                         ========     ========

See notes to consolidated condensed financial statements.
</TABLE>



<PAGE>




                          PART I-FINANCIAL INFORMATION

                    Item 1. Financial Statements (continued)

             AMERICAN MOBILE SATELLITE CORPORATION AND SUBSIDIARIES
                 CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS
                                 (in thousands)
                                   (Unaudited)

<TABLE>
<CAPTION>

                                                                         Three Months Ended
                                                                               March 31
                                                                      ------------------------

                                                                            1998       1997
                                                                            ----       ----

CASH FLOWS FROM OPERATING ACTIVITIES:
<S>                                                                      <C>       <C>        
Net loss                                                                 ($25,242) ($27,081)  
Adjustments to reconcile net loss to net cash used
in operating activities:
  Amortization of guarantee warrants, debt discount and issuance costs      2,524     1,754
  Depreciation and amortization                                            10,163     9,937
  Equity in loss from AMRC                                                    342        --
  Changes in assets and liabilities:
     Inventory                                                              1,986    (3,483)
     Prepaid in-orbit insurance                                             1,675     1,693
     Trade accounts receivable                                              3,744    (1,480)
     Other current assets                                                    (661)    1,051
     Accounts payable and accrued expenses                                (12,197)   (9,070)
     Deferred trade payables                                                6,436        --
     Deferred items - net                                                     293       (37)
                                                                          --------  --------
Net cash used in operating activities                                     (10,937)  (26,716)

CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property and equipment                                        (1,126)   (3,574)
Acquisition of ARDIS                                                      (51,382)       --
Purchase of restricted cash securities                                   (123,000)       --
Purchase of interest swap agreement                                       (17,892)       --
Investment in AMRC                                                             --    (3,000)
                                                                         ---------   -------
Net cash used in investing activities                                    (193,400)   (6,574)

CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of Common Stock                                        103       141
Proceeds from issuance of Common Stock of AMRC                                 --     1,500
Principal payments under capital leases                                      (135)     (952)
Proceeds from Bank Financing                                                2,000    35,000
Repayment of Bank Financing                                              (100,000)       --
Proceeds from bridge financing                                             10,000        --
Repayment of bridge financing                                             (10,000)       --
Proceeds from Senior Notes and Warrants                                   335,000        --
Payments on long-term debt                                                     --    (3,000)
Debt issuance costs                                                       (13,458)       (9)
                                                                          --------   -------
Net cash provided by financing activities                                 223,510    32,680


Net increase (decrease) in cash and cash equivalents                       19,173      (610)


CASH AND CASH EQUIVALENTS, beginning of period                              2,106     2,182
                                                                           ------    ------


CASH AND CASH EQUIVALENTS, end of period                                  $21,279    $1,572
                                                                          =======   =======


See notes to consolidated condensed financial statements.

</TABLE>


<PAGE>





                          PART I-FINANCIAL INFORMATION

                    Item 1. Financial Statements (continued)
             AMERICAN MOBILE SATELLITE CORPORATION AND SUBSIDIARIES
              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                                 March 31, 1998
                                   (Unaudited)


1. Organization and Business
- ----------------------------

American Mobile Satellite Corporation (with its subsidiaries,  "American Mobile"
or the  "Company")  was  incorporated  on May 3, 1988,  by eight of the  initial
applicants for the mobile satellite services license,  following a determination
by the Federal Communications  Commission ("FCC") that the public interest would
be best served by granting the license to a consortium of all willing, qualified
applicants.  The FCC has authorized  American Mobile to construct,  launch,  and
operate a mobile satellite services system (the "Satellite Network ") to provide
a full range of mobile voice and data  services via  satellite to land,  air and
sea-based  customers  in a service area  consisting  of the  continental  United
States,  Alaska,  Hawaii,  Puerto Rico, the U.S.  Virgin Islands,  U.S.  coastal
waters,  international  waters and airspace and any foreign  territory where the
local  government  has  authorized  the  provision  of  service.  In March 1991,
American Mobile Satellite Corporation  transferred the mobile satellite services
license ("MSS license") to a wholly owned subsidiary, American Mobile Subsidiary
Corporation  ("AMSC  Subsidiary").  On April 7, 1995,  the Company  successfully
launched its first satellite ("MSAT-2"), from Cape Canaveral, Florida.

On December  31,  1997,  the Company  (through  its  newly-formed,  wholly-owned
subsidiary, AMSC Acquisition Company, Inc. ("Acquisition Company"), entered into
a Stock  Purchase  Agreement  (the "Purchase  Agreement")  with  Motorola,  Inc.
("Motorola"),   for  the  acquisition  (the   "Acquisition")  of  ARDIS  Company
("ARDIS"),  a  wholly-owned  subsidiary  of  Motorola  that owns and  operates a
two-way wireless data communications  network. On March 3, 1998, the FCC granted
consent to consummate the  Acquisition,  and on March 31, 1998, the  Acquisition
and related  financing were completed.  The Company,  through the acquisition of
ARDIS,  becomes a  nationwide  provider  of  wireless  communications  services,
including data, dispatch, and voice services, primarily to business customers in
the United States.

On October 16, 1997,  American Mobile Radio Corporation,  an indirect subsidiary
of American  Mobile through its subsidiary  AMRC Holdings,  Inc.  (together with
American Mobile Radio Corporation,  "AMRC"), was awarded a license by the FCC to
provide  satellite-based  Digital Audio Radio Service  ("DARS")  throughout  the
United States, following its successful $89.9 million bid at auction on April 2,
1997.  AMRC has and will  continue to receive  funding for this business from an
independent  source  in  exchange  for  debt  and an  equity  interest  in AMRC.
Accordingly,  it is not expected that the development of this business will have
a material impact on the Company's financial position, results of operations, or
cash flows.

American Mobile is devoting its efforts to expanding a developing business. This
effort involves  substantial risk,  including  successfully  integrating  ARDIS.
Specifically,  future operating results will be subject to significant business,
economic,    regulatory,    technical,   and   competitive   uncertainties   and
contingencies. Depending on their extent and timing, these factors, individually
or in the  aggregate,  could have an adverse  effect on the Company's  financial
condition and future results of operations.




<PAGE>




2.  Significant Accounting Policies
- -----------------------------------

Basis of Presentation
- ---------------------

The unaudited  consolidated  condensed financial statements included herein have
been  prepared  pursuant  to the rules and  regulations  of the  Securities  and
Exchange  Commission.  Certain  information  and footnote  disclosures  normally
included in financial  statements prepared in accordance with generally accepted
accounting principles have been condensed or omitted. While the Company believes
that the  disclosures  made are adequate to make the information not misleading,
these consolidated  financial  statements should be read in conjunction with the
consolidated  financial  statements  and related notes included in the Company's
1997 Annual Report on Form 10-K.

The  consolidated  balance  sheet as of March  31,  1998,  and the  consolidated
statements  of loss and cash flows for the three months ended March 31, 1998 and
1997,  have been  prepared  by the  Company  without  audit.  In the  opinion of
management,   all  adjustments  (consisting  of  normal  recurring  adjustments)
necessary to present  fairly the financial  position,  result of operations  and
cash flows at March 31, 1998, and for all periods  presented have been made. The
balance  sheet at December  31,  1997 has been taken from the audited  financial
statements.

Acquisition
- -----------

Subject to certain  purchase price adjustment  provisions,  the Company acquired
ARDIS  for a  purchase  price  of $50  million  in cash and $50  million  in the
Company's Common Stock and warrants (the "Purchase Price").  Approximately $11.5
million  of the  shares  that are  issuable  to  Motorola  are  contingent  upon
stockholer  approval at the May 20, 1998 annual meeting of  stockholders.  These
have been included in the purchase  price shares since holders of  approximately
76% of the Company's  Common Stock have entered into an agreement  with Motorola
to approve  the  issuance  of the  additional  shares.  The  purchase  method of
accounting  for  business  combinations  was  used  for  the  recording  of  the
Acquisition.  The  operating  results  of ARDIS  have not been  included  in the
Company's  consolidated  statements of loss,  since the Acquisition  occurred on
March 31,  1998;  however,  the balance  sheet of ARDIS as of March 31, 1998 has
been included in the  consolidated  balance sheet of the Company.  The Company's
preliminary  estimate of the excess of the purchase price over the fair value of
net  assets  acquired  is  $67.6  million.  The  Company  has  not  specifically
identified amounts to assign to certain intangibles and licenses; changes in the
amounts  allocated  to such  assets  could  result in  changes  to the amount of
goodwill recorded.  A preliminary  amortization  period of twenty years has been
selected  for the pro forma  financial  information,  which is  expected  in all
material  respects to be  representative  of the amortization  expense that will
result from the ultimate allocation to the specific intangible assets.


The  unaudited pro forma  results give effect to (i) the  Acquisition,  (ii) the
Offering  and  (iii) the New Bank  Financing  as if such  transactions  had been
consummated on January 1 of each of the periods presented.

<TABLE>
<CAPTION>
                                                     Three Months Ended
                                                          March 31,
(dollars in thousands, except per share data)        1998          1997
                                                   --------      --------
<S>                                                <C>             <C>    
Revenues                                           $19,954         $19,513
Net loss                                          $(38,849)       $(41,257)
Loss per share                                      $(1.23)         $(1.32)
Weighted-average shares outstanding                 31,503          31,371
</TABLE>

Net Loss Per Share
- ------------------

Basic and diluted loss per common share is based on the weighted-average  number
of shares of Common  Stock  outstanding  during the  period.  Stock  options and
common stock  purchase  warrants are not  reflected  since their effect would be
antidilutive.

Recently Adopted Accounting Pronouncements
- ------------------------------------------

In June 1997, the Financial Accounting Standards Board ("FASB") issued Statement
of Financial  Accounting  Standards ("SFAS") No. 130,  "Reporting  Comprehensive
Income," and SFAS No. 131,  "Disclosures  about  Segments of an  Enterprise  and
Related  Information."  The Company  adopted SFAS No. 130 during the three month
period ended March 31, 1998.
<PAGE>



SFAS No.  130  requires  "comprehensive  income"  and the  components  of "other
comprehensive  income" to be reported in the financial  statements  and/or notes
thereto.  Since the Company does not have any components of "other comprehensive
income," reported net income is the same as "total comprehensive income" for the
three months ended March 31, 1997 and 1998.

SFAS  No.  131  requires  an  entity  to  disclose   financial  and  descriptive
information  about  its  reportable  operating  segments.  It  also  establishes
standards for related disclosures about products and services, geographic areas,
and  major  customers.  SFAS  No.  131 is not  required  for  interim  financial
reporting  purposes  during 1998. The Company is in the process of assessing the
additional disclosures, if any, required by SFAS No. 131. However, such adoption
will not impact the Company's results of operations or financial position, since
it relates only to disclosures.

Other
- -----

The Company paid  approximately $1.5 million and $1.1 million in the three-month
periods  ended March 31,  1998 and 1997,  respectively,  to related  parties for
capital assets,  service-related  obligations,  and payments under  pre-existing
agreements.  Payments  from  related  parties  for  communication  services  and
equipment  purchases totaled $1.1 million in the three-month  period ended March
31, 1998 and $471,000  million in the  three-month  period ended March 31, 1997.
Total  indebtedness  to related parties as of March 31, 1998  approximated  $3.1
million.

3.  Liquidity and Financing
- ---------------------------

$335 Million Unit Offering
- --------------------------

In  connection  with the  Acquisition,  discussed  above,  the Company,  through
Acquisition Company, issued $335 million of Units (the "Units") consisting of 12
1/4% Senior Notes due 2008 (the  "Notes"),  and  Warrants to purchase  shares of
Common Stock of the Company.  Each Unit consists of $1,000  principal  amount of
Notes and one Warrant to purchase  3.75749 shares of Common Stock at an exercise
price of $12.51 per share.  The  Warrants  were  valued at $8.5  million and are
reflected in the balance sheet as a debt discount. A portion of the net proceeds
of the sale of the Units were used to finance  the  Acquisition.  In  connection
with the Notes,  the  Company  has  purchased  approximately  $113.0  million of
pledged securities that are intended to provide for the payment of the first six
interest  payments on the Notes. The Company incurred  approximately $15 million
in costs  associated  with  the  placement  of the  Notes  and the  Acquisition.
Interest payments are due semi-annually, in arrears, beginning October 1, 1998.

New Bank Financing
- ------------------

In connection with the Acquisition, the Company, the Acquisition Company and its
subsidiaries  restructured  the existing $200 million Bank  Financing (the "Bank
Financing") to provide for two facilities:  (i) the Revolving Credit Facility, a
$100 million unsecured  five-year reducing  revolving credit facility,  and (ii)
the Term Loan Facility, a $100 million five-year,  term loan facility with up to
three  additional  one-year  extensions  subject to the lenders'  approval.  The
Revolving Credit Facility bears an interest rate, generally,  of 50 basis points
above  LIBOR and is  unsecured,  with a  negative  pledge  on the  assets of the
Acquisition Company and its subsidiaries  ranking pari passu with the Notes. The
Revolving  Credit  Facility will be reduced $10 million each quarter,  beginning
with the quarter ending June 30, 2002, with the balance due on maturity of March
31, 2003.  Borrowings under the Revolving Credit Facility are subject to certain
conditions  beginning in the fourth quarter of 1998. In the event the Company is
unable to borrow amounts under the Revolving Credit Facility, the Company's cash
needs will  significantly  exceed its  available  resources,  which would have a
material adverse effect on the Company. The Revolving Credit Facility ranks pari
passu with the  Notes.  The Term Loan  Facility  is secured by the assets of the
Company,  principally its stockholdings in AMRC and the Acquisition Company, and
will be effectively subordinated to the Revolving Credit Facility and the Notes.
The New Bank Financing is severally guaranteed by Hughes Electronics Corporation
("Hughes"),  Singapore  Telecommunications  Ltd. ("Singapore Telecom") and Baron
Capital  Partners,  L.P. (the "Bank Facility  Guarantors").  In exchange for the
additional risks  undertaken by the Bank Facility  Guarantors in connection with
the New Bank  Financing,  the Company  agreed to  compensate  the Bank  Facility
Guarantors,  principally  in the  form  of 1  million  additional  warrants  and
repricing of 5.5 million warrants  previously issued  (together,  the "Guarantee
Warrants").  The Guarantee  Warrants  have an exercise  price of $12.51 and have
been valued at  approximately  $17.7 million.  As of April 30, 1998, the Company
had  outstanding  borrowings of $100 million of the Term Loan Facility at 6.51%,
and $5.0 million under the Revolving Credit Facility at 6.1875%.


<PAGE>

In connection with the New Bank Financing,  the Company entered into an interest
rate swap  agreement.  The swap  agreement  reduces the impact of interest  rate
increases on the Term Loan  Facility.  The Company  paid a fee of  approximately
$17.9 million for the swap agreement. Under the swap agreement, the Company will
receive  an amount  equal to LIBOR  plus 50 basis  points,  paid on a  quarterly
basis, on a notional amount of $100 million until the termination  date of March
31,  2001.  The  Company  has  reflected  as an asset  the fee paid for the swap
agreement in the accompanying financial statements.  The Company is exposed to a
credit loss in the event of non  performance by the counter party under the swap
agreement.  The Company  does not  believe  there is a  significant  risk of non
performance  as the counter  party to the swap  agreement  is a major  financial
institution.

Motorola Vendor Financing
- -------------------------

Motorola has agreed to provide the Acquisition  Company with up to $10.0 million
of vendor financing (the "Vendor Financing Commitment"), which will be available
to finance up to 75% of the purchase price of additional  network base stations.
Loans under this  facility will bear interest at a rate equal to LIBOR plus 7.0%
and will be  guaranteed by the Company and each  subsidiary  of the  Acquisition
Company.  The terms of such  facility  will  require  that  amounts  borrowed be
secured by the  equipment  purchased  therewith.  This  commitment is subject to
customary  conditions,  including due  diligence,  and there can be no assurance
that the facility will be obtained by the Acquisition  Company on these terms or
at all. No amounts were outstanding under this facility as of April 30, 1998.

The Company  believes the proceeds  from the issuance of the Notes,  net of cash
used for the  Acquisition,  together  with  the  borrowings  under  the New Bank
Financing  and the  Vendor  Financing  Commitment,  will be  sufficient  to fund
operating losses, capital expenditures, working capital, and scheduled principal
and interest payments on debt through 1998 and beyond;  however, there can be no
assurance  that the Company's  current  projections  regarding the timing of its
ability to achieve positive  operating cash flow will be accurate,  and that the
Company will not need additional financing in the future.

AMRC
- ----

As previously  mentioned (see  "Organization and Business"),  AMRC was a winning
bidder for, and on October 16, 1997,  was awarded an FCC license to provide DARS
throughout the United States.  AMRC has and will continue to receive funding for
this  business  from an  independent  source in exchange  for debt and an equity
interest in AMRC.  Accordingly,  it is not expected that the development of this
business  will have a  material  impact  on the  Company's  financial  position,
results of operations, or cash flows. The Company's equity interest in AMRC may,
however, even on a fully diluted basis, become a material asset of the Company.

Summarized  financial  information  for AMRC as of March 31,  1998,  and for the
three months ended March 31, 1998 and 1997, and for the period from December 15,
1992 (date of inception) through March 31, 1998 is set forth below.
<TABLE>
<CAPTION>
                                                                                December 15, 1992
                                              Three Months                           through
dollars in thousands                         Ended March 31,                         March 31,
                                             ---------------                         ---------
                                            1998         1997                           1998
                                            ----         ----                           -----
<S>                                        <C>          <C>                          <C>  
Gross sales                                $  --        $  --                          $  --
Operating expenses                         1,367           --                          2,477
Loss from operations                       1,367           --                          2,477
Interest expense                              39           --                            588
Net loss                                   1,406           --                          3,065

</TABLE>

<TABLE>
<CAPTION>
                                                                        As of                  As of
                                                                      March 31,             December 31,
                                                                        1998                   1997
                                                                        -----                  ----
<S>                                                                   <C>                   <C>
Current assets                                                        $    --               $    --
Noncurrent assets                                                      99,194                91,933
Current liabilities                                                     4,696                82,949
Noncurrent liabilities                                                 86,921                    --
Total stockholders' equity                                              7,577                 8,983

</TABLE>
<PAGE>



Deferred Trade Payables
- -----------------------

In the last quarter of 1997 and the first quarter of 1998, the Company  arranged
the financing of certain trade payables, and as of March 31, 1998, $18.1 million
of deferred trade  payables were  outstanding at rates ranging from 6.23% to 14%
and are generally payable by the end of 1998.

Purchase and Lease Agreement
- ----------------------------

As  previously  disclosed,  the Company has entered into certain  agreements  to
acquire a one-half ownership interest in TMI Communications and Company, Limited
Partnership's ("TMI") satellite, MSAT-1, at a cost of $60 million payable over a
five-year  period,  as well as entered into a five-year  lease of the  Company's
satellite,  MSAT-2, with African Continental  Telecommunications  Ltd. ("ACTEL")
that provides for  aggregate  lease  payments to the Company of $182.5  million.
Closing under the  agreements is subject to a number of  conditions,  including:
United States and Canadian regulatory approvals, a successful financing by ACTEL
of at least $120 million, and completion of certain satellite testing, inversion
and relocation  activities  with respect to AMSC-1.  It is anticipated  that the
closing under both the purchase and lease  agreements will occur  simultaneously
in the third quarter of 1998.

4. Legal and Regulatory Matters
- -------------------------------

Like other mobile  service  providers in the  telecommunications  industry,  the
Company is subject to substantial domestic, foreign and international regulation
including the need for regulatory  approvals to operate and expand the Satellite
Network and operate and modify subscriber equipment.

The  owneship  and  operation  of  American  Mobile's  (MSS)  system  and ARDIS'
ground-based  two-way  wireless  data  system  are  subject  to  the  rules  and
regulations of the FCC, which acts under authority granted by the Communications
Act and related federal laws. Among other things,  the FCC allocates portions of
the radio  frequency  spectrum to certain  services  and grants  licenses to and
regulates  individual  entities using that spectrum.  American  Mobile and ARDIS
operates pursuant to various licenses granted by the FCC.

The  successful  operation of the Satellite  Network is dependent on a number of
factors,  including the amount of L-band  spectrum made available to the Company
pursuant  to  an  international  coordination  process.  The  United  States  is
currently  engaged in an  international  process of  coordinating  the Company's
access to the  spectrum  that the FCC has  assigned  to the  Company.  While the
Company  believes that  substantial  progress has been made in the  coordination
process and expects that the United  States  government  will be  successful  in
securing the necessary spectrum,  the process is not yet complete. The inability
of the United States  government  to secure  sufficient  spectrum  could have an
adverse effect on the Company's  financial  position,  results of operations and
cash flows.

The Company has the necessary regulatory  approvals,  some of which are pursuant
to  special  temporary  authority,  to  continue  its  operations  as  currently
contemplated.  The  Company has filed  applications  with the FCC and expects to
file applications in the future with respect to the continued operations, change
in  operation  and  expansion  of the Network and  certain  types of  subscriber
equipment.  Certain of its  applications  pertaining to future service have been
opposed.  While the Company, for various reasons,  believes that it will receive
the necessary  approvals on a timely basis,  there can be no assurance  that the
requests  will be granted,  will be granted on a timely basis or will be granted
on  conditions  favorable  to  the  Company.  Any  significant  changes  to  the
applications resulting from the FCC's review process or any significant delay in
their approval could adversely affect the Company's financial position,  results
of operations and cash flows.

American Mobile is authorized to build, launch and operate three  geosynchronous
satellites in accordance  with a specified  schedule.  American Mobile is not in
compliance with the schedule for commencement and construction of its second and
third satellites and has petitioned the FCC for changes to the schedule. Certain
of these extension requests have been opposed by third parties.  The FCC has not
acted on American  Mobile's  requests.  The FCC has the  authority to revoke the
authorizations  for the second and third satellites and, in connection with such
a revocation, could exercise its authority to rescind American Mobile's license.
American  Mobile  believes  that the  exercise of such  authority to rescind the
license is unlikely. The term of the license for each of American Mobile's three
authorized  satellites is ten years,  beginning when American  Mobile  certifies
that the respective  satellite is operating in compliance with American Mobile's
license.  The ten-year term of MSAT-2 began August 21, 1995.  Although  American
Mobile  anticipates  that the  authorizations  are likely to be  extended in due
course to correspond to the useful lives of the satellites and that new licenses
will be  granted  for  replacement  satellites,  there is no  assurance  of such
extension or grant.


<PAGE>



As a provider of interstate telecommunications services, the Company is required
to contribute to the FCC's universal  service fund, which supports the provision
of  telecommunication  services to  high-cost  areas,  and  establishes  funding
mechanisms  to support the provision of service to schools,  libraries and rural
health care providers.  The regulation became effective on January 1, 1998. This
cost  is not  born by the  Company,  but is  passed  on to its  customers  as is
universally practiced in the industry.

On June 5, 1996,  the FCC  waived  its  one-year  construction  requirement  and
granted ARDIS extensions of time to complete the buildouts of approximately  190
sites,  as required to maintain  previously  granted  licenses.  As of April 30,
1998,  ARDIS  intends but has yet to construct  94 of these sites.  The extended
construction  deadlines  vary by site  between June 27, 1998 and March 31, 1999.
Failure to complete the  buildouts in a timely  manner could result in a loss of
licenses  for such sites from the FCC.  In  addition,  at 11 of 104  uncompleted
sites  ARDIS is required to erect a new tower,  and there is no  assurance  that
local zoning  regulations  will not affect the timetable  for the  completion of
these  sites.  

In 1992, a former director of American Mobile filed an Amended Complaint against
the Company alleging  violations of the  Communications Act of 1934, as amended,
and of the Sherman Act and breach of  contract.  The suit seeks  damages for not
less than $100 million  trebled under the antitrust laws plus punitive  damages,
interest,  attorneys fees and costs. In mid-1992, the Company filed its response
denying all  allegations.  The Company's motion for summary  judgment,  filed on
March 31, 1994,  was denied on April 18, 1996. The trial in this matter has been
postponed  to a date to be  determined  in 1998.  Management  believes  that the
ultimate outcome of this matter will not be material to the Company's  financial
position, results of operations or cash flows.


5.  Other Matters
- -----------------

At March 31, 1998, the Company had remaining contractual commitments to purchase
both  mobile data  terminal  inventory  and mobile  telephone  inventory  in the
maximum amount of $6.4 million.



6.  AMSC Acquisition Company Financial Statements
- -------------------------------------------------

In connection with the Acquisition and related  financing  discussed  above, the
Company formed a new wholly-owned  subsidiary,  AMSC Acquisition  Company,  Inc.
("Acquisition  Company"). The Company transferred all of its inter-company notes
receivables  from  and its  rights,  title  and  interests  in  AMSC  Subsidiary
Corporation,  American Mobile Satellite Sales Corporation,  and AMSC Sales Corp.
Ltd. to Acquisition Company, and AMSC Acquisition Company, Inc. was the acquirer
of ARDIS and the issuer of the $335  million of Senior  Notes.  American  Mobile
Satellite  Corporation  ("Parent") has  guaranteed the Senior Notes.  The Senior
Notes  contain  covenants  that,  among  other  things,  limit  the  ability  of
Acquisition  Company to incur  additional  indebtedness,  pay  dividends or make
other distributions,  repurchase any capital stock or subordinated indebtedness,
make certain investments,  create certain liens, enter into certain transactions
with affiliates, sell assets, enter into certain mergers and consolidations, and
enter into sale and leaseback transactions.

Major  differences  between the financial  statements of Parent and  Acquisition
Company  include  (i)  as of the  Acquisition,  the  Term  Loan  Facility  is an
obligation of Parent and, as such,  the related debt and interest  costs are not
included in the Acquisition  Company  financial  statements for the period ended
and as of March 31, 1998, as discussed in Note 3, and (ii) certain  intercompany
management fees and expenses between the Parent and Acquisition Company that are
not eliminated at the Acquisition Company level.

The combined condensed financial statements of Acquisition Company are set forth
below.




<PAGE>



                         AMSC Acquisition Company, Inc.
                      Combined Condensed Statements of Loss
                             (dollars in thousands)
                                   (Unaudited)

<TABLE>
<CAPTION>

                                                    Three Months Ended
                                                         March 31,

                                                  1998              1997
                                                ---------         --------


REVENUES

<S>                                             <C>              <C>   
       Services                                   $6,418           $4,173
       Sales of equipment                          3,604            4,532
                                                  ------           ------

       Total Revenues                             10,022            8,705


COSTS AND EXPENSES:

       Cost of service and operations              7,728            8,873
       Cost of equipment sold                      3,881            5,442
       Sales and advertising                       2,993            3,221
       General and administrative                  3,659            4,777
       Depreciation and amortization              10,689           10,463
                                                  ------           ------

       Operating Loss                            (18,928)         (24,071)


INTEREST AND OTHER  INCOME                           141              945
INTEREST EXPENSE                                 (13,826)         (11,622)
                                                 --------         --------


NET LOSS                                        $(32,613)        $(34,748)
                                                =========        =========


</TABLE>













<PAGE>



                         AMSC Acquisition Company, Inc.
                        Combined Condensed Balance Sheets
                             (dollars in thousands)
                                   (Unaudited)

<TABLE>
<CAPTION>
                                                                                 March 31,    December 31,
ASSETS                                                                                1998            1997
                                                                                      ----            ----


CURRENT ASSETS:

<S>                                                                               <C>            <C>   
      Cash and cash equivalents                                                    $21,279          $2,106
      Inventory                                                                     38,554          40,321
      Accounts receivable-trade, net of allowance for doubtful accounts             11,477           8,140
      Restricted cash-current portion                                               41,038              --
      Prepaid in-orbit insurance                                                     2,889           4,564
      Other current assets                                                          15,324           9,608
                                                                                   -------         -------
             Total current assets                                                  130,561          64,739

PROPERTY AND EQUIPMENT - NET                                                       280,894         250,335
GOODWILL - NET                                                                      67,616              --
RESTRICTED CASH - Non-Current                                                       72,962              --
DEFERRED CHARGES AND OTHER ASSETS - NET                                             33,823          36,722
                                                                                   -------         -------

             Total assets                                                         $585,856        $351,796
                                                                                  ========        ========

LIABILITIES AND STOCKHOLDERS' EQUITY


CURRENT LIABILITIES:

      Accounts payable and accrued expenses                                        $27,990         $35,825
      Obligations under capital leases due within one year                           4,133             798
      Current portion of long-term debt                                             21,932          15,254
      Other current liabilities                                                      7,626           7,520
                                                                                  --------        --------
             Total current liabilities                                              61,681          59,397


DUE TO PARENT                                                                            --        441,836



LONG-TERM LIABILITIES:

      Obligations under Bank Financing                                                  --         198,000
      Senior Notes, net of discount                                                326,510              --
      Capital lease obligations                                                     12,005           3,147
      Other long-term debt                                                           1,126           1,364
      Net assets acquired in excess of purchase price (Note 12)                      2,550           2,725
      Other long-term liabilities                                                      610             647
                                                                                  --------        --------

             Total long-term liabilities                                           342,801         205,883

             Total liabilities                                                     404,482         707,116
                                                                                   -------         -------


STOCKHOLDERS' EQUITY:                                                              181,374       (355,320)
                                                                                   -------       ---------


             Total liabilities and stockholders' equity                           $585,856        $351,796
                                                                                  ========        ========


</TABLE>


<PAGE>



                         AMSC Acquisition Company, Inc.
                   Combined Condensed Statements of Cash Flows
                             (dollars in thousands)
                                   (Unaudited)

<TABLE>
<CAPTION>


                                                                     Three Months Ended
                                                                         March 31,
                                                              --------------------------------
                                                                    1998           1997
                                                                    ----           ----

CASH FLOWS USED IN OPERATING ACTIVITIES:
<S>                                                              <C>            <C>      
Net loss                                                         $(32,613)      $(35,598)
Adjustments to reconcile net loss to net cash used in
operating activities:
             Amortization of debt discount                          2,524          1,754
             Depreciation and amortization                         10,689         10,463
             Changes in assets and liabilities:
                 Inventory                                          1,986         (3,483)
                 Prepaid in-orbit insurance                         1,675          1,693
                 Trade accounts receivable                          3,744         (1,480)
                 Other current assets                                (661)         1,051
                 Accounts payable and accrued expenses            (12,182)        (9,065)
                 Deferred trade payables                            6,436             --
                 Deferred items - net                                 293             --
                                                                   -------        ------

Net cash used in operating activities                             (18,109)       (34,665)


CASH FLOWS USED IN INVESTING ACTIVITIES:

Additions to property and equipment                                (1,126)        (3,574)
Acquisition of ARDIS                                              (51,382)            --
Purchase of restricted cash securities                           (113,050)            --
                                                                 ---------        ------
Net cash used in investing activities                            (165,508)        (3,574)

CASH FLOWS FROM FINANCING ACTIVITIES:

Funding from Parent                                               (12,127)         6,590
Principal payments under capital leases                              (135)          (952)
Proceeds from Bank Financing                                        2,000         35,000
Repayment of Bank Financing                                      (100,000)            --
Proceeds from bridge financing                                     10,000             --
Repayment of bridge financing                                     (10,000)            --
Proceeds from Senior Notes                                        326,510             --
Payments on long-term debt                                             --         (3,000)
Debt issuance costs                                               (13,458)            (9)
                                                                  --------        -------

Net cash provided by  financing activities                        202,790         37,629

Net increase (decrease) in cash and cash equivalents               19,173           (610)

CASH AND CASH EQUIVALENTS, beginning of period                      2,106          2,182
                                                                 --------         -------
CASH AND CASH EQUIVALENTS, end of period                          $21,279         $1,572
                                                                 ========         =======
</TABLE>






<PAGE>



                           PART I-FINANCIAL STATEMENTS

                 Item 2. Management's Discussion and Analysis of
              Interim Financial Condition and Results of Operations

This Quarterly Report on Form 10-Q includes "forward-looking  statements" within
the meaning of Section 27A of the  Securities Act of 1933 and Section 21E of the
Securities  Exchange Act of 1934.  Such  statements are identified by the use of
forward-looking  words or phrases  including,  but not limited  to,  "believes,"
"intended,"   "will  be   positioned,"   "expects,"   "expected,"   "estimates,"
"anticipates" and "anticipated." These  forward-looking  statements are based on
the Company's  current  expectations.  All statements  other than  statements of
historical  facts included in this Annual Report,  including those regarding the
Company's financial position,  business strategy,  projected costs and financing
needs,  and plans and  objectives  of  management  for  future  operations,  are
forward-looking statements.  Although the Company believes that the expectations
reflected in such  forward-looking  statements are  reasonable,  there can be no
assurance  that  such  expectations  will  prove to have been  correct.  Because
forward-looking statements involve risks and uncertainties, the Company's actual
results  could  differ  materially.  Important  factors  that could cause actual
results  to  differ  materially  from the  Company's  expectations  ("Cautionary
Statements")  are disclosed under  "Business" and  "Management's  Discussion and
Analysis of Financial  Condition  and Results of  Operations,"  and elsewhere in
this Annual Report,  including,  without  limitation,  in  conjunction  with the
forward-looking statements included in this Annual Report. These forward-looking
statements  represent the  Company's  judgment as of the date hereof and readers
are cautioned not to place undue reliance on these  forward-looking  statements.
All subsequent written and oral forward-looking  statements  attributable to the
Company or persons  acting on behalf of the Company are  expressly  qualified in
their entirety by the Cautionary Statements. Readers should carefully review the
risk factors  described in other  documents  the Company files from time to time
with the  Securities  and Exchange  Commission,  including  the Form 10-K Annual
Report filed on March 31, 1998,  the Form 10-K/A  Amended Annual Report filed on
April 15, 1998, the Current Report on Form 8-K filed on April 15, 1998, and Form
10-Q Quarterly  Reports to be filed by the Company  subsequent to this Form 10-Q
Quarterly Report and any Current Reports on Form 8-K and registration statements
filed by the Company.


General
- -------

The following  discussion and analysis  provides  information  which  management
believes  is  relevant  to an  assessment  and  understanding  of the  financial
condition and  consolidated  results of operations of American Mobile  Satellite
Corporation  (with its subsidiaries,  "American  Mobile" or the "Company").  The
discussion  should  be read  in  conjunction  with  the  consolidated  financial
statements and notes thereto.

American Mobile  Satellite  Corporation was  incorporated in May 1988 and, until
1996,  was a  development  stage  company,  engaged  primarily  in  the  design,
development,  construction,  deployment  and  financing  of a  mobile  satellite
communication   system.   On  December  31,  1997,  the  Company   (through  its
newly-formed subsidiary AMSC Acquisition Company, Inc. ("Acquisition Company")),
entered  into  a  Stock  Purchase  Agreement  (the  "Purchase  Agreement")  with
Motorola,  Inc.  ("Motorola"),  for the acquisition (the "Acquisition") of ARDIS
Company ("ARDIS"), a wholly-owned  subsidiary of Motorola that owns and operates
a two-way  wireless  data  communications  network.  On March 3,  1998,  the FCC
granted  consent  to  consummate  the  Acquisition.   On  March  31,  1998,  the
Acquisition  and related  financing were  completed.  See "Liquidity and Capital
Resources."  With the  acquisition  of  ARDIS,  the  Company  becomes  a leading
provider  of  nationwide  wireless  communications  services,   including  data,
dispatch  and voice  services,  primarily  to business  customers  in the United
States.  The  Company  offers a broad  range of  end-to-end  wireless  solutions
utilizing  a  seamless  network   consisting  of  the  nation's  largest,   most
fully-deployed  terrestrial  wireless  data network (the "ARDIS  Network") and a
satellite  in  geosynchronous  orbit (the  "Satellite  Network") (together,  the
"Network").

In connection with the  Acquisition,  the Company and its  subsidiaries  entered
into agreements with respect to the following  financings and refinancings:  (1)
$335  million of Units;  (2) the  restructuring  of its  existing  $200  million
Revolving  Credit Facility and Term Loan Facility  (collectively,  the "New Bank
Financings");  and (3) $10 million  commitment  with respect to Motorola  vendor
financing.  See "Management's Discussion and Analysis of Financial Condition and
Results of  Operations  - Liquidity  and Capital  Resources."  Additionally,  in
connection with the Acquisition and related financing,  the Company  transferred
all of its rights, title and interests in AMSC Subsidiary Corporation,  American
Mobile  Satellite  Sales  Corporation,  and AMSC  Sales  Corp.  Ltd.  (together,
"American Mobile Subsidiaries") to Acquisition Company.


<PAGE>



On October 16, 1997,  American Mobile Radio Corporation,  an indirect subsidiary
of American  Mobile through its subsidiary  AMRC Holdings,  Inc.  (together with
American Mobile Radio Corporation,  "AMRC"), was awarded a license by the FCC to
provide  satellite-based  Digital Audio Radio Service  ("DARS")  throughout  the
United States, following its successful $89.9 million bid at auction on April 2,
1997. The  operations  and financing of AMRC are  maintained  separate and apart
from the  operations  and  financing  of  American  Mobile (see  "Liquidity  and
Financing").

Management  believes the period to period comparison of the Company's  financial
results  are not  necessarily  meaningful  and should  not be relied  upon as an
indication of future  operating  performance  due to the Company's  historically
high growth rate and the acquisition of ARDIS.


Overview
- --------

Each of American Mobile and ARDIS has incurred significant  operating losses and
negative cash flows in each year since it commenced operations, due primarily to
start-up  costs,  the costs of developing and building each network and the cost
of developing,  selling and providing its respective products and services.  The
Company is, and will continue to be, highly leveraged. As of March 31, 1998, the
Company had indebtedness of approximately $465.7 million.

The Company's future operating  results could be adversely  affected by a number
of uncertainties and factors, including (i) the timely completion and deployment
of  future  products  and  related  services,   including  among  other  things,
availability of mobile telephones, data terminals and other equipment to be used
with the Network  ("Subscriber  Equipment") being  manufactured by third parties
over which the Company has limited control,  (ii) the market's acceptance of the
Company's  services,  (iii) the  ability  and the  commitment  of the  Company's
distribution channels to market and distribute the Company's services,  (iv) the
Company's  ability to modify  its  organization,  strategy  and  product  mix to
maximize the market  opportunities in light of changes therein,  (v) competition
from existing  companies that provide  services  using  existing  communications
technologies  and the  possibility  of  competition  from  companies  using  new
technology  in  the  future,   (vi)  capacity   constraints   arising  from  the
reconfiguration of MSAT-2,  subsequent anomalies affecting MSAT-2 and MSAT-1, or
the power management  recommendation affecting both MSAT-2 and MSAT-1 previously
reported,  (vii)  additional  technical  anomalies  that may  occur  within  the
Satellite   Network, including those relating to MSAT-1 and MSAT-2,  which could
impact, among other things, the operation of the Satellite Network and the cost,
scope  or  availability  of  in-orbit  insurance,  (viii)  subscriber  equipment
inventory  responsibilities and liabilities assumed by the Company including the
ability of the Company to realize the value of its inventory in a timely manner,
(ix) the Company's ability to secure  additional  financing as may be necessary,
(x) the  Company's  ability to respond and react to changes in its  business and
the  industry  as a result of being  highly  leveraged,  (xi) the ability of the
Company  to  successfully  integrate  ARDIS  and  to  achieve  certain  business
synergies, and (xii) the ability of the Company to manage growth effectively.

As of March 31, 1998, there were approximately 85,200 units on the Network.


Quarter Ended March 31, 1998 and 1997
- -------------------------------------

Service  revenues,  which  include both the Company's  voice and data  services,
approximated  $6.4  million for the quarter  ended March 31, 1998 as compared to
$4.2 million for the same period in 1997 and represents a 52% increase year over
year.  Service revenue from voice services increased 78% from approximately $1.8
million  in the first  quarter  of 1997 to  approximately  $3.2  million  in the
comparable  period of 1998. The $1.4 million  increase was primarily a result of
an 85% increase in voice customers  during the first quarter of 1998 as compared
to the  comparable  period in 1997.  Service  revenue  from the  Company's  data
services  approximated $2.3 million in the first quarter of 1998, as compared to
$1.6 million for the comparable quarter of 1997, an increase of $700,000 or 44%.
The  increase was  primarily a result of a 25%  increase in data units.  Service
revenue  from  capacity  resellers,  who handle  both  voice and data  services,
approximated  $805,000 in the first quarter of 1998, as compared to $518,000 for
the first  quarter of 1997, an increase of $287,000 or 55%. As of March 31, 1998
and 1997,  receivables  relating to service  revenues were $4.0 million and $3.0
million, respectively.

Revenue from the sale of mobile data terminals and mobile  telephones  decreased
20% from $4.5 million in the first  quarter of 1997 to $3.6 million in the first
quarter of 1998.  The decrease was  primarily  attributable  to reduced sales of



<PAGE>



voice products, as well as certain price reductions made in the first quarter of
1998. As of March 31, 1998 and 1997,  receivables  relating to equipment revenue
were $2.5 million and $7.0 million respectively.

Cost of service and  operations  for the first quarter of 1998,  which  includes
costs to support  subscribers  and to operate the Satellite  Network,  were $7.7
million for 1998 and $8.9  million for the same period of 1997.  Cost of service
and  operations  for the first  quarter  of 1998 and 1997,  as a  percentage  of
revenues, were 77% and 102%,  respectively.  The decrease in cost of service and
operations was primarily  attributable to a reduction in information  technology
costs affected by dramatically  reducing the dependence on outside  consultants,
offset by increased  interconnect  charges  associated  with  increased  service
usage.

The cost of equipment  sold decreased 28% from $5.4 million in the first quarter
of 1997 to $3.9 million for the same period in 1998. The dollar  decrease in the
cost of equipment sold is primarily attributable to (i) a corresponding decrease
in voice  equipment  sales  and  (ii)  the  impact  of the  inventory  valuation
allowance recorded in the fourth quarter of 1997.

Sales and  advertising  expenses were $3.0 million in the first quarter of 1998,
compared  to $3.2  million for the same  period in 1997.  Sales and  advertising
expenses as a percentage  of revenue  were 30% in the first  quarter of 1998 and
37% in the first quarter of 1997. The decrease of sales and advertising expenses
was primarily attributable to a reduction in subscriber acquisition costs as the
first quarter marketing and promotional initiatives were put on hold pending the
Acquisition.  It is  anticipated  that these costs will  increase as the Company
rolls out new marketing programs associated with the new corporate strategy.

General  and  administrative  expenses  for the first  quarter of 1998 were $3.6
million,  compared to $4.9 million in the first quarter of 1997. As a percentage
of revenue,  general and  administrative  expenses  represented 36% in the first
quarter of 1998 and 56% in the first  quarter of 1997.  The  decrease in general
and administrative expenses for 1998 compared to 1997 was primarily attributable
to (i) a $775,000 reduction in personnel expenses as a result of deferred hiring
decisions and (ii) a $371,000 reduction in insurance premiums, primarily related
to the negotiation of better rates on certain key insurance policies.

Depreciation and amortization expense was $10.2 million and $9.9 million for the
first quarter of 1998 and 1997,  respectively,  representing  approximately 101%
and 114% of revenue for the first quarter of 1998 and 1997, respectively.
 The increase in  depreciation  and  amortization  expense was  attributable  to
depreciation on newly-acquired assets.

Interest and other income was $141,000 for the first quarter of 1998 compared to
$945,000 for the same period in 1997.  The decrease was a result of other income
in the amount of $875,000  representing  proceeds  from the licensing of certain
technology  associated with the Satellite  Network received in the first quarter
of 1997,  offset by a $100,000  increase  in interest  income  earned on certain
escrowed  monies.  The Company  incurred $6.6 million of interest expense in the
first  quarter of 1998  compared  to $4.4  million  for the same period in 1997,
reflecting (i) the  amortization of debt discount and debt offering costs in the
amount of $2.5  million in 1998,  compared  to $1.8  million  in 1997,  and (ii)
higher outstanding loan balances as compared to 1997.

Interest  expense in the first  quarter of 1998 was  significant  as a result of
borrowings  under the Bank Financing,  as well as the  amortization of borrowing
costs incurred in conjunction with securing the facility. It is anticipated that
interest  costs  will  continue  to be  significant  as a  result  of  the  Bank
Financing,  Bridge  Financing,  and  Acquisition,  (see  "Liquidity  and Capital
Resources").

Net capital expenditures,  including additions financed through vendor financing
arrangements,  for the first quarter of 1998 for property and  equipment  were $
1.1 million  compared to $1.8 million for the same period in 1997.  The decrease
was largely attributable to the reduction in the acquisition of assets necessary
to complete the satellite network.


Liquidity and Capital Resources
- -------------------------------

$335 Million Unit Offering
- --------------------------

In  connection  with the  Acquisition,  discussed  above,  the Company,  through
Acquisition Company, issued $335 million of Units (the "Units") consisting of 12
1/4% Senior Notes due 2008 (the  "Notes"),  and  Warrants to purchase  shares of


<PAGE>



Common Stock of the Company.  Each Unit consists of $1,000  principal  amount of
Notes and one Warrant to purchase  3.75749 shares of Common Stock at an exercise
price of $12.51 per share.  The  Warrants  were  valued at $8.5  million and are
reflected in the balance sheet as a debt discount. A portion of the net proceeds
of the sale of the Units were used to finance  the  Acquisition.  In  connection
with the Notes,  the  Company  has  purchased  approximately  $113.0  million of
pledged securities that are intended to provide for the payment of the first six
interest  payments on the Notes. The Company incurred  approximately $15 million
in costs  associated  with  the  placement  of the  Notes  and the  Acquisition.
Interest payments are due semi-annually, in arrears, beginning October 1, 1998.

New Bank Financing
- ------------------

In connection with the Acquisition, the Company, the Acquisition Company and its
subsidiaries  restructured  the existing $200 million Bank  Financing (the "Bank
Financing") to provide for two facilities:  (i) the Revolving Credit Facility, a
$100 million unsecured  five-year reducing  revolving credit facility,  and (ii)
the Term Loan Facility, a $100 million five-year,  term loan facility with up to
three  additional  one-year  extensions  subject to the lenders'  approval.  The
Revolving Credit Facility bears an interest rate, generally,  of 50 basis points
above  LIBOR and is  unsecured,  with a  negative  pledge  on the  assets of the
Acquisition Company and its subsidiaries  ranking pari passu with the Notes. The
Revolving  Credit  Facility will be reduced $10 million each quarter,  beginning
with the quarter ending June 30, 2002, with the balance due on maturity of March
31, 2003.  Borrowings under the Revolving Credit Facility are subject to certain
conditions  beginning in the fourth quarter of 1998. In the event the Company is
unable to borrow amounts under the Revolving Credit Facility, the Company's cash
needs will  significantly  exceed its  available  resources,  which would have a
material adverse effect on the Company. The Revolving Credit Facility ranks pari
passu with the  Notes.  The Term Loan  Facility  is secured by the assets of the
Company,  principally its stockholdings in AMRC and the Acquisition Company, and
will be effectively subordinated to the Revolving Credit Facility and the Notes.
The New Bank Financing is severally guaranteed by Hughes Electronics Corporation
("Hughes"),  Singapore  Telecommunications  Ltd. ("Singapore Telecom") and Baron
Capital  Partners,  L.P. (the "Bank Facility  Guarantors").  In exchange for the
additional risks  undertaken by the Bank Facility  Guarantors in connection with
the New Bank  Financing,  the Company  agreed to  compensate  the Bank  Facility
Guarantors,  principally  in the  form  of 1  million  additional  warrants  and
repricing of 5.5 million warrants  previously issued  (together,  the "Guarantor
Warrants").  The Guarantee  Warrants  have an exercise  price of $12.51 and have
been valued at  approximately  $17.7 million.  As of April 30, 1998, the Company
had  outstanding  borrowings of $100 million of the Term Loan Facility at 6.51%,
and $5.0 million under the Revolving Credit Facility at 6.1875%.

In connection with the New Bank Financing,  the Company entered into an interest
rate swap  agreement.  The swap  agreement  reduces the impact of interest  rate
increases on the Term Loan  Facility.  The Company  paid a fee of  approximately
$17.9 million for the swap agreement. Under the swap agreement, the Company will
receive  an amount  equal to LIBOR  plus 50 basis  points,  paid on a  quarterly
basis, on a notional amount of $100 million until the termination  date of March
31,  2001.  The  Company  has  reflected  as an asset  the fee paid for the swap
agreement in the accompanying financial statements.  The Company is exposed to a
credit loss in the event of non  performance by the counter party under the swap
agreement.  The Company  does not  believe  there is a  significant  risk of non
performance  as the counter  party to the swap  agreement  is a major  financial
institution.

Motorola Vendor Financing
- -------------------------

Motorola has agreed to provide the Acquisition  Company with up to $10.0 million
of vendor financing (the "Vendor Financing Commitment"), which will be available
to finance up to 75% of the purchase price of additional  network base stations.
Loans under this  facility will bear interest at a rate equal to LIBOR plus 7.0%
and will be  guaranteed by the Company and each  subsidiary  of the  Acquisition
Company.  The terms of such  facility  will  require  that  amounts  borrowed be
secured by the  equipment  purchased  therewith.  This  commitment is subject to
customary  conditions,  including due  diligence,  and there can be no assurance
that the facility will be obtained by the Acquisition  Company on these terms or
at all. No amounts were outstanding under this facility as of April 30, 1998.

The Company  believes the proceeds  from the issuance of the Notes,  net of cash
used for the  Acquisition,  together  with  the  borrowings  under  the New Bank
Financing  and the  Vendor  Financing  Commitment,  will be  sufficient  to fund
operating losses, capital expenditures, working capital, and scheduled principal
and interest payments on debt through 1998 and beyond;  however, there can be no
assurance  that the Company's  current  projections  regarding the timing of its
ability to achieve positive  operating cash flow will be accurate,  and that the
Company will not need additional financing in the future.


<PAGE>

AMRC
- ----

As previously  mentioned (see  "Organization and Business"),  AMRC was a winning
bidder for, and on October 16, 1997,  was awarded an FCC license to provide DARS
throughout the United States.  AMRC has and will continue to receive funding for
this  business  from an  independent  source in exchange  for debt and an equity
interest in AMRC.  Accordingly,  it is not expected that the development of this
business  will have a  material  impact  on the  Company's  financial  position,
results of operations, or cash flows. The Company's equity interest in AMRC may,
however, even on a fully diluted basis, become a material asset of the Company.

Deferred Trade Payables
- -----------------------

In the last quarter of 1997 and the first quarter of 1998, the Company  arranged
the financing of certain trade payables, and as of March 31, 1998, $18.1 million
of deferred trade  payables were  outstanding at rates ranging from 6.23% to 14%
and are generally payable by the end of 1998.

Purchase and Lease of Satellite
- -------------------------------

As  previously  disclosed,  the Company has entered into certain  agreements  to
acquire a one-half ownership interest in TMI Communications and Company, Limited
Partnership's ("TMI") satellite, MSAT-1, at a cost of $60 million payable over a
five-year  period,  as well as entered  into  five-year  lease of the  Company's
satellite,  MSAT-2,  with  African  Continental   Telecommunications  Ltd.  that
provides for aggregate lease payments to the Company of $182.5 million.  Closing
under the  agreements is subject to a number of  conditions,  including:  United
States and Canadian regulatory approvals,  a successful financing by ACTEL of at
least $120 million,  and completion of certain satellite testing,  inversion and
relocation activities with respect to AMSC-1. It is anticipated that the closing
under  both the  purchase  and lease  agreements  will occur  simultaneously  in
the third quarter of 1998.

Other
- -----

At March 31, 1998, the Company had remaining contractual commitments to purchase
both mobile data terminal inventory and mobile telephone inventory approximating
$6.4 million.

Cash  used in  operating  activities  for the  first  quarter  of 1998 was $10.9
million as compared to $26.7 million for the first quarter of 1997. The decrease
in cash used in operating activities was primarily attributable to (i) decreased
operating losses, and (ii) decreased inventory and accounts receivable balances.
Cash used by investing  activities  was $193.4  million for the first quarter of
1998 compared to $6.6 million during the first quarter of 1997. The increase was
primarily  attributable  to the  acquisition of ARDIS and the funding of certain
escrows required in connection with the Acquisition.  Cash provided by financing
activities  was $223.5  million  during the first quarter of 1998 as compared to
$32.7 million during the first quarter of 1997, reflecting (i) the proceeds from
the Notes Bank,  offset by (ii) the repayment of a portion of the Bank Financing
and (iii)  payment of financing  fees  associated  with the  acquisition  of the
Notes.  As of March 31,  1998,  the Company  had $21.3  million of cash and cash
equivalents and working capital of $71.4 million.

Other Matters
- -------------

In June 1997, the Financial Accounting Standards Board ("FASB") issued Statement
of Financial  Accounting  Standards ("SFAS") No. 130,  "Reporting  Comprehensive
Income," and SFAS No. 131,  "Disclosures  about  Segments of an  Enterprise  and
Related  Information."  The Company  adopted SFAS No. 130  standards  during the
three month period ended March 31, 1998.

SFAS No.  130  requires  "comprehensive  income"  and the  components  of "other
comprehensive  income" to be reported in the financial  statements  and/or notes
thereto.  Since the Company does not have any components of "other comprehensive
income," reported net income is the same as "total comprehensive income" for the
three months ended March 31, 1997 and 1998.

SFAS  No.  131  requires  an  entity  to  disclose   financial  and  descriptive
information  about  its  reportable  operating  segments.  It  also  establishes
standards for related disclosures about products and services, geographic areas,
and  major  customers.  SFAS  No.  131 is not  required  for  interim  financial
reporting  purposes  during 1998. The Company is in the process of assessing the
additional disclosures, if any, required by SFAS No. 131. However, such adoption
will not impact the Company's results of operations or financial position, since
it relates only to disclosures.




<PAGE>



                          PART II -- OTHER INFORMATION

                    Item 6. Exhibits and Reports on Form 8-K

               (a) Exhibits

3.1       -    Restated  Certificate  of  Incorporation  of  AMSC  (as  restated
               effective May 1, 1996)  (Incorporated by reference to Exhibit 3.1
               to the  Company's  Quarterly  Report on Form 10-Q for the periods
               ending March 31,1996 and June 30, 1996 (File No. 0-23044))

3.2       -    Amended and  Restated  Bylaws of AMSC (as  amended  and  restated
               effective  February  29,  1996)  (Incorporated  by  reference  to
               Exhibit 3.2 to the  Company's  Annual Report on Form 10-K for the
               fiscal year ending December 31, 1995 (File No. 0-23044))

4.1       -    Indenture of AMSC Acquisition Company,  Inc., Series A and Series
               B,  12  1/4%  Senior  Notes  Due  2008,   dated  March  31,  1998
               (Incorporated by reference to Registration  Statement on Form S-4
               filed on even date herewith.)

4.2       -    Debt  Registration  Rights  Agreement dated March 31, 1998 by and
               among AMSC Acquisition  Company,  Inc., Bear, Stearns & Co. Inc.,
               J.P.  Morgan  Securities  Inc.,  TD  Securities  (USA)  Inc.  and
               BancAmerica  Robertson  Stephens,  and  guarantors  party thereto
               (Incorporated by reference to Registration  Statement on Form S-4
               filed on even date herewith.)

4.3       -    Unit Agreement Among American  Mobile Satellite Corporation, AMSC
               Acquisition Company, Inc. and State Street Bank and Trust Company
               as Unit Agent, dated March 31, 1998 (Incorporated by reference to
               Registration Statement on Form S-4 filed on even date herewith.)

4.4       -    Warrant Agreement  between American Mobile Satellite  Corporation
               as Issuer  and State  Street  Bank and Trust  Company  as Warrant
               Agent  dated  March  31,  1998   (Incorporated  by  reference  to
               Registration Statement on Form S-4 filed on even date herewith.)

4.5       -    Warrant Registration Rights Agreement dated March 31, 1998 By and
               Among American Mobile Satellite  Corporation and Bear,  Stearns &
               Co. Inc., J.P. Morgan  Securities  Inc.,  T.D.  Securities  (USA)
               Inc.,  BancAmerica Robertson Stephens  (Incorporated by reference
               to  Registration  Statement  on  Form  S-4  filed  on  even  date
               herewith.)

4.6       -    Pledge  and  Security  Agreement  by and among  AMSC  Acquisition
               Company,  Inc.,  State Street Bank and Trust Company,  as Trustee
               and State  Street Bank and Trust  Company,  as  Collateral  Agent
               dated March 31, 1998  (Incorporated  by reference to Registration
               Statement on Form S-4 filed on even date herewith.)

10.65     -    Stock  Purchase  Agreement for the  Acquisition of Motorola ARDIS
               Acquisition,  Inc. and Motorola ARDIS,  Inc. by AMSC  Acquisition
               Company,  Inc., a Wholly-  Owned  Subsidiary  of American  Mobile
               Satellite   Corporation,   Dated   as  of   December   31,   1997
               (Incorporated by reference to Exhibit 10.65 previously filed with
               the Report on Form 10-K for the period  ending  December 31, 1997
               (File No. 0-23044)).

10.65(a)  -    Amendment  No.  1dated  March  31,  1998  to the  Stock  Purchase
               Agreement for the Acquisition of Motorola ARDIS Acquisition, Inc.
               and Motorola ARDIS,  Inc. by AMSC  Acquisition  Company,  Inc., a
               Wholly-Owned  Subsidiary of American Mobile Satellite Corporation
               (Incorporated  by  reference  to Exhibit 4.2 to the  Schedule 13D
               dated March 31, 1998, filed by Motorola, Inc.)


<PAGE>

10.66     -    Participation  Rights  Agreement  by and  among  Motorola,  Inc.,
               American Mobile Satellite Corporation,  and the parties listed on
               Schedule  A,  dated as of  December  31,  1997  (Incorporated  by
               reference to Exhibit  10.66  previously  filed with the Report on
               Form 10-K for the  period  ending  December  31,  1997  (File No.
               0-23044)).

10.67     -    Registration  Rights  Agreement  by  and  among  Motorola,  Inc.,
               American Mobile Satellite  Corporation dated as of March 31, 1998
               (Incorporated  by  reference  to Exhibit 4.4 to the  Schedule 13D
               dated March 31, 1998, filed by Motorola, Inc.)

10.68     -    Guaranty  Issuance  Agreement,  dated as of March 31, 1998, among
               Hughes  Electronics  Corporation,   Singapore  Telecommunications
               Ltd.,  and Baron  Capital  Partners,  L.P.  and  American  Mobile
               Satellite   Corporation  and  AMSC  Acquisition   Company,   Inc.
               (Incorporated by reference to Exhibit 1 to the Schedule 13D dated
               March  31,  1998,  filed  by  Hughes   Communications   Satellite
               Services, Inc. )

10.69     -    Warrant for the  Purchase  of Shares of Common  Stock of American
               Mobile  Satellite  Corporation,   dated  as  of  March  31,  1998
               (Incorporated by reference to Exhibit 2 to the Schedule 13D dated
               March  31,  1998,  filed  by  Hughes   Communications   Satellite
               Services, Inc. )

10.70     -    Amended and Restated  Registration Rights Agreement,  dated as of
               March 31, 1998, among American Mobile  Satellite  Corporation and
               Hughes  Electronics  Corporation,   Singapore  Telecommunications
               Ltd., and Baron Capital Partners, L.P. (Incorporated by reference
               to Exhibit 3 to the Schedule  13D dated March 31, 1998,  filed by
               Hughes Communications Satellite Services, Inc.)

10.71     -    Amendment No. 2 to the Warrant Certificate, dated as of March 31,
               1998, by and among  American  Mobile  Satellite  Corporation  and
               Hughes  Electronics  Corporation,   Singapore  Telecommunications
               Ltd., and Baron Capital Partners, L.P. (Incorporated by reference
               to Exhibit 4 to the Schedule  13D dated March 31, 1998,  filed by
               Hughes Communications Satellite Services, Inc. )

10.72     -    Term Credit  Agreement  dated as of March 31, 1998 among American
               Mobile  Satellite  Corporation,  Morgan Guaranty Trust Company of
               New York,  Toronto Dominion  (Texas),  Inc. and other banks party
               thereto (filed herewith.)

10.73     -    Revolving  Credit Agreement dated as of March 31, 1998 among AMSC
               Acquisition Company, Inc., American Mobile Satellite Corporation,
               Morgan  Guaranty  Trust Company of New York and Toronto  Dominion
               (Texas), Inc. and other banks party thereto (filed herewith.)

11.1      -    Computations of Earning Per Common Share (filed herewith)

27.0      -    Financial Data Schedule (filed herewith)


               (b) Reports on Form 8-K:

         On April 15,  1998,  the  Company  filed a Current  Report on Form 8-K,
         describing in response to Item  2-Acquisition or Disposition of Assets,
         the acquisition of ARDIS Company from Motorola, Inc.




<PAGE>



                                    SIGNATURE

Pursuant  to the  requirements  of the  Securities  Exchange  Act of  1934,  the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned thereunto duly authorized.

                                    AMERICAN MOBILE SATELLITE CORPORATION
                                    (Registrant)


Date: May 14, 1998                  By:/s/STEPHEN D. PECK
                                    --------------------------------------------
                                    Stephen D. Peck
                                    Vice President and Chief Financial Officer
                                    (principal financial and accounting officer)



<PAGE>



                                  EXHIBIT INDEX



Number            Description

3.1       -    Restated  Certificate  of  Incorporation  of  AMSC  (as  restated
               effective May 1, 1996)  (Incorporated by reference to Exhibit 3.1
               to the  Company's  Quarterly  Report on Form 10-Q for the periods
               ending March 31,1996 and June 30, 1996 (File No. 0-23044))

3.2       -    Amended and  Restated  Bylaws of AMSC (as  amended  and  restated
               effective  February  29,  1996)  (Incorporated  by  reference  to
               Exhibit 3.2 to the  Company's  Annual Report on Form 10-K for the
               fiscal year ending December 31, 1995 (File No. 0-23044))

4.1       -    Indenture of AMSC Acquisition Company,  Inc., Series A and Series
               B,  12  1/4%  Senior  Notes  Due  2008,   dated  March  31,  1998
               (Incorporated by reference to Registration  Statement on Form S-4
               filed on even date herewith.)

4.2       -    Debt  Registration  Rights  Agreement dated March 31, 1998 by and
               among AMSC Acquisition  Company,  Inc., Bear, Stearns & Co. Inc.,
               J.P.  Morgan  Securities  Inc.,  TD  Securities  (USA)  Inc.  and
               BancAmerica  Robertson  Stephens,  and  guarantors  party thereto
               (Incorporated by reference to Registration  Statement on Form S-4
               filed on even date herewith.)

4.3       -    Unit Agreement Among American  Mobile Satellite Corporation, AMSC
               Acquisition Company, Inc. and State Street Bank and Trust Company
               as Unit Agent, dated March 31, 1998 (Incorporated by reference to
               Registration Statement on Form S-4 filed on even date herewith.)

4.4       -    Warrant Agreement  between American Mobile Satellite  Corporation
               as Issuer  and State  Street  Bank and Trust  Company  as Warrant
               Agent  dated  March  31,  1998   (Incorporated  by  reference  to
               Registration Statement on Form S-4 filed on even date herewith.)

4.5       -    Warrant Registration Rights Agreement dated March 31, 1998 By and
               Among American Mobile Satellite  Corporation and Bear,  Stearns &
               Co. Inc., J.P. Morgan  Securities  Inc.,  T.D.  Securities  (USA)
               Inc.,  BancAmerica Robertson Stephens  (Incorporated by reference
               to  Registration  Statement  on  Form  S-4  filed  on  even  date
               herewith.)

4.6       -    Pledge  and  Security  Agreement  by and among  AMSC  Acquisition
               Company,  Inc.,  State Street Bank and Trust Company,  as Trustee
               and State  Street Bank and Trust  Company,  as  Collateral  Agent
               dated March 31, 1998  (Incorporated  by reference to Registration
               Statement on Form S-4 filed on even date herewith.)

10.65     -    Stock  Purchase  Agreement for the  Acquisition of Motorola ARDIS
               Acquisition,  Inc. and Motorola ARDIS,  Inc. by AMSC  Acquisition
               Company,  Inc., a Wholly-  Owned  Subsidiary  of American  Mobile
               Satellite   Corporation,   Dated   as  of   December   31,   1997
               (Incorporated by reference to Exhibit 10.65 previously filed with
               the Report on Form 10-K for the period  ending  December 31, 1997
               (File No. 0-23044)).

10.65(a)  -    Amendment  No.  1dated  March  31,  1998  to the  Stock  Purchase
               Agreement for the Acquisition of Motorola ARDIS Acquisition, Inc.
               and Motorola ARDIS,  Inc. by AMSC  Acquisition  Company,  Inc., a
               Wholly-Owned  Subsidiary of American Mobile Satellite Corporation
               (Incorporated  by  reference  to Exhibit 4.2 to the  Schedule 13D
               dated March 31, 1998, filed by Motorola, Inc.)


<PAGE>

10.66     -    Participation  Rights  Agreement  by and  among  Motorola,  Inc.,
               American Mobile Satellite Corporation,  and the parties listed on
               Schedule  A,  dated as of  December  31,  1997  (Incorporated  by
               reference to Exhibit  10.66  previously  filed with the Report on
               Form 10-K for the  period  ending  December  31,  1997  (File No.
               0-23044)).

10.67     -    Registration  Rights  Agreement  by  and  among  Motorola,  Inc.,
               American Mobile Satellite  Corporation dated as of March 31, 1998
               (Incorporated  by  reference  to Exhibit 4.4 to the  Schedule 13D
               dated March 31, 1998, filed by Motorola, Inc.)

10.68     -    Guaranty  Issuance  Agreement,  dated as of March 31, 1998, among
               Hughes  Electronics  Corporation,   Singapore  Telecommunications
               Ltd.,  and Baron  Capital  Partners,  L.P.  and  American  Mobile
               Satellite   Corporation  and  AMSC  Acquisition   Company,   Inc.
               (Incorporated by reference to Exhibit 1 to the Schedule 13D dated
               March  31,  1998,  filed  by  Hughes   Communications   Satellite
               Services, Inc. )

10.69     -    Warrant for the  Purchase  of Shares of Common  Stock of American
               Mobile  Satellite  Corporation,   dated  as  of  March  31,  1998
               (Incorporated by reference to Exhibit 2 to the Schedule 13D dated
               March  31,  1998,  filed  by  Hughes   Communications   Satellite
               Services, Inc. )

10.70     -    Amended and Restated  Registration Rights Agreement,  dated as of
               March 31, 1998, among American Mobile  Satellite  Corporation and
               Hughes  Electronics  Corporation,   Singapore  Telecommunications
               Ltd., and Baron Capital Partners, L.P. (Incorporated by reference
               to Exhibit 3 to the Schedule  13D dated March 31, 1998,  filed by
               Hughes Communications Satellite Services, Inc.)

10.71     -    Amendment No. 2 to the Warrant Certificate, dated as of March 31,
               1998, by and among  American  Mobile  Satellite  Corporation  and
               Hughes  Electronics  Corporation,   Singapore  Telecommunications
               Ltd., and Baron Capital Partners, L.P. (Incorporated by reference
               to Exhibit 4 to the Schedule  13D dated March 31, 1998,  filed by
               Hughes Communications Satellite Services, Inc. )

10.72     -    Term Credit  Agreement  dated as of March 31, 1998 among American
               Mobile  Satellite  Corporation,  Morgan Guaranty Trust Company of
               New York,  Toronto Dominion  (Texas),  Inc. and other banks party
               thereto (filed herewith.)

10.73     -    Revolving  Credit Agreement dated as of March 31, 1998 among AMSC
               Acquisition Company, Inc., American Mobile Satellite Corporation,
               Morgan  Guaranty  Trust Company of New York and Toronto  Dominion
               (Texas), Inc. and other banks party thereto (filed herewith.)

11.1      -    Computations of Earning Per Common Share (filed herewith)

27.0      -    Financial Data Schedule (filed herewith)






                                                                 EXHIBIT 10.72

                                                               [EXECUTION COPY]





                                  $100,000,000


                              TERM CREDIT AGREEMENT


                                   dated as of


                                 March 31, 1998



                                      among


                     American Mobile Satellite Corporation,


                            The Banks Listed Herein,


                   Morgan Guaranty Trust Company of New York,
                             as Documentation Agent,


                                       and


                         Toronto Dominion (Texas), Inc.,
                             as Administrative Agent






<PAGE>

                                                                          PAGE

                                TABLE OF CONTENTS

                             ----------------------

                                                                          PAGE

                                    ARTICLE 1
                                   DEFINITIONS

SECTION 1.01.  Definitions...................................................1
SECTION 1.02.  Accounting Terms and Determinations..........................20

                                    ARTICLE 2
                                   THE CREDITS

SECTION 2.01.  Commitments to Lend..........................................21
SECTION 2.02.  Method of Borrowing..........................................21
SECTION 2.03.  Notes........................................................22
SECTION 2.04.  Maturity of Loans; Mandatory Prepayments.....................23
SECTION 2.05.  Interest Rates...............................................24
SECTION 2.06.  Method of Electing Interest Rates............................25
SECTION 2.07.  Mandatory Termination and Reduction of Commitments...........27
SECTION 2.08.  Optional Prepayments.........................................27
SECTION 2.09.  General Provisions as to Payments............................28
SECTION 2.10.  Funding Losses...............................................28
SECTION 2.11.  Computation of Interest and Fees.............................29
SECTION 2.12.  Extension of Maturity Date...................................29

                                    ARTICLE 3
                                   CONDITIONS

SECTION 3.01.  Closing......................................................29
SECTION 3.02.  Borrowings...................................................32

                                    ARTICLE 4
                         REPRESENTATIONS AND WARRANTIES

SECTION 4.01.  Corporate Existence and Power................................33
SECTION 4.02.  Corporate Authorization; No Contravention....................33
SECTION 4.03.  Government Approvals.........................................33
SECTION 4.04.  Binding Effect...............................................34
SECTION 4.05.  Litigation...................................................34
SECTION 4.06.  No Default...................................................34




                                        i

<PAGE>


                                                                          PAGE

SECTION 4.07.  ERISA Compliance.............................................34
SECTION 4.08.  Title to Property............................................36
SECTION 4.09.  Taxes........................................................36
SECTION 4.10.  Financial Condition..........................................36
SECTION 4.11.  Environmental Matters........................................37
SECTION 4.12.  Regulated Entities...........................................37
SECTION 4.13.  Subsidiaries.................................................37
SECTION 4.14.  Insurance....................................................37
SECTION 4.15.  Business.....................................................38
SECTION 4.16.  Collateral; Property.........................................38
SECTION 4.17.  Security and Pledge Agreement................................38
SECTION 4.18.  Disclosure...................................................38

                                    ARTICLE 5
                                    COVENANTS

SECTION 5.01.  Information..................................................39
SECTION 5.02.  Certificates; Other Information..............................40
SECTION 5.03.  Notices......................................................40
SECTION 5.04.  Conduct of Business; Preservation of Corporate Existence.....42
SECTION 5.05.  Maintenance of Property......................................42
SECTION 5.06.  Maintenance of Insurance.....................................42
SECTION 5.07.  Payment of Obligations.......................................43
SECTION 5.08.  Compliance with Laws.........................................43
SECTION 5.09.  Inspection of Property and Books and Records.................43
SECTION 5.10.  Environmental Laws...........................................44
SECTION 5.11.  Use of Proceeds..............................................44
SECTION 5.12.  Security and Pledge Agreement................................44
SECTION 5.13.  No Subsidiaries..............................................44
SECTION 5.14.  FCC Approval.................................................44
SECTION 5.15.  Government Approvals.........................................45
SECTION 5.16.  Further Assurances...........................................45
SECTION 5.17.  Limitation on Liens..........................................46
SECTION 5.18.  Disposition of Assets, Consolidations and Mergers............47
SECTION 5.19.  Employee Contracts and Arrangements..........................49
SECTION 5.20.  Investments..................................................49
SECTION 5.21.  Transactions with Affiliates.................................49
SECTION 5.22.  Compliance with ERISA........................................49
SECTION 5.23.  Restricted Payments..........................................50




                                       ii

<PAGE>


                                                                          PAGE

SECTION 5.24.  Accounting Changes...........................................50
SECTION 5.25.  Limitation on Indebtedness...................................50

                                    ARTICLE 6
                                    DEFAULTS

SECTION 6.01.  Events of Default............................................51
SECTION 6.02.  Notice of Default............................................56

                                    ARTICLE 7
                                   THE AGENTS

SECTION 7.01.  Appointment and Authorization................................56
SECTION 7.02.  Agents and Affiliates........................................56
SECTION 7.03.  Action by Agents.............................................56
SECTION 7.04.  Consultation with Experts....................................56
SECTION 7.05.  Liability of Agents..........................................57
SECTION 7.06.  Indemnification..............................................57
SECTION 7.07.  Credit Decision..............................................57
SECTION 7.08.  Successor Agent..............................................57
SECTION 7.09.  Agents' Fees.................................................58

                                    ARTICLE 8
                             CHANGE IN CIRCUMSTANCES

SECTION 8.01.  Basis for Determining Interest Rate Inadequate or Unfair.....58
SECTION 8.02.  Illegality...................................................59
SECTION 8.03.  Increased Cost and Reduced Return............................59
SECTION 8.04.  Taxes........................................................61
SECTION 8.05.  Base Rate Loans Substituted for Affected Euro-Dollar
               Loans........................................................63

                                    ARTICLE 9
                                  MISCELLANEOUS

SECTION 9.01.  Notices......................................................63
SECTION 9.02.  No Waivers...................................................64
SECTION 9.03.  Expenses; Indemnification....................................64
SECTION 9.04.  Sharing of Set-offs..........................................64




                                       iii

<PAGE>


                                                                          PAGE

SECTION 9.05.  Amendments and Waivers.......................................65
SECTION 9.06.  Successors and Assigns.......................................65
SECTION 9.07.  Collateral...................................................67
SECTION 9.08.  Governing Law; Submission to Jurisdiction....................67
SECTION 9.09.  Counterparts; Integration; Effectiveness.....................68
SECTION 9.10.  Waiver of Jury Trial.........................................68
SECTION 9.11.  Confidentiality..............................................68

COMMITMENT SCHEDULE
PRICING SCHEDULE
DISCLOSURE SCHEDULE
EXHIBIT A - Note
EXHIBIT B - Opinion of Counsel for the  Borrower  
EXHIBIT C - Opinion of Special Counsel for the Agents 
EXHIBIT D - Assignment and Assumption Agreement





                                       iv

<PAGE>



                              TERM CREDIT AGREEMENT


         AGREEMENT  dated as of March 31, 1998 among AMERICAN  MOBILE  SATELLITE
CORPORATION,  the BANKS listed on the signature  pages hereof,  MORGAN  GUARANTY
TRUST COMPANY OF NEW YORK, as Documentation Agent, and TORONTO DOMINION (TEXAS),
INC., as Administrative Agent.

         The parties hereto agree as follows:



                                    ARTICLE 1
                                   DEFINITIONS

          SECTION 1.01.  Definitions.  The following terms, as used herein, have
the following meanings:

         "ACTEL" means African Continental Telecommunications Ltd.

         "ACTEL   Agreement"   means  the   agreement   among  AMSC   Subsidiary
Corporation,  the Borrower and ACTEL, dated as of December 2, 1997,  pursuant to
which AMSC Acquisition will lease its MSAT-2 Satellite to ACTEL, as in effect on
the Effective Date.

         "Acquisition" means the acquisition by AMSC Acquisition Company of 100%
of the capital  stock or other equity  interests of ARDIS  pursuant to the ARDIS
Purchase Agreement.

         "Adjusted London Interbank Offered Rate" has the meaning set forth in
Section 2.05(b).

          "Administrative  Agent" means Toronto  Dominion  (Texas),  Inc. in its
capacity as administrative agent for the Banks hereunder,  and its successors in
such capacity.

         "Administrative  Questionnaire"  means,  with respect to each Bank,  an
administrative  questionnaire in the form prepared by the  Administrative  Agent
and submitted to the  Administrative  Agent (with a copy to the  Borrower)  duly
completed by such Bank.




                                        1

<PAGE>



         "Affiliate" means, as to any Person,  any other Person which,  directly
or  indirectly,  is in control of, is controlled  by, or is under common control
with,  such Person.  A Person shall be deemed to control  another  Person if the
controlling  Person  possesses,  directly or indirectly,  the power to direct or
cause the direction of the management and policies of the other Person,  whether
through the ownership of voting  securities,  by contract or otherwise.  Without
limitation,  any director,  executive officer or beneficial owner of 25% or more
of the equity of a Person shall,  for the purposes of this Agreement,  be deemed
to control the other Person,  and each Shareholder  Guarantor shall be deemed to
be an Affiliate.

         "Agents" means the  Administrative  Agent and the Documentation  Agent,
and "Agent" means either of the foregoing.

         "AMRC Holdings" means AMRC Holdings, Inc., a Delaware corporation,
and its successors

         "AMSC  Acquisition  Company" means AMSC  Acquisition  Company,  Inc., a
Delaware corporation, and its successors.

         "Applicable Lending Office" means, with respect to any Bank, (i) in the
case of its Base Rate Loans, its Domestic Lending Office and (ii) in the case of
its Euro-Dollar Loans, its Euro-Dollar Lending Office.

         "ARDIS"  means,  collectively,  Motorola  ARDIS  Acquisition,  Inc.,  a
Delaware  corporation,  Motorola  ARDIS,  Inc.,  a Delaware  corporation,  ARDIS
Holding  Company,  a New York general  partnership,  Radio Data Network  Holding
Corporation,  a Delaware  corporation,  and ARDIS  Company,  a New York  general
partnership.

         "ARDIS Purchase  Agreement" means the Stock Purchase Agreement dated as
of December 31, 1997 among the  Borrower,  AMSC  Acquisition  Company,  Motorola
Inc., Motorola ARDIS Acquisition, Inc. and Motorola ARDIS, Inc.

         "Asset Sale" means any sale, lease or other disposition  (including any
such transaction  effected by way of merger or  consolidation  and the Satellite
Lease  Arrangements)  by the Borrower or any of its  Subsidiaries  of any asset,
including  without  limitation any  sale-leaseback  transaction,  whether or not
involving a capital lease,  but excluding (i)  dispositions of inventory,  cash,
cash equivalents and other cash management  investments and obsolete,  unused or
unnecessary  equipment and undeveloped real estate, in each case in the ordinary
course of business and (ii)  dispositions to the Borrower or a Subsidiary of the
Borrower.




                                        2

<PAGE>



         "Assignee" has the meaning set forth in Section 9.06(c).

         "Bank"  means each bank  listed on the  signature  pages  hereof,  each
Assignee which becomes a Bank pursuant to Section 9.06(c),  and their respective
successors.

         "Baron Capital" means Baron Capital Partners,  L.P., a Delaware limited
partnership.

         "Baron  Capital  Guaranty"  means the  Guaranty,  dated as of March 31,
1998, made by Baron Capital to the Administrative  Agent for its own benefit and
the benefit of the Banks, as the same may be amended from time to time.

         "Baron Capital Letter of Credit" means the Letter of Credit dated March
31, 1998 issued by The Bank of New York for the account of Baron Capital for the
benefit of the Administrative Agent on behalf of the Banks.

         "Base Rate" means, for any day, a rate per annum equal to the higher of
(i) the Prime  Rate for such day and (ii) the sum of 5/8 of 1% plus the  Federal
Funds Rate for such day.

         "Base Rate Loan" means (i) a Loan which bears interest at the Base Rate
pursuant  to the  applicable  Notice of  Borrowing  or Notice of  Interest  Rate
Election or the  provisions  of Article 8 or (ii) an overdue  amount which was a
Base Rate Loan immediately before it became overdue.

         "Borrower" means American Mobile Satellite Corporation, a Delaware
corporation, and its successors.

         "Borrower Group" means the Borrower and its Consolidated Subsidiaries.

         "Borrowing" means a borrowing hereunder consisting of Loans made to the
Borrower  on the same day  pursuant  to Article 2, all of which Loans are of the
same Type  (subject  to Article 8) and,  except in the case of Base Rate  Loans,
have the same initial Interest Period. A Borrowing is a "Base Rate Borrowing" if
such Loans are Base Rate Loans or a  "Euro-Dollar  Borrowing"  if such Loans are
Euro-Dollar Loans.

         "Capital Lease Obligations" means all monetary  obligations of a Person
under any leasing or similar  arrangement  which,  in  accordance  with GAAP, is
classified as a capital lease.

         "Cash Equivalents" means:




                                        3

<PAGE>



          (a)  securities  issued or fully  guaranteed  or insured by the United
States  Government or any agency thereof and backed by the full faith and credit
of the United States  having  maturities of not more than twelve months from the
date of acquisition;

          (b) certificates of deposit, time deposits,  Eurodollar time deposits,
or bankers' acceptances having in each case a tenor of not more than six months,
issued by any Bank, or by any U.S.  commercial bank having combined  capital and
surplus of not less than $500,000,000 whose short term securities are rated both
A-1 or higher by  Standard  & Poor's  Corporation  and P-1 or higher by  Moody's
Investors Services, Inc.;

          (c)  commercial  paper of an  issuer  rated  either  at  least  A-1 by
Standard & Poor's Ratings Group, a division of  McGraw-Hill,  Inc. and/or P-1 by
Moody's  Investors  Service  Inc.  and in either case having a tenor of not more
than three months;

          (d) repurchase agreements fully collateralized by securities issued by
United States Government agencies; and

          (e) money market mutual funds invested in the instruments permitted by
clauses (a), (b), (c) and (d) above.

         "CERCLA" has the meaning specified in the definition "Environmental
Laws".

         "Change In  Control"  means (i) any person or group of persons  (within
the  meaning of  Section 13 or 14 of the  Securities  Exchange  Act of 1934,  as
amended) (other than any Shareholder Guarantor,  AT&T Wireless Services, Inc. or
Motorola,  Inc.)  shall have  beneficial  ownership  (within the meaning of Rule
13d-3  promulgated by the Securities and Exchange  Commission under said Act) of
more than 25% of the  outstanding  capital  stock of the  Borrower,  (ii) Hughes
shall have  beneficial  ownership  of less than 25% of the  outstanding  capital
stock of the  Borrower,  except solely as a result of the issuance of additional
capital  stock by the  Borrower to Persons  other than  Hughes,  in which case a
Change of Control  under this clause (ii) shall not occur  unless  Hughes  shall
have beneficial  ownership of less than 10% of the outstanding  capital stock of
the  Borrower,  (iii)  during  any  period of 24  consecutive  calendar  months,
individuals  who were  directors of the Borrower on the first day of such period
shall cease to  constitute  a majority of the board of directors of the Borrower
(ignoring for this purpose replacements of  stockholder-designated  directors by
successor directors designated by the same stockholder or group of stockholders)
or (iv) the Borrower shall cease to own all of the outstanding  capital stock of
AMSC Acquisition Company.




                                        4

<PAGE>



         "Closing  Date" means the date on or after the Effective  Date on which
the  Documentation  Agent shall have  received  the  documents  specified  in or
pursuant to Section 3.01(a).

         "Code" means the Internal Revenue Code of 1986, as amended, or any
successor statute.

         "Collateral" means all property with respect to which Liens are created
or purported to be created pursuant to the Security and Pledge Agreement.

         "Commitment"  means any Tranche A  Commitment,  Tranche B Commitment or
Tranche C Commitment,  and "Commitments"  means any or all of the foregoing,  as
the context may require.

         "Commitment Schedule" means the Commitment Schedule attached hereto.

         "Communications  Asset"  means  a  terrestrial  or  satellite  antenna,
licensed site, base station,  communications ground segment,  network operations
center or other telecommunications facility (other than a satellite).

         "Consolidated   Capital   Expenditures"  means,  for  any  period,  the
additions to property,  plant and equipment of the Borrower and its Consolidated
Subsidiaries for such period, as determined in accordance with GAAP.

         "Consolidated  Current  Assets"  means  at any  date  the  consolidated
current assets of the Borrower and its Consolidated  Subsidiaries  determined as
of such date.

         "Consolidated   Current   Liabilities"   means  at  any  date  (i)  the
consolidated   current   liabilities  of  the  Borrower  and  its   Consolidated
Subsidiaries  plus  (ii) the  Contingent  Obligations  of the  Borrower  and its
Consolidated  Subsidiaries with respect to the current liabilities of any Person
(other than the Borrower and its Consolidated  Subsidiaries),  all determined as
of such date.

         "Consolidated  Net Working  Investment"  means at any date Consolidated
Current  Assets  (exclusive  of cash and cash  equivalents)  minus  Consolidated
Current Liabilities (exclusive of Indebtedness).

         "Consolidated  Subsidiary"  means at any date and with  respect  to any
Person,  any  Subsidiary  or  other  entity  the  accounts  of  which  would  be
consolidated with those of such Person in its consolidated  financial statements
if such statements were prepared as of such date.




                                        5

<PAGE>



         "Contingent  Obligation" means, as applied to any Person, any direct or
indirect  liability  of that Person  with  respect to any  Indebtedness,  lease,
dividend,  letter of credit or other  obligation (the "primary  obligations") of
another  Person (the "primary  obligor"),  including,  without  limitation,  any
obligation  of  that  Person,  whether  or  not  contingent,  (a)  to  purchase,
repurchase  or  otherwise  acquire  such  primary  obligations  or any  property
constituting direct or indirect security therefor,  or (b) to advance or provide
funds (i) for the payment or discharge of any such primary  obligation,  or (ii)
to  maintain  working  capital  or equity  capital  of the  primary  obligor  or
otherwise to maintain the net worth or solvency or any balance sheet item, level
of income or  financial  condition  of the primary  obligor,  or (c) to purchase
property, securities or services primarily for the purpose of assuring the owner
of any such  primary  obligation  of the ability of the primary  obligor to make
payment of such primary obligation,  or (d) otherwise to assure or hold harmless
the holder of any such primary  obligation  against loss in respect thereof,  or
(e) to purchase or otherwise acquire,  or otherwise to assure a creditor against
loss in respect of any Indebtedness. For purposes of this definition, the amount
of any  Contingent  Obligation  shall be  deemed  to be an  amount  equal to the
maximum reasonably anticipated liability in respect thereof.

         "Contractual  Obligation" means, as to any Person, any provision of any
security  issued by such  Person  or of any  agreement,  undertaking,  contract,
indenture, mortgage, deed of trust or other instrument, document or agreement to
which such Person is a party or by which it or any of its property is bound.

         "Controlled  Group" means the Borrower and all Persons  (whether or not
incorporated)  under  common  control or treated as a single  employer  with the
Borrower or any of its Subsidiaries  pursuant to Section 414(b), (c), (m) or (o)
of the Code.

         "Default"  means any condition or event which  constitutes  an Event of
Default  or which  with the  giving of  notice  or lapse of time or both  would,
unless cured or waived, become an Event of Default.

         "Disclosure  Schedule"  means  the  Disclosure  Schedule  of even  date
herewith attached hereto and hereby made part of this Agreement.

         "Documentation  Agent" means Morgan  Guaranty Trust Company of New York
in its  capacity  as  documentation  agent  for  the  Banks  hereunder,  and its
successors in such capacity.

         "dollars" means United States dollars.




                                        6

<PAGE>



         "Domestic  Business  Day"  means any day except a  Saturday,  Sunday or
other day on which  commercial  banks in New York City are  authorized by law to
close.

         "Domestic Lending Office" means, as to each Bank, its office located at
its address set forth in its Administrative  Questionnaire (or identified in its
Administrative  Questionnaire  as its  Domestic  Lending  Office)  or such other
office as such Bank may hereafter  designate as its Domestic  Lending  Office by
notice to the Borrower and the Administrative Agent.

         "Effective  Date" means the date this  Agreement  becomes  effective in
accordance with Section 9.09.

         "Environmental  Claim"  means  all  claims,  however  asserted,  by any
Governmental   Authority  or  other  Person  alleging  potential   liability  or
responsibility  for  violation  of any  Environmental  Law or for  injury to the
environment or threat to public health,  personal  injury  (including  sickness,
disease or death),  property  damage,  natural  resources  damage,  or otherwise
alleging  liability  or  responsibility  for damages  (punitive  or  otherwise),
cleanup,  removal,  remedial or response costs,  restitution,  civil or criminal
penalties,  injunctive relief, or other type of relief,  resulting from or based
upon (a) the  presence,  placement,  discharge,  emission or release  (including
intentional  and   unintentional,   negligent  and   non-negligent,   sudden  or
non-sudden,  accidental or non-accidental placements, spills, leaks, discharges,
emissions  or  releases)  of any  Hazardous  Material  at, in or from  property,
whether or not owned by the Borrower, or (b) any other circumstances forming the
basis of any violation, or alleged violation, of any Environmental Law.

         "Environmental  Laws" means all applicable  federal,  state,  local and
foreign  laws,  statutes,   common  law  duties,   judicial  decisions,   rules,
regulations,  ordinances, judgements and codes, together with all administrative
orders, requests, licenses,  authorizations and permits of, and agreements with,
any Governmental Authorities,  in each case relating to the environment,  health
and  safety  or to  emissions,  discharges  or  releases,  or  the  manufacture,
distribution,  use,  treatment,  storage,  disposal,  transport or handling,  of
pollutants, contaminants, wastes or toxic or hazardous substances; including, as
they may be amended from time to time, the Comprehensive Environmental Response,
Compensation  and  Liability  Act of 1980  ("CERCLA"),  the Clean  Air Act,  the
Federal Water  Pollution  Control Act of 1972, the Solid Waste Disposal Act, the
Federal Resource Conservation and Recovery Act, the Toxic Substances Control Act
and the Emergency Planning and the Community Right-to-Know Act of 1986.




                                        7

<PAGE>



         "ERISA" means the Employee  Retirement  Income Security Act of 1974, as
amended, or any successor statute.

         "ERISA Event" means (a) a Reportable  Event with respect to a Qualified
Plan or a  Multiemployer  Plan; (b) a withdrawal by any member of the Controlled
Group from a Qualified  Plan subject to Section 4063 of ERISA during a plan year
in which it was a  substantial  employer  (as defined in Section  4001(a)(2)  of
ERISA);  (c) a complete or partial  withdrawal  by any member of the  Controlled
Group  from a  Multiemployer  Plan;  (d) the  filing  of a notice  of  intent to
terminate, the treatment of a plan amendment as a termination under Section 4041
or 4041A of ERISA or the  commencement of proceedings by the PBGC to terminate a
Qualified Plan or Multiemployer Plan subject to Title IV of ERISA; (e) a failure
to make required contributions to a Qualified Plan or Multiemployer Plan; (f) an
event or condition  which might  reasonably  be expected to  constitute  grounds
under  Section 4042 of ERISA for the  termination  of, or the  appointment  of a
trustee  to  administer,  any  Qualified  Plan or  Multiemployer  Plan;  (g) the
imposition  of any liability  under Title IV of ERISA,  other than PBGC premiums
due but not  delinquent  under  Section  4007 of ERISA,  upon any  member of the
Controlled  Group;  (h) an application  for a funding waiver or any extension of
any amortization  period pursuant to Section 412 of the Code with respect to any
Qualified  Plan;  or (i)  any  member  of the  Controlled  Group  engages  in or
otherwise becomes liable for a non-exempt prohibited transaction.

         "Escrow  Letter" means the letter  agreement  dated March 31, 1998 from
the Borrower to the Banks and the Agents.

         "Euro-Dollar  Business  Day" means any  Domestic  Business Day on which
commercial  banks are open for  international  business  (including  dealings in
dollar deposits) in London.

         "Euro-Dollar Lending Office" means, as to each Bank, its office, branch
or   affiliate   located  at  its  address  set  forth  in  its   Administrative
Questionnaire  (or  identified  in  its  Administrative   Questionnaire  as  its
Euro-Dollar  Lending  Office) or such other office,  branch or affiliate of such
Bank as it may hereafter  designate as its Euro-Dollar  Lending Office by notice
to the Borrower and the Administrative Agent.

         "Euro-Dollar  Loan"  means  (i)  a  Loan  which  bears  interest  at  a
Euro-Dollar  Rate  pursuant to the  applicable  Notice of Borrowing or Notice of
Interest  Rate Election or (ii) an overdue  amount which was a Euro-Dollar  Loan
immediately before it became overdue.




                                        8

<PAGE>



         "Euro-Dollar  Margin"  means a rate per annum  determined in accordance
with the Pricing Schedule.

         "Euro-Dollar  Rate"  means a rate of  interest  determined  pursuant to
Section 2.05(b) on the basis of an Adjusted London Interbank Offered Rate.

         "Euro-Dollar Reserve Percentage" has the meaning set forth in Section
2.05(b).

         "Event of Default" has the meaning set forth in Section 6.01.

         "Excess Cash Flow" means, for any fiscal year of the Borrower,  (i) the
net income of the Borrower  and its  Consolidated  Subsidiaries  for such fiscal
year,  determined on a consolidated basis for such fiscal year, plus (ii) to the
extent  deducted  in  determining  such net  income,  the  aggregate  amount  of
depreciation and amortization and other similar non-cash charges for such fiscal
year,  plus (iii) to the extent  deducted in  determining  such net income,  the
aggregate  amount of income  tax  expense  (other  than cash  taxes  paid by the
Borrower and its Consolidated Subsidiaries during such fiscal year) plus (minus)
(iv) the amount, if any, of any decrease  (increase) in Consolidated Net Working
Investment between the beginning and the end of such year minus (v) Consolidated
Capital  Expenditures  for such fiscal year minus (vi) the  aggregate  amount of
scheduled   principal   payments  of   Indebtedness  of  the  Borrower  and  its
Consolidated Subsidiaries paid during such fiscal year by the Borrower or any of
its  Consolidated  Subsidiaries,  determined on a  consolidated  basis and minus
(vii) the Excess Cash Flow for AMSC  Acquisition  Company  and its  Consolidated
Subsidiaries  for such fiscal year, to the extent the Reduction  Percentage  (as
defined in the Revolving Credit  Agreement)  thereof is applied to the reduction
of the Commitments under the Revolving Credit Agreement.

         "Existing  Credit  Facilities"  means the $75,000,000  Credit Agreement
dated as of June 28, 1996 among AMSC Subsidiary  Corporation,  the Borrower, the
Banks  listed   therein,   Morgan   Guaranty  Trust  Company  of  New  York,  as
Documentation  Agent,  and Toronto  Dominion  (Texas),  Inc., as  Administrative
Agent,   together  with  the  Loan  Documents  referred  to  therein,   and  the
$150,000,000  Credit  Agreement  dated as of June 28, 1996 among AMSC Subsidiary
Corporation,  the Borrower,  the Banks listed  therein,  Morgan  Guaranty  Trust
Company of New York, as Documentation Agent, and Toronto Dominion (Texas), Inc.,
as Administrative Agent, together with the Loan Documents referred to therein.

         "FCC" means the Federal Communications Commission or any successor
thereto.




                                        9

<PAGE>



         "FCC  Licenses"  means  the  licenses   identified  in  the  Disclosure
Schedule, together with each other material FCC license obtained by the Borrower
or any Subsidiary of the Borrower.

         "Federal  Funds Rate" means,  for any day, the rate per annum  (rounded
upward,  if  necessary,  to the  nearest  1/100th  of 1%) equal to the  weighted
average of the rates on overnight Federal funds transactions with members of the
Federal  Reserve  System  arranged  by Federal  funds  brokers  on such day,  as
published by the Federal  Reserve Bank of New York on the Domestic  Business Day
next  succeeding  such  day,  provided  that (i) if such  day is not a  Domestic
Business  Day,  the  Federal  Funds Rate for such day shall be such rate on such
transactions on the next preceding  Domestic Business Day as so published on the
next succeeding  Domestic Business Day, and (ii) if no such rate is so published
on such next succeeding  Domestic  Business Day, the Federal Funds Rate for such
day shall be the average rate quoted to The Toronto-Dominion Bank on such day on
such transactions as determined by the Administrative Agent.

         "GAAP" means generally accepted accounting  principles set forth in the
opinions and pronouncements of the Accounting  Principles Board and the American
Institute of Certified Public  Accountants and statements and  pronouncements of
the Financial  Accounting Standards Board (or agencies with similar functions of
comparable stature and authority within the accounting  profession),  or in such
other  statements  by such other entity as may be in general use by  significant
segments  of  the  U.S.  accounting  profession,  which  are  applicable  to the
circumstances as of the date of determination.

         "Government Approvals" means any authorizations,  consents,  approvals,
licenses (including FCC licenses),  leases,  rulings,  permits,  tariffs, rates,
certifications, exemptions, filings or registrations by or with any Governmental
Authority required to be obtained or held by the Borrower.

         "Governmental  Authority" means any nation or government,  any state or
other political  subdivision  thereof,  any central bank (or similar monetary or
regulatory  authority) thereof,  any entity exercising  executive,  legislative,
judicial, regulatory or administrative functions of or pertaining to government,
and any  corporation  or other  entity  owned or  controlled,  through  stock or
capital ownership or otherwise, by any of the foregoing.

         "Group of Loans" means at any time a group of Loans  consisting  of (i)
all Loans which are Base Rate Loans at such time or (ii) all  Euro-Dollar  Loans
having the same Interest  Period at such time,  provided  that, if a Loan of any
particular Bank is




                                       10

<PAGE>



converted to or made as a Base Rate Loan  pursuant to Article 8, such Loan shall
be  included  in the same Group or Groups of Loans from time to time as it would
have been in if it had not been so converted or made.

         "Guaranty  Issuance  Agreement" means the Guaranty  Issuance  Agreement
dated  as of  March  31,  1998,  among  Hughes,  SingTel,  Baron  Capital,  AMSC
Acquisition Company and the Borrower.

         "Guaranty  Issuance  Agreement  Event of  Default"  has the meaning set
forth in the Guaranty Issuance Agreement.

         "Hazardous  Materials"  means all those  substances which are regulated
by, or which may form the  basis of  liability  under,  any  Environmental  Law,
including all substances  identified under any Environmental Law as a pollutant,
contaminant,  waste, solid waste,  hazardous  material,  hazardous  substance or
toxic  substance,  including  petroleum or any  petroleum  derived  substance or
byproduct.

         "Hughes" means Hughes Electronics Corporation, a Delaware corporation.

         "Hughes Bridge Loan Agreement" means the Bridge Loan Agreement dated as
of December 30, 1997 by and among AMSC Subsidiary Corporation,  the Borrower and
Hughes Communications Satellite Services, Inc.

         "Hughes Guaranty" means the Guaranty,  dated as of March 31, 1998, made
by Hughes to the Administrative Agent for its own benefit and the benefit of the
Banks, as the same may be amended from time to time.

         "Indebtedness"  of  any  Person  means  without  duplication,  (a)  all
indebtedness  for borrowed  money;  (b) all  obligations  issued,  undertaken or
assumed as the deferred purchase price of capital assets;  (c) all reimbursement
obligations  with  respect  to  surety  bonds,   letters  of  credit,   bankers'
acceptances  and similar  instruments  (in each case,  whether or not  matured),
excluding  performance bonds,  letters of credit and similar undertakings in the
ordinary  course  of  business  of  the  Borrower,   to  the  extent  that  such
undertakings  do not secure an  obligation  for  borrowed  money or the deferred
purchase  price of a capital  asset;  (d) all  obligations  evidenced  by notes,
bonds,  debentures or similar  instruments,  including  obligations so evidenced
incurred in connection with the  acquisition of property,  assets or businesses,
excluding  performance bonds,  letters of credit and similar undertakings in the
ordinary  course  of  business  of  the  Borrower,   to  the  extent  that  such
undertakings  do not secure an  obligation  for  borrowed  money or the deferred
purchase price of a capital asset; (e) all indebtedness created or arising under
any  conditional  sale or  other  title  retention  agreement,  or  incurred  as





                                       11

<PAGE>


financing,  in either case with respect to property acquired by the Person (even
though the rights and remedies of the seller or bank under such agreement in the
event of default are limited to repossession or sale of such property);  (f) all
Capital  Lease  Obligations;  (g)  all  net  obligations  with  respect  to Rate
Contracts; (h) sale-leaseback  financings;  (i) all Contingent Obligations;  and
(j) all Indebtedness  referred to in paragraphs (a) through (i) above secured by
any Lien upon or in property  (including  accounts and contract rights) owned by
such  Person,  even though such Person has not assumed or become  liable for the
payment  of  such  Indebtedness.  For  purposes  of  this  definition,  (i)  any
Indebtedness  of the  Borrower  to a  Subsidiary  of the  Borrower  and (ii) any
Indebtedness  of a Subsidiary of the Borrower to or from the Borrower or another
Subsidiary of the Borrower shall be excluded.

         "Indemnitee" has the meaning set forth in Section 9.03(b).

         "Interest  Period" means,  with respect to each  Euro-Dollar  Loan, the
period commencing on the date of borrowing specified in the applicable Notice of
Borrowing or on the date  specified in the  applicable  Notice of Interest  Rate
Election and ending one, two,  three or six months  thereafter,  as the Borrower
may elect in the applicable notice; provided that:

          (a) any Interest  Period which would  otherwise  end on a day which is
not a  Euro-Dollar  Business  Day  shall  be  extended  to the  next  succeeding
Euro-Dollar  Business Day unless such Euro-Dollar  Business Day falls in another
calendar  month,  in which  case  such  Interest  Period  shall  end on the next
preceding Euro-Dollar Business Day;

          (b) any Interest Period which begins on the last Euro-Dollar  Business
Day  of a  calendar  month  (or  on a day  for  which  there  is no  numerically
corresponding  day in the  calendar  month at the end of such  Interest  Period)
shall,  subject to clause (c) below, end on the last Euro-Dollar Business Day of
a calendar month; and

          (c) any Interest  Period which would  otherwise end after the Maturity
Date shall end on the Maturity Date.

         "Investment"  means any  investment in any Person,  whether by means of
share purchase, capital contribution,  loan, Contingent Obligation, time deposit
or otherwise (but not including any demand deposit).

         "Joint Venture" means any corporation,  association, partnership, joint
venture or other business entity of which more than 10% but of which 50% or less





                                       12

<PAGE>



of the voting stock or other equity interests is owned or controlled directly or
indirectly by the Borrower or any of its Subsidiaries.

         "Lien"  means  any  mortgage,  deed of  trust,  pledge,  hypothecation,
assignment,  charge or deposit  arrangement,  encumbrance,  lien  (statutory  or
other) or  preference,  priority  or other  security  interest  or  preferential
arrangement of any kind or nature  whatsoever  (including,  without  limitation,
those created by,  arising under or evidenced by any  conditional  sale or other
title  retention  agreement,  the  interest  of a lessor  under a Capital  Lease
Obligation, any financing lease having substantially the same economic effect as
any of the foregoing,  or the filing of any financing statement naming the owner
of the  asset to  which  such  lien  relates  as  debtor,  under  the UCC or any
comparable  law) and any  contingent  or other  agreement  to provide any of the
foregoing.

         "Loan" means any Tranche A Loan,  Tranche B Loan or Tranche C Loan, and
"Loans" means any or all of the foregoing, as the context may require.

         "Loan  Documents"  means  this  Agreement,   the  Security  and  Pledge
Agreement,  the Shareholder Guaranties,  the Baron Capital Letter of Credit, all
Rate  Contracts  between the Borrower  and any of the Banks and all  agreements,
instruments  and documents  executed and  delivered in  connection  herewith and
therewith, each as amended, supplemented, waived or otherwise modified from time
to time.

         "London Interbank Offered Rate" has the meaning set forth in Section
2.05(b).

         "Major Casualty Event" means any loss of or damage to property  through
one or more  related  events for which the  Borrower or any of its  Subsidiaries
receives  any  insurance  proceeds  under any casualty  insurance  policy or any
condemnation  of property (or any transfer or disposition of property in lieu of
condemnation)  for which the  Borrower  or any of its  Subsidiaries  receives  a
condemnation  award or other  compensation,  with respect to which the aggregate
amount of such proceeds, award or other compensation exceeds $1,000,000.

         "Major  Contractual  Obligations" means the obligations of the Borrower
or any Subsidiary  thereof under the ACTEL Lease  Agreement and the TMI Purchase
Agreement.

         "Material  Adverse  Effect"  means a material  adverse  change in, or a
material adverse effect upon, any of (a) the operations,  business,  properties,
condition  (financial or otherwise) of the Borrower Group taken as a whole;  (b)
the ability or prospective ability of the Borrower or any of its Subsidiaries to





                                       13

<PAGE>


perform under any Loan  Document or any Major  Contractual  Obligation;  (c) the
legality, validity, binding effect or enforceability of any Loan Document or (d)
the perfection or priority of any Lien granted to the Administrative Agent under
the Security and Pledge Agreement.

         "Maturity  Date"  means  March 31,  2003 (as such date may be  extended
pursuant to Section  2.12),  or, if such day is not a Euro-Dollar  Business Day,
the next succeeding  Euro-Dollar  Business Day unless such Euro-Dollar  Business
Day falls in another  calendar  month,  in which case the Maturity Date shall be
the next preceding Euro-Dollar Business Day.

         "MSAT-1" means the satellite that is the subject of the TMI Purchase
Agreement.

         "MSAT-2" means the satellite that is the subject of the ACTEL Lease
Agreement.

         "Multiemployer  Plan" means a "multiemployer  plan" (within the meaning
of  Section  4001(a)(3)  of ERISA) to which any member of the  Controlled  Group
makes,  is making,  or is obligated to make  contributions  or has made, or been
obligated to make, contributions.

         "Net Cash  Proceeds"  means,  with respect to any Reduction  Event,  an
amount equal to the cash proceeds  (including  lease  payments)  received by the
Borrower or any of its  Subsidiaries  (excluding  the proceeds  received by AMSC
Acquisition Company and its Subsidiaries to the extent the Reduction  Percentage
(as  defined  in the  Revolving  Credit  Agreement)  thereof  is  applied to the
reduction of the Commitments (as defined in the Revolving Credit Agreement) from
or in respect of such Reduction Event, less any out-of-pocket costs and expenses
(excluding  administrative  expenses and overhead)  reasonably  incurred by such
Person in respect of such Reduction Event; provided that Net Cash Proceeds shall
exclude  any  insurance  proceeds  received  by  the  Borrower  or  any  of  its
Subsidiaries  in respect of the loss of or damage to MSAT-2 and  required  to be
paid by the  Borrower  or such  Subsidiary  to ACTEL or its  permitted  assigns;
provided, further, that Net Cash Proceeds received by the Borrower or any of its
Subsidiaries  in respect of any period under the ACTEL Lease  Agreement shall be
reduced by the amount paid by the Borrower or such Subsidiary during such period
under the TMI Purchase  Agreement and, without  duplication,  the amount paid by
the Parent Guarantor or such Subsidiary during such period for up to $50,000,000
of  insurance  for MSAT-1  required to be obtained  hereunder  or required to be
obtained by the Shareholder Guarantors.




                                       14

<PAGE>



         "Notes" means  promissory  notes of the Borrower,  substantially in the
form of Exhibit A hereto, evidencing the obligation of the Borrower to repay the
Loans, and "Note" means any one of such promissory notes issued hereunder.

         "Notice of Borrowing" has the meaning set forth in Section 2.02(a).

         "Notice of Interest Rate Election" has the meaning set forth in Section
2.06(a).

         "Notice  of Lien"  means  any  "notice  of lien"  or  similar  document
intended to be filed or recorded with any court,  registry,  recorder's  office,
central filing office or  Governmental  Authority for the purpose of evidencing,
creating,  perfecting or preserving the priority of a Lien securing  obligations
owing to a Governmental Authority.

         "Obligations" means all Loans, and other Indebtedness, advances, debts,
liabilities,  and obligations,  owing by the Borrower to any Bank, any Agent, or
any other Person required to be indemnified under any Loan Document, of any kind
or nature,  present or future, whether or not evidenced by any note, guaranty or
other instrument,  arising under this Agreement,  under any other Loan Document,
whether  or not for the  payment  of  money,  whether  arising  by  reason of an
extension of credit,  loan,  guaranty,  indemnification  or in any other manner,
whether direct or indirect (including those acquired by assignment), absolute or
contingent,  due or to become due, now existing or hereafter arising and however
acquired.

         "Offering  Memorandum" means the Preliminary  Offering Memorandum dated
March 9, 1998  relating  to units  consisting  of Senior  Notes and  warrants to
purchase common stock of the Borrower.

         "Parent" means, with respect  to any Bank, any Person  controlling such
Bank.

         "Participant" has the meaning set forth in Section 9.06(b).

         "PBGC" means the Pension  Benefit  Guaranty  Corporation  or any entity
succeeding to any or all of its functions under ERISA.

         "Permitted Liens" has the meaning set forth in Section 5.17.

         "Person"  means an  individual,  a  corporation,  a  limited  liability
company,  a  partnership,  an  association,  a  trust  or any  other  entity  or
organization,  including a government or political  subdivision  or an agency or
instrumentality thereof.




                                       15

<PAGE>



         "Plan"  means an employee  benefit  plan (as defined in Section 3(3) of
ERISA)  which any member of the  Controlled  Group  sponsors or  maintains or to
which  any  member  of the  Controlled  Group  makes  or is  obligated  to  make
contributions and includes any Multiemployer Plan or Qualified Plan.

         "Pricing Schedule" means the Pricing Schedule attached hereto.

         "Prime  Rate"  means the rate of  interest  publicly  announced  by The
Toronto-Dominion Bank in New York City from time to time as its Prime Rate.

         "Principal  Subsidiary"  means  at  any  time  any  Subsidiary  of  the
Borrower,  except  Subsidiaries  which at such time have been  designated by the
Borrower (by notice to the Administrative  Agent, which may be amended from time
to time) as  nonmaterial  and which,  if aggregated  and  considered as a single
subsidiary,  would  not  meet  the  definition  of  a  "significant  subsidiary"
contained as of the date hereof in Regulation S-X of the Securities and Exchange
Commission.

         "Qualified  Plan" means a pension  plan (as defined in Section  3(2) of
ERISA) intended to be  tax-qualified  under Section 401(a) of the Code and which
any member of the Controlled Group sponsors,  maintains, or to which it makes or
is obligated to make  contributions or has made contributions at any time during
the  immediately  preceding  period  covering at least five (5) plan years,  but
excluding any Multiemployer Plan.

         "Quarterly Date" means March 31, June 30, September 30 and December 31.

         "Rate Contracts" means interest rate and currency swap agreements, cap,
floor and collar agreements,  interest rate insurance, currency spot and forward
contracts and other  agreements or arrangements  designed to provide  protection
against fluctuations in interest or currency exchange rates;  provided that such
agreements or arrangements are documented under master netting agreements.

         "Reduction  Event"  means (i) any Asset Sale,  (ii) the issuance of any
equity securities by the Borrower or any of its Subsidiaries  (other than equity
securities (x) issued pursuant to any stock option, stock purchase or other plan
intended to benefit or compensate  the  officers,  directors or employees of the
Borrower or any Principal  Subsidiary,  but only to the extent that the Net Cash
Proceeds thereof in any fiscal year of the Borrower do not exceed the sum of (A)
$2,000,000  plus (B) the  aggregate  amount by which such Net Cash Proceeds were
less than  $2,000,000  in each prior fiscal year of the Borrower  after the date





                                       16

<PAGE>


hereof,  (y) issued to the Borrower or any of its  Subsidiaries or (z) issued by
AMRC  Holdings or any of its  Subsidiaries)  or (iii) the  occurrence of a Major
Casualty  Event.  The description of any transaction as falling within the above
definition does not affect any limitation on such transaction imposed by Article
5 of this Agreement.

         "Reduction  Percentage"  means (i) in respect  of an Asset Sale  (other
than the Satellite Lease  Arrangements) or a Major Casualty Event, 100%, (ii) in
respect of the Satellite Lease  Arrangements,  100% for the first $25,000,000 of
Net Cash Proceeds with respect  thereto and 75% for any such additional Net Cash
Proceeds,  (iii) in respect of Excess Cash Flow,  100% or (iv) in respect of the
issuance of equity  securities (other than (x) to a member of the Borrower Group
or (y) to a Shareholder  Guarantor as part of a private placement to one or more
Shareholder Guarantors) by the Borrower or any Subsidiary thereof, 50%.

         "Reference Banks" means the principal London offices of Morgan Guaranty
Trust Company of New York, The Toronto-Dominion Bank and any other Bank which is
appointed a Reference Bank by the Agents after  consultation  with the Borrower,
and "Reference Bank" means any one of such Reference Banks.

         "Regulation  U" means  Regulation  U of the Board of  Governors  of the
Federal Reserve System, as in effect from time to time.

         "Reportable Event" means any of the events set forth in Section 4043 of
ERISA or the  regulations  thereunder,  a  withdrawal  from a Plan  described in
Section 4063 of ERISA, or a cessation of operations described in Section 4062(e)
of ERISA.

         "Required  Banks"  means at any time Banks  having more than 50% of the
aggregate  amount of the  Commitments  or, if the  Commitments  shall  have been
terminated,  holding  Notes  evidencing  more than 50% of the  aggregate  unpaid
principal amount of the Loans.

         "Requirement  of Law" means,  as to any Person,  any law  (statutory or
common),  treaty,  rule or regulation or  determination of an arbitrator or of a
Governmental Authority, in each case applicable to or binding upon the Person or
any of its property or to which the Person or any of its property is subject; in
any case,  non-compliance  with which by the Borrower or any of its Subsidiaries
could reasonably be expected to have a Material Adverse Effect.

         "Responsible  Officer"  means,  with  respect to any Person,  the Chief
Executive  Officer,  the President or a duly  authorized Vice President or, with
respect to financial matters,  the Chief Financial Officer or the Treasurer,  of
such Person.




                                       17

<PAGE>



         "Revolving Credit Agreement" means the Credit Agreement dated as of the
date hereof among the Borrower,  AMSC  Acquisition  Company,  the Agents and the
other banks party thereto, as the same may be amended, supplemented, restated or
otherwise modified from time to time.

         "Sales Corporation" means American Mobile Satellite  Sales Corporation,
a Delaware corporation.

         "Satellite  Lease  Arrangements"  means  the sale or  lease  of  MSAT-2
pursuant to the ACTEL Lease  Agreement or a  replacement  agreement  (an "MSAT-2
Lease  Agreement")  provided  that any such  replacement  agreement  shall be on
commercially  reasonable terms, and provided that (A) the consideration received
by AMSC Acquisition in respect of such sale or lease (x) consists solely of cash
and (y)  constitutes  fair market value (as determined by the Board of Directors
of  AMSC  Acquisition  set  forth  in a  resolution  thereof  delivered  to  the
Administrative  Agent,  which  determination  shall be based  upon an opinion or
appraisal  issued  by an  appraisal  or  investment  banking  firm  of  national
standing);  (B) AMSC Acquisition shall have acquired (through purchase or lease)
capacity on MSAT-1 or a reasonable substitute thereof either (x) pursuant to the
TMI Purchase  Agreement or (y) any other agreement with a term not less than the
maximum  term of the MSAT-2  Lease  Agreement  then in effect and  otherwise  on
commercially reasonable terms if (in the case of this clause (y)) in the opinion
of a nationally recognized independent expert (a) the capacity acquired pursuant
to such  replacement  agreement  is  sufficient  to permit AMSC  Acquisition  to
conduct its operations as conducted and as contemplated to be conducted  through
the  term of the  MSAT-2  Lease  Agreement  then  in  effect  and (b) the  total
consideration  paid by AMSC Acquisition for such replacement  satellite capacity
is no greater than the fair market value thereof.

         "Secured Parties" means the Agents and the Banks.

         "Security and Pledge Agreement" means the Security and Pledge Agreement
dated as of March 31, 1998 between the Borrower and the Administrative Agent.

         "Senior  Notes" means AMSC  Acquisition  Company's 12 1/4% Senior Notes
due 2008.

         "Shareholder  Guarantor  Security  Agreement"  means the  Reimbursement
Security  and Pledge  Agreement  dated as of March 31, 1998 between the Borrower
and Hughes.




                                       18

<PAGE>



         "Shareholder Guarantors" means Hughes, SingTel and Baron Capital.

         "Shareholder   Guaranties"  means  the  Hughes  Guaranty,  the  SingTel
Guaranty and the Baron Capital Guaranty.

         "SingTel"  means  Singapore   Telecommunications  Ltd.,  a  corporation
organized under the laws of Singapore.

         "SingTel Guaranty" means the Guaranty, dated as of March 31, 1998, made
by SingTel to the  Administrative  Agent for its own  benefit and the benefit of
the Banks, as the same may be amended from time to time.

         "Subsidiary"  means, as to any Person,  any corporation or other entity
of which securities or other ownership interests having ordinary voting power to
elect a majority of the board of directors or other persons  performing  similar
functions are at the time directly or indirectly owned by such Person.

         "TMI Purchase  Agreement" means the Satellite  Purchase Agreement dated
as  of  December  4,  1997  between  TMI  Communications  and  Company,  Limited
Partnership and the Borrower.

         "Tranche A  Commitment"  means (i) with  respect to each Bank listed on
the  Commitment  Schedule,  the  amount  set forth  opposite  its name under the
heading "Tranche A Commitments" in the Commitment Schedule and (ii) with respect
to any  Assignee,  the  amount of the  transferor  Bank's  Tranche A  Commitment
assigned to such Assignee pursuant to Section 10.06, in each case as such amount
may be changed as a result of an assignment pursuant to Section 10.06.

         "Tranche B  Commitment"  means (i) with  respect to each Bank listed on
the  Commitment  Schedule,  the  amount  set forth  opposite  its name under the
heading "Tranche B Commitments" in the Commitment Schedule and (ii) with respect
to any  Assignee,  the  amount of the  transferor  Bank's  Tranche B  Commitment
assigned to such Assignee pursuant to Section 10.06, in each case as such amount
may be changed as a result of an assignment pursuant to Section 10.06.

         "Tranche C  Commitment"  means (i) with  respect to each Bank listed on
the  Commitment  Schedule,  the  amount  set forth  opposite  its name under the
heading "Tranche C Commitments" in the Commitment Schedule and (ii) with respect
to any  Assignee,  the  amount of the  transferor  Bank's  Tranche C  Commitment
assigned to such Assignee pursuant to Section 10.06, in each case as such amount
may be changed as a result of an assignment pursuant to Section 10.06.




                                       19

<PAGE>



         "Tranche A Loan" means a loan made by a Bank  pursuant to Section  2.01
as a Tranche A Loan.

         "Tranche B Loan" means a loan made by a Bank  pursuant to Section  2.01
as a Tranche B Loan.

         "Tranche C Loan" means a loan made by a Bank  pursuant to Section  2.01
as a Tranche C Loan.

         "Type",  when used in  reference  to any Loan or  Borrowing,  refers to
whether  the rate of  interest on such Loan,  or on the Loans  compromising  the
Borrowing, is determined by reference to the Euro-Dollar Rate or the Base Rate.

         "UCC"  means  the   Uniform   Commercial  Code  as  in  effect  in  any
jurisdiction.

         "Unfunded  Pension  Liabilities"  means the excess of a Plan's  accrued
benefits,  as defined in Section 3(23) of ERISA,  over the current value of that
Plan's assets, as defined in Section 3(26) of ERISA.

         "United  States"  means the United  States of  America,  including  the
States  and  the  District  of  Columbia,  but  excluding  its  territories  and
possessions.

         "Vendor Financing Indebtedness" means Indebtedness incurred by a member
of the Parent  Guarantor  Group the  proceeds  of which are  utilized  solely to
acquire ground-based Communications Assets.

         "Withdrawal  Liabilities"  means,  as of any  determination  date,  the
aggregate amount of the liabilities,  if any,  pursuant to Section 4201 of ERISA
if the Controlled Group made a complete  withdrawal from all Multiemployer Plans
and any increase in contributions pursuant to Section 4243 of ERISA.

         SECTION 1.02.  Accounting  Terms and  Determinations.  Unless otherwise
specified  herein,  all accounting  terms used herein shall be interpreted,  all
accounting  determinations hereunder shall be made, and all financial statements
required to be delivered  hereunder shall be prepared in accordance with GAAP as
in effect from time to time,  applied on a basis consistent  (except for changes
concurred in by the Borrower's  independent  public  accountants)  with the most
recent audited consolidated or combined financial statements of the Borrower and
its  Consolidated  Subsidiaries,  delivered to the Banks;  provided that, if the
Borrower  notifies  the  Administrative  Agent  that  it  wishes  to  amend  the
definition of "Excess Cash Flow" in Section 1.01 or any covenant in Article 5 to





                                       20

<PAGE>


eliminate the effect of any change in GAAP on the operation of such covenant (or
if the  Administrative  Agent notifies the Borrower that the Required Banks wish
to amend  Section  1.01 or  Article  5 for such  purpose),  then the  Borrower's
compliance with such covenant shall be determined on the basis of GAAP in effect
immediately  before the relevant change in GAAP became  effective,  until either
such notice is withdrawn or such covenant is amended in a manner satisfactory to
the Borrower and the Required Banks.



                                    ARTICLE 2
                                   THE CREDITS

         SECTION 2.01.  Commitments to Lend. Each Bank severally  agrees, on the
terms and conditions set forth in this Agreement, to lend to the Borrower on the
Closing  Date an  amount  not to  exceed  the  amount  of its  Commitments.  The
Borrowing  under  this  Section  shall be in an  aggregate  principal  amount of
$5,000,000 or any larger multiple of $1,000,000,  shall be made from the several
Banks ratably in proportion to their respective Commitments and shall be made by
each Bank as  Tranche A Loans,  Tranche B Loans and  Tranche C Loans  ratably in
proportion  to its  Tranche A  Commitment,  Tranche B  Commitment  and Tranche C
Commitment.  The Commitments are not revolving in nature,  and amounts repaid or
prepaid may not be reborrowed.

         SECTION  2.02.  Method of  Borrowing.  (a) The Borrower  shall give the
Administrative  Agent irrevocable  telephonic notice,  confirmed  immediately in
writing  (a  "Notice of  Borrowing"),  not later than 10:30 A.M.  (New York City
time) on (x) the  Domestic  Business Day before the  Borrowing,  if it is a Base
Rate Borrowing, and (y) the third Euro-Dollar Business Day before the Borrowing,
if it is a Euro-Dollar Borrowing, specifying:

          (i) the date of the Borrowing,  which shall be a Domestic Business Day
          in the case of a Base Rate Borrowing or a Euro-Dollar  Business Day in
          the case of a Euro-Dollar Borrowing;

          (ii) the aggregate amount of the Borrowing;

          (iii) whether the Loans  comprising the Borrowing are to bear interest
          initially at the Base Rate or a Euro-Dollar Rate; and

          (iv) in the  case of a  Euro-Dollar  Borrowing,  the  duration  of the
          Interest Period applicable  thereto,  subject to the provisions of the
          definition of Interest Period.




                                       21

<PAGE>




          (b) Upon receipt of the Notice of Borrowing,  the Administrative Agent
shall promptly notify each Bank of the contents thereof,  of such Bank's ratable
share of the  Borrowing  and of the  portion  thereof  which  shall be made as a
Tranche A Loan, a Tranche B Loan and a Tranche C Loan.

          (c) Not later  than 12:00 Noon (New York City time) on the date of the
Borrowing, each Bank shall make available its ratable share of the Borrowing, in
Federal  or  other  funds  immediately  available  in  New  York  City,  to  the
Administrative  Agent at its  address  referred to in Section  5.03.  Unless the
Administrative  Agent  determines  that any  applicable  condition  specified in
Article 3 has not been satisfied,  the Administrative  Agent will make the funds
so received  from the Banks  available  to the  Borrower  at the  Administrative
Agent's aforesaid address.

          (d) Unless the Administrative  Agent shall have received notice from a
Bank prior to the date of the Borrowing  that such Bank will not make  available
to  the   Administrative   Agent  such  Bank's  share  of  the  Borrowing,   the
Administrative  Agent may assume that such Bank has made such share available to
the  Administrative  Agent  on the  date of the  Borrowing  in  accordance  with
subsection  (c) of this  Section and the  Administrative  Agent may, in reliance
upon  such   assumption,   make  available  to  the  Borrower  on  such  date  a
corresponding amount. If and to the extent that such Bank shall not have so made
such share  available to the  Administrative  Agent,  such Bank and the Borrower
severally  agree to repay to the  Administrative  Agent forthwith on demand such
corresponding  amount together with interest thereon, for each day from the date
such  amount is made  available  to the  Borrower  until the date such amount is
repaid to the Administrative  Agent, at (i) in the case of the Borrower,  a rate
per annum equal to the higher of the Federal  Funds Rate and the  interest  rate
applicable  thereto  pursuant to Section 2.05 and (ii) in the case of such Bank,
the Federal  Funds Rate.  If such Bank shall repay to the  Administrative  Agent
such  corresponding  amount,  such amount so repaid shall constitute such Bank's
Loan included in the Borrowing for purposes of this Agreement.

         SECTION  2.03.  Notes.  (a) The  Tranche  A Loans,  Tranche B Loans and
Tranche C Loans of each Bank shall each be evidenced by a single Note payable to
the order of such Bank for the account of its  Applicable  Lending  Office in an
amount equal to the aggregate  unpaid  principal amount of such Bank's Tranche A
Loans,  Tranche B Loans and Tranche C Loans,  as the case may be. Each reference
in this  Agreement  to the  "Notes"  of a Bank  shall be  deemed to refer to and
include any or all of the Notes of such Bank  described in this Section,  as the
context may require.




                                       22

<PAGE>



          (b) Each Bank may, by notice to the  Borrower  and the  Administrative
Agent,  request that its Tranche A Loans, Tranche B Loans and Tranche C Loans of
a  particular  Type be  evidenced  by a separate  Note in an amount equal to the
aggregate  unpaid  principal  amount of such  Loans.  Each such Note shall be in
substantially  the form of Exhibit A hereto with  appropriate  modifications  to
reflect the fact that it evidences solely Loans of the relevant Type.

          (c) Upon receipt of each Bank's Notes pursuant to Section 3.01(a), the
Documentation  Agent  shall  forward  such Notes to such  Bank.  Each Bank shall
record the date, amount and Type of each Loan made by it and the date and amount
of each payment of principal  made by the Borrower  with respect  thereto on the
appropriate  Note,  and may,  if such  Bank so  elects  in  connection  with any
transfer or enforcement of any of its Notes,  endorse on the schedule  forming a
part thereof  appropriate  notations to evidence the foregoing  information with
respect to each Loan then outstanding  thereunder;  provided that the failure of
any Bank to make any such  recordation  or  endorsement  shall  not  affect  the
obligations  of the Borrower  hereunder or under the Notes.  Each Bank is hereby
irrevocably  authorized by the Borrower so to endorse its Notes and to attach to
and make a part of its Notes a  continuation  of any such  schedule  as and when
required.

          SECTION 2.04. Maturity of Loans; Mandatory Prepayments.  (a) Any Loans
outstanding on the Maturity Date (together with accrued interest  thereon) shall
be due and payable on such date.

         (b)    In addition the Loans shall be prepaid in the following amounts:

          (i) in the event that the Borrower or any of its Subsidiaries shall at
          any time, or from time to time,  receive after the date hereof any Net
          Cash Proceeds of any Reduction Event, an amount equal to the Reduction
          Percentage  of such Net Cash  Proceeds  on the date of receipt of such
          Net Cash Proceeds; and

          (ii) on each date on which the  Borrower  is  required  to notify  the
          Administrative  Agent of the  Excess  Cash  Flow for any  fiscal  year
          pursuant  to  Section  5.02(b),  an  amount  equal  to  the  Reduction
          Percentage of Excess Cash Flow for such fiscal year.

         (c) Each  prepayment of Loans pursuant to subsection (b) above shall be
applied ratably to the respective Tranche A Loans, Tranche B Loans and Tranche C
Loans of the Banks.




                                       23

<PAGE>



         SECTION  2.05.  Interest  Rates.  (a) Each Base Rate  Loan  shall  bear
interest on the outstanding principal amount thereof, for each day from the date
such Loan is made until it becomes  due,  at a rate per annum  equal to the Base
Rate for such day. Such interest  shall be payable  quarterly in arrears on each
Quarterly  Date and, with respect to the principal  amount of any Base Rate Loan
converted to a Euro-Dollar  Loan, on each date a Base Rate Loan is so converted.
Any overdue  principal of or interest on any Base Rate Loan shall bear interest,
payable on demand,  for each day until paid at a rate per annum equal to the sum
of 2% plus the rate otherwise applicable to Base Rate Loans for such day.

          (b) Each  Euro-Dollar  Loan shall  bear  interest  on the  outstanding
principal  amount thereof,  for each day during each Interest Period  applicable
thereto, at a rate per annum equal to the sum of the Euro-Dollar Margin for such
day plus the Adjusted London Interbank  Offered Rate applicable to such Interest
Period.  Such interest shall be payable for each Interest Period on the last day
thereof and, if such Interest  Period is longer than three months,  at intervals
of three months after the first day thereof.

         The "Adjusted London Interbank Offered Rate" applicable to any Interest
Period means a rate per annum equal to the quotient obtained (rounded upward, if
necessary,  to the next higher  1/10,000 of 1%) by dividing  (i) the  applicable
London  Interbank  Offered  Rate by (ii)  1.00  minus  the  Euro-Dollar  Reserve
Percentage.

         The "London  Interbank  Offered Rate" applicable to any Interest Period
means the average (rounded upward, if necessary,  to the next higher 1/16 of 1%)
of the  respective  rates per annum at which  deposits in dollars are offered to
each of the  Reference  Banks in the London  interbank  market at  approximately
11:00 A.M.  (London time) two Euro-Dollar  Business Days before the first day of
such Interest Period in an amount approximately equal to the principal amount of
the Euro-Dollar  Loan of such Reference Bank to which such Interest Period is to
apply and for a period of time comparable to such Interest Period.

          "Euro-Dollar  Reserve  Percentage"  means for any day that  percentage
(expressed  as a decimal)  which is in effect on such day, as  prescribed by the
Board  of  Governors  of the  Federal  Reserve  System  (or any  successor)  for
determining  the maximum  reserve  requirement  for a member bank of the Federal
Reserve System in New York City with deposits  exceeding five billion dollars in
respect of  "Eurocurrency  liabilities"  (or in respect of any other category of
liabilities  which includes  deposits by reference to which the interest rate on
Euro-Dollar Loans is determined or any category of extensions of credit or other
assets which includes loans by a non-United  States office of any Bank to United





                                       24

<PAGE>


States residents).  The Adjusted London Interbank Offered Rate shall be adjusted
automatically  on and as of the effective date of any change in the  Euro-Dollar
Reserve Percentage.

          (c) Any overdue principal of or interest on any Euro-Dollar Loan shall
bear  interest,  payable on demand,  for each day until paid at a rate per annum
equal to the  higher of (i) the sum of 2% plus the  Euro-Dollar  Margin for such
day plus the quotient obtained (rounded upward, if necessary, to the next higher
1/10,000 of 1%) by dividing (x) the average  (rounded upward,  if necessary,  to
the next higher 1/16 of 1%) of the  respective  rates per annum at which one day
(or,  if such amount due remains  unpaid  more than three  Euro-Dollar  Business
Days,  then for such  other  period of time not  longer  than six  months as the
Administrative  Agent may select) deposits in dollars in an amount approximately
equal to such overdue  payment due to each of the Reference Banks are offered to
such Reference  Bank in the London  interbank  market for the applicable  period
determined  as  provided  above  by  (y)  1.00  minus  the  Euro-Dollar  Reserve
Percentage (or, if the  circumstances  described in clause (a) or (b) of Section
8.01  shall  exist,  at a rate  per  annum  equal to the sum of 2% plus the rate
applicable  to Base  Rate  Loans  for such  day) and (ii) the sum of 2% plus the
Euro-Dollar  Margin for such day plus the Adjusted London Interbank Offered Rate
applicable to such Loan at the date such payment was due.

          (d) The  Administrative  Agent  shall  determine  each  interest  rate
applicable to the Loans hereunder.  The  Administrative  Agent shall give prompt
notice to the Borrower and the  participating  Banks of each rate of interest so
determined,  and its determination thereof shall be conclusive in the absence of
manifest error.

          (e) Each  Reference  Bank  agrees to use its best  efforts  to furnish
quotations to the Administrative  Agent as contemplated by this Section.  If any
Reference Bank does not furnish a timely  quotation,  the  Administrative  Agent
shall  determine  the relevant  interest  rate on the basis of the  quotation or
quotations  furnished by the  remaining  Reference  Bank or Banks or, if none of
such  quotations is available on a timely basis,  the provisions of Section 8.01
shall apply.

         SECTION 2.06. Method of Electing Interest Rates. (a) The Loans included
in the Borrowing shall bear interest  initially at the type of rate specified by
the Borrower in the Notice of Borrowing.  Thereafter, the Borrower may from time
to time  elect to change or  continue  the type of  interest  rate borne by each
Group of Loans  (subject  in each  case to the  provisions  of  Article  8),  as
follows:

          (i) if such  Loans  are Base Rate  Loans,  the  Borrower  may elect to
         convert such Loans to Euro-Dollar Loans as of any Euro-Dollar  Business
         Day and




                                       25

<PAGE>




         (ii) if such Loans are  Euro-Dollar  Loans,  the  Borrower may elect to
         convert  such Loans to Base Rate Loans or elect to continue  such Loans
         as  Euro-Dollar  Loans for an additional  Interest  Period,  subject to
         Section  2.10  in the  case  of any  such  conversion  or  continuation
         effective  on any day  other  than the  last  day of the  then  current
         Interest Period applicable to such Loans.

Each  such  election  shall be made by  giving  irrevocable  telephonic  notice,
confirmed  immediately in writing (a "Notice of Interest Rate  Election") to the
Administrative Agent not later than 10:30 A.M. (New York City time) on the third
Euro-Dollar Business Day before the conversion or continuation  selected in such
notice is to be  effective.  A Notice of Interest  Rate  Election  may, if it so
specifies,  apply to only a portion  of the  aggregate  principal  amount of the
relevant  Group of Loans;  provided  that (i) such portion is allocated  ratably
among the Loans  comprising such Group and (ii) the portion to which such Notice
applies,  and the  remaining  portion  to  which  it does  not  apply,  are each
$5,000,000  or any larger  multiple of  $1,000,000.  In no event shall the total
number of Groups of Loans at any one time outstanding exceed ten, and each Group
of Loans  shall at all times  consist  of  Tranche A Loans,  Tranche B Loans and
Tranche C Loans of the Banks ratably in proportion to their respective Tranche A
Commitments, Tranche B Commitments and Tranche C Commitments.

         (b) Each Notice of Interest Rate Election shall specify:

          (i) the Group of Loans (or,  subject to the last  sentence  of Section
          2.02(a), portion thereof) to which such notice applies;

          (ii) the date on which the conversion or continuation selected in such
          notice is to be  effective,  which shall  comply  with the  applicable
          clause of subsection (a) above;

          (iii) if the Loans comprising such Group are to be converted,  the new
          Type of Loans and, if the Loans being  converted are to be Euro-Dollar
          Loans, the duration of the next succeeding  Interest Period applicable
          thereto; and

          (iv) if such Loans are to be  continued  as  Euro-Dollar  Loans for an
          additional  Interest Period, the duration of such additional  Interest
          Period.

Each  Interest  Period  specified in a Notice of Interest  Rate  Election  shall
comply with the  provisions of the  definition  of Interest  Period set forth in
Section 1.01.




                                       26

<PAGE>



          (c) If, upon the expiration of any Interest  Period  applicable to any
Eurodollar  Loan,  the Borrower has not given a timely  Notice of Interest  Rate
Election with respect to such Loan, the Administrative  Agent shall be deemed to
have  received a Notice of Interest Rate Election from the Borrower with respect
to such Loan requesting that such Loan be converted into a Base Rate Loan on the
last day of the Interest Period applicable to such Loan.

          (d) Upon  receipt  of a Notice  of  Interest  Rate  Election  from the
Borrower  pursuant to  subsection  (a) above or a deemed  receipt of a Notice of
Interest Rate  Election  pursuant to subsection  (c) above,  the  Administrative
Agent shall  promptly  notify each Bank of the contents  thereof and such notice
shall not thereafter be revocable by the Borrower.

          (e) An  election by the  Borrower  to change or  continue  the rate of
interest  applicable  to any Group of Loans  pursuant to this Section  shall not
constitute a "Borrowing" subject to the provisions of Section 3.02.

         SECTION 2.07.  Mandatory Termination and Reduction of Commitments.
The Commitments shall terminate on the Closing Date.

         SECTION  2.08.  Optional  Prepayments.  (a)  Subject in the case of any
Euro-Dollar  Borrowing  to Section  2.12,  the Borrower  may,  upon at least one
Domestic Business Day's notice to the Administrative  Agent, prepay any Group of
Base Rate Loans, or upon at least three Euro-Dollar Business Days' notice to the
Administrative  Agent,  prepay any Group of Euro-Dollar  Loans,  in each case in
whole  at any  time,  or from  time to  time  in  part  in  amounts  aggregating
$5,000,000 or any larger multiple of $1,000,000,  by paying the principal amount
to be prepaid  together with accrued interest thereon to the date of prepayment.
Each such optional  prepayment  shall be applied to prepay ratably the Tranche A
Loans, Tranche B Loans and Tranche C Loans of the several Banks included in such
Group.

          (b) Upon receipt of a notice of  prepayment  pursuant to this Section,
the Administrative Agent shall promptly notify each Bank of the contents thereof
and of such Bank's  ratable share of such  prepayment  and such notice shall not
thereafter be revocable by the Borrower.

         SECTION 2.09. General Provisions as to Payments. (a) The Borrower shall
make each  payment  of  principal  of,  and  interest  on, the Loans and of fees
hereunder,  not later than 12:00 Noon (New York City time) on the date when due,
in  Federal  or other  funds  immediately  available  in New York  City,  to the
Administrative   Agent  at  its  address   referred  to  in  Section  5.03.  The





                                       27

<PAGE>


Administrative  Agent will promptly distribute to each Bank its ratable share of
each such payment  received by the  Administrative  Agent for the account of the
Banks to be applied  ratably  to the  Tranche A Loans,  the  Tranche B Loans and
Tranche C Loans of the Banks.  Whenever any payment of principal of, or interest
on, the Base Rate Loans or of fees shall be due on a day which is not a Domestic
Business  Day,  the date for  payment  thereof  shall  be  extended  to the next
succeeding  Domestic  Business  Day.  Whenever any payment of  principal  of, or
interest  on,  the  Euro-Dollar  Loans  shall  be  due on a day  which  is not a
Euro-Dollar  Business Day, the date for payment thereof shall be extended to the
next succeeding  Euro-Dollar  Business Day unless such Euro-Dollar  Business Day
falls in another  calendar  month,  in which case the date for  payment  thereof
shall  be the  next  preceding  Euro-Dollar  Business  Day.  If the date for any
payment of  principal is extended by  operation  of law or  otherwise,  interest
thereon shall be payable for such extended time.

          (b) Unless the  Administrative  Agent shall have received  notice from
the  Borrower  prior  to the  date on  which  any  payment  is due to the  Banks
hereunder   that  the  Borrower  will  not  make  such  payment  in  full,   the
Administrative  Agent may assume that the Borrower has made such payment in full
to the Administrative  Agent on such date and the  Administrative  Agent may, in
reliance upon such assumption,  cause to be distributed to each Bank on such due
date an amount equal to the amount then due such Bank. If and to the extent that
the Borrower  shall not have so made such payment,  each Bank shall repay to the
Administrative  Agent  forthwith on demand such amount  distributed to such Bank
together  with  interest  thereon,  for each day from the date  such  amount  is
distributed  to such Bank  until the date such Bank  repays  such  amount to the
Administrative Agent, at the Federal Funds Rate.

         SECTION  2.10.  Funding  Losses.  If the Borrower  makes any payment of
principal  with  respect  to any  Euro-Dollar  Loan or any  Euro-Dollar  Loan is
converted (pursuant to Article 2, 6 or 8 or otherwise) on any day other than the
last  day of an  Interest  Period  applicable  thereto,  or the  last  day of an
applicable period fixed pursuant to Section 2.05(c), or if the Borrower fails to
borrow or prepay any  Euro-Dollar  Loans after notice has been given to any Bank
in accordance with Section  2.02(a),  2.04 or 2.08, the Borrower shall reimburse
each Bank within 15 days after demand for any resulting loss or expense incurred
by it (or by an  existing  or  prospective  Participant  in the  related  Loan),
including  (without  limitation) any loss incurred in obtaining,  liquidating or
employing  deposits from third  parties,  but  excluding  loss of margin for the
period  after any such  payment  or  conversion  or failure to borrow or prepay,
provided that such Bank shall have delivered to the Borrower a certificate as to
the amount of such loss or expense, which certificate shall be conclusive in the
absence of manifest error.

         SECTION 2.11.  Computation of Interest and Fees.  Interest based on the
Prime Rate and  commitment  fees  hereunder  shall be computed on the basis of a





                                       28

<PAGE>



year of 365 days (or 366 days in a leap year) and paid for the actual  number of
days elapsed  (including  the first day but excluding  the last day).  All other
interest  shall be  computed on the basis of a year of 360 days and paid for the
actual  number of days elapsed  (including  the first day but excluding the last
day).

          SECTION 2.12.  Extension of Maturity  Date. If the Borrower  wishes to
extend the Maturity Date then in effect,  the Borrower shall give written notice
to the  Administrative  Agent not less  than 13  months  nor more than 18 months
prior to the Maturity Date then in effect,  whereupon the  Administrative  Agent
shall  promptly  notify  each  Bank of  such  notice.  Each  Bank  will  use its
reasonable efforts to respond to such request in writing,  whether affirmatively
or negatively,  as it may elect in its sole discretion,  within 30 days after it
receives such notice from the Administrative  Agent. If the Administrative Agent
receives an  affirmative  response in writing  from each Bank within such 30 day
period,  the Maturity Date then in effect shall be extended for one year (but in
no event later than March 31,  2006) and the  Administrative  Agent shall notify
the Borrower (with a copy to the  Shareholder  Guarantors,  it being  understood
that the consent of the  Shareholder  Guarantors  is not  required  for any such
extension  and any  failure  to give  any  such  notice  shall  not  affect  any
Shareholder  Guarantor's  obligations  under its  Shareholder  Guaranty) and the
Banks of such extension.



                                    ARTICLE 3
                                   CONDITIONS

          SECTION  3.01.  Closing.   The  closing  hereunder  shall  occur  upon
satisfaction of the following conditions:

          (a) the Documentation  Agent shall have received all of the following,
in form and substance  satisfactory to the Documentation Agent and in sufficient
copies for each Bank:

          (i) duly  executed  Notes for the  account  of each  Bank  dated on or
          before the Closing Date complying with the provisions of Section 2.03;

          (ii) the Security and Pledge Agreement duly executed by the Borrower;

          (iii) the  articles or  certificate  of  incorporation  of each of the
          Borrower and the Shareholder  Guarantors (other than Baron Capital) as
          in effect on the Closing Date,  certified by the Secretary of State or





                                       29

<PAGE>


          equivalent  official  of the  jurisdiction  of  incorporation  of such
          Person as of a recent date and by the Secretary or Assistant Secretary
          of such Person as of the Closing  Date,  and the bylaws of such Person
          as in  effect on the  Closing  Date,  certified  by the  Secretary  or
          Assistant Secretary of such Person as of the Closing Date;

          (iv) a good standing  certificate  for the Borrower from the Secretary
          of State of its  state of  incorporation  and  each  state  where  the
          Borrower is qualified to do business as a foreign  corporation as of a
          recent  date,  together  with a  bring-down  certificate  by  telex or
          telecopy, dated the Closing Date;

          (v) copies of the  resolutions  of the board of  directors  of (x) the
          Borrower  approving  and  authorizing  the  execution,   delivery  and
          performance  by the  Borrower  of this  Agreement  and the other  Loan
          Documents to be delivered by it and  authorizing  the borrowing of the
          Loans,  certified  as of  the  Closing  Date  by the  Secretary  or an
          Assistant  Secretary of the Borrower,  and (y) each of the Shareholder
          Guarantors  (other than Baron Capital)  approving and  authorizing the
          execution,  delivery  and  performance  by  such  Person  of all  Loan
          Documents to be  delivered by it,  certified as of the Closing Date by
          the Secretary or an Assistant Secretary of such Person;

          (vi) a certificate of the Secretary or an Assistant  Secretary of each
          of the  Borrower  and each  Shareholder  Guarantor  (other  than Baron
          Capital)  certifying  the names and true  signatures  of its  officers
          authorized to execute,  deliver and perform,  as applicable,  all Loan
          Documents to be delivered by it hereunder;

          (vii) a certificate  signed by a Responsible  Officer of the Borrower,
          dated as of the Closing Date,  stating that each of the conditions set
          forth in Sections 3.01(b) through (e) is satisfied as of such date;

          (viii) written advice  relating to such Lien and judgment  searches as
          either  Agent  shall  have   requested  of  the  Borrower,   and  such
          termination  statements  or other  documents  as may be  necessary  to
          release any Lien in favor of any third party not  otherwise  permitted
          by Section 5.17;

          (ix) evidence (A) that all filings,  recordations,  registrations  and
          other actions necessary or, in the opinion of either Agent,  desirable
          to perfect and protect a first  priority  (except for Permitted  Liens
          arising by  operation  of law)  security  interest  in and Lien on the
          Collateral  in  favor  of the  Administrative  Agent  have  been  duly
          effected  or taken;  (B) that each Lien  created by the  Security  and





                                       30

<PAGE>


          Pledge Agreement in the Collateral  constitutes a perfected Lien on or
          in all right,  title,  estate and  interest  of the  Borrower  in such
          Collateral  prior and superior to all Liens other than Permitted Liens
          arising  by  operation  of  law;  and  (C)  that  all   necessary  and
          appropriate consents to the creation and perfection of such Liens will
          have been obtained;

          (x) an  opinion  of (w)  Randy  S.  Segal,  counsel  to the  Borrower,
          substantially in the form of Exhibit B hereto,  (x) counsel reasonably
          satisfactory to the Agents to each Shareholder Guarantor,  in form and
          substance  satisfactory to the Documentation Agent, and (y) Davis Polk
          & Wardwell,  special counsel to the Agents,  substantially in the form
          of Exhibit C hereto;

          (xi) a copy of the financial statements of the Borrower referred to in
          Section  4.10(a) and (b),  certified by a  Responsible  Officer of the
          Borrower;

          (xii)  a  Shareholder  Guaranty  duly  executed  by  each  Shareholder
          Guarantor,  the Baron Capital  Letter of Credit and the Escrow Letter;
          and

          (xiii) all documents the  Documentation  Agent may reasonably  request
          relating  to the  existence  of the  Borrower,  any of the  Borrower's
          Subsidiaries or any Shareholder Guarantor, the corporate authority for
          and the validity of this Agreement, the Notes, the Security and Pledge
          Agreement  or  the  Shareholder  Guaranties,  and  any  other  matters
          relevant  hereto,  all  in  form  and  substance  satisfactory  to the
          Documentation Agent;

          (b) all  costs,  accrued  and  unpaid  fees and  expenses  (including,
without  limitation,  upfront  fees,  participation  fees  and  legal  fees  and
expenses) to the extent then due and payable on the Closing Date by the Borrower
hereunder shall have been paid;

          (c) AMSC  Acquisition  Company and the  Borrower  shall have  received
proceeds (net of fees and interest  reserves) of not less than $140,000,000 from
the issuance of its Senior Notes,  all conditions to the Acquisition  (including
receipt  of any  approvals  of the  FCC)  shall  have  been  satisfied  and  the
Acquisition shall have been consummated;

          (d) The Borrower  shall have  entered into a Rate  Contract to fix its
interest rate  obligations  under this  Agreement for three years and shall have
prefunded its interest obligations thereunder;

          (e) the Hughes Bridge Loan  Agreement  shall have been  terminated and
all amounts payable thereunder shall have paid in full; and





                                       31

<PAGE>



          (f) the Existing Credit  Facilities shall have been terminated and all
amounts payable thereunder shall have been paid in full.

The Documentation  Agent shall promptly notify the Borrower and the Banks of the
Closing  Date,  and such notice shall be  conclusive  and binding on all parties
hereto.

         SECTION 3.02.  Borrowings. The obligation of any Bank to make a Loan on
the occasion of the  Borrowing is subject to the  satisfaction  of the following
conditions:

          (a) the fact that the Closing Date shall have  occurred on or prior to
March 31, 1998;

          (b) receipt by the  Administrative  Agent of a Notice of  Borrowing as
required by Section 2.02(a);

          (c) the fact that,  immediately  after the  Borrowing,  the  aggregate
outstanding  principal  amount of the Loans will not exceed the aggregate amount
of the Commitments;

          (d) the fact  that,  immediately  before and after the  Borrowing,  no
Default shall have occurred and be continuing; and

          (e) the fact that the  representations  and warranties of the Borrower
contained  in the  Loan  Documents  shall  be true on and as of the  date of the
Borrowing.

The Borrowing  hereunder shall be deemed to be a representation  and warranty by
the Borrower on the date of the  Borrowing as to the facts  specified in clauses
(b) through (e) of this Section.



                                    ARTICLE 4
                         REPRESENTATIONS AND WARRANTIES

         The Borrower  represents and warrants (in each case after giving effect
to the  Acquisition;  provided that for periods prior to the Effective Date, the
representations  and warranties with respect to ARDIS are made to the Borrower's
best  knowledge in reliance on the  representations  and warranties in the ARDIS
Purchase  Agreement)  that,  except as set forth in the  section (if any) of the
Disclosure Schedule corresponding to the Section heading below:




                                       32

<PAGE>



         SECTION 4.01.  Corporate  Existence and Power. Each of the Borrower and
its Principal  Subsidiaries  (a) is a  corporation  duly  incorporated,  validly
existing  and in  good  standing  under  the  laws  of the  jurisdiction  of its
incorporation;  (b) has the power and  authority  and all material  governmental
licenses,  authorizations,  consents  and  approvals  required  to  carry on its
business  as now  conducted;  (c) is duly  qualified  as a foreign  corporation,
licensed  and in good  standing  under the laws of each  jurisdiction  where its
ownership,  lease or  operation  of  property  or the  conduct  of its  business
requires such  qualification;  and (d) is in compliance with all Requirements of
Law  except,  in the case of  clauses  (c) and (d),  where the  failure to be so
qualified or in compliance  could not  reasonably be expected to have a Material
Adverse Effect.

         SECTION 4.02. Corporate Authorization; No Contravention. The execution,
delivery and  performance  by each of the Borrower and its  Subsidiaries  of any
Loan Document to which it is a party have been duly  authorized by all necessary
corporate  action  and do not and will  not:  (a)  contravene  the terms of such
Person's  certificate of incorporation,  bylaws or other organization  document;
(b) conflict with or result in any breach or  contravention  of, or the creation
of any Lien under,  any indenture,  agreement,  lease,  instrument,  Contractual
Obligation,  injunction,  order, decree or undertaking to which such Person is a
party; or (c) violate any Requirement of Law.

         SECTION 4.03. Government  Approvals.  All material Government Approvals
heretofore required to be obtained have been duly obtained, were validly issued,
are in full force and effect, are not subject to appeal and are held in the name
of, or for the  benefit  of, the  appropriate  Persons.  There is no  proceeding
pending  or, to the best  knowledge  of the  Borrower,  threatened  against  the
Borrower or any of its  Subsidiaries,  or any property of the Borrower or any of
its  Subsidiaries,  which seeks,  or may  reasonably  be  expected,  to rescind,
terminate, materially adversely modify or suspend any of the FCC Licenses. There
has not occurred any event that would make  unlikely the delivery or issuance as
anticipated  of, and when and as needed all such Government  Approvals.  No such
Government  Approval already obtained is subject to any restriction,  condition,
limitation or other  provision that would have a Material  Adverse  Effect.  The
information  set forth in each  application  submitted by the Borrower or any of
its  Subsidiaries in connection  with each such Government  Approval is accurate
and complete in all material respects taken as a whole, except for statements or
omissions  which  could not  reasonably  be  expected  to affect  adversely  the
validity of such Government  Approvals.  No other material consent,  approval or
authorization of, or declaration or filing with, any other Person is required in
connection with the execution, delivery, performance, validity or enforceability
of this Agreement or any other Loan Document.




                                       33

<PAGE>



         SECTION  4.04.  Binding  Effect.  This  Agreement  and each  other Loan
Document to which the Borrower or any of its  Subsidiaries is a party constitute
the legal,  valid and binding  obligations of such Person,  enforceable  against
such Person in accordance with their respective terms,  except as enforceability
may be limited by applicable bankruptcy,  insolvency,  or similar laws affecting
the  enforcement  of  creditors'  rights  generally or by  equitable  principles
relating to enforceability.

         SECTION  4.05.  Litigation.   Except  for  matters  arising  after  the
Effective Date which could not reasonably be expected to have a Material Adverse
Effect, there are no actions, suits, proceedings, claims or disputes pending, or
to the best  knowledge of the Borrower,  threatened or  contemplated  at law, in
equity,  in  arbitration  or before  any  Governmental  Authority,  against  the
Borrower or any of its Subsidiaries or any of their respective properties which:
(a) purport to affect or pertain to this Agreement, or any Loan Document, or any
of the  transactions  contemplated  hereby  or  thereby;  or  (b) if  determined
adversely  to the  Borrower  or any of its  Subsidiaries,  could have a Material
Adverse Effect. No injunction, writ, temporary restraining order or any order of
any  nature  has  been  issued  by any  court or  other  Governmental  Authority
purporting to enjoin or restrain the execution, delivery and performance of this
Agreement  or any  other  Loan  Document,  or  directing  that the  transactions
provided for herein or therein not be consummated as herein or therein provided.

         SECTION  4.06.  No  Default.  No Default or Event of Default  exists or
would  result from the  incurring of  Obligations  by the Borrower or any of its
Subsidiaries  under  any Loan  Document.  Neither  the  Borrower  nor any of its
Subsidiaries is in default under or with respect to any  Contractual  Obligation
in any respect which,  individually  or together with all such  defaults,  could
have a Material Adverse Effect.

         SECTION  4.07.  ERISA  Compliance.  (a) Section 4.07 of the  Disclosure
Schedule  lists all Plans  maintained  or  sponsored by the Borrower or to which
either of them is obligated  to  contribute,  and  separately  identifies  Plans
intended to be Qualified Plans and Multiemployer Plans. All written descriptions
thereof  provided to the Agents are true and complete in all material  respects.
Each  Plan  is in  compliance  in all  material  respects  with  the  applicable
provisions  of ERISA,  the Code and other  Federal or state law,  including  all
requirements  under the Code or ERISA for  filing  reports  (which  are true and
correct in all material  respects as of the date filed),  and benefits have been
paid in accordance with the provisions of the Plan. Each Qualified Plan has been
determined by the IRS to qualify under Section 401 of the Code,  and to the best
knowledge  of the Borrower  nothing has  occurred  which would cause the loss of
such qualification.




                                       34

<PAGE>



          (b) There is no  outstanding  liability  under  Title IV of ERISA with
respect to any Plan  maintained  or  sponsored  by any member of the  Controlled
Group (as to which the  Borrower is or may be liable),  nor with  respect to any
Plan to which any member of the Controlled Group  contributes or is obligated to
contribute  (wherein the Borrower is or may be liable).  No Plan  maintained  or
sponsored by the Borrower  provides medical or other welfare benefits or extends
coverage   relating  to  such  benefits  beyond  the  date  of  a  participant's
termination of employment  with the Borrower,  except to the extent  required by
Section  4980B of the Code and at the sole  expense  of the  participant  or the
beneficiary  of the  participant to the fullest  extent  permissible  under such
Section of the Code. The Borrower has complied in all material respects with the
notice and continuation coverage requirements of Section 4980B of the Code.

          (c) No ERISA  Event has  occurred or is  reasonably  expected to occur
with respect to any Plan maintained or sponsored by the Borrower or to which the
Borrower  is  obligated  to  contribute.  There are no  pending  or, to the best
knowledge of the Borrower,  threatened claims,  actions or lawsuits,  other than
routine  claims for  benefits  in the usual and  ordinary  course,  asserted  or
instituted  against (i) any Plan  maintained or sponsored by the Borrower or its
assets,  (ii) any member of the  Controlled  Group with respect to any Qualified
Plan of the Borrower,  or (iii) any fiduciary with respect to any Plan for which
the  Borrower  may be directly or  indirectly  liable,  through  indemnification
obligations or otherwise.  The Borrower has not incurred and does not reasonably
expect to incur (i) any  liability  (and no event has occurred  which,  with the
giving of notice under  Section 4219 of ERISA,  would result in such  liability)
under  Section  4201 of ERISA with respect to a  Multiemployer  Plan or (ii) any
liability  under Title IV of ERISA (other than  premiums due and not  delinquent
under  Section  4007 of ERISA)  with  respect to a Plan.  The  Borrower  has not
transferred any Unfunded  Pension  Liability  outside of the Controlled Group or
otherwise  engaged in a  transaction  that  could be subject to Section  4069 or
4212(c) of ERISA.

          (d) The  Borrower  has  not  engaged,  directly  or  indirectly,  in a
non-exempt  prohibited  transaction  (as defined in Section  4975 of the Code or
Section 406 of ERISA) in connection with any Plan, which  transaction could have
a Material Adverse Effect.

         SECTION  4.08.  Title  to  Property.  Each  of  the  Borrower  and  its
Subsidiaries  has good  record  and  marketable  title in fee simple to or valid
leasehold  interests in all real property used in its business,  except for such
defects in title as could not, individually or in the aggregate, have a Material
Adverse  Effect.  Such real property is free and clear of all Liens or rights of
others, except Permitted Liens.




                                       35

<PAGE>



         SECTION  4.09.  Taxes.  Each of the Borrower and its  Subsidiaries  has
filed all Federal  and other  material  tax  returns and reports  required to be
filed and have paid all Federal and other material taxes, assessments,  fees and
other  governmental  charges  levied or imposed  upon them or their  properties,
income  or  assets  otherwise  due and  payable  except  those  which  are being
contested  in good  faith by  appropriate  proceedings  and for  which  adequate
reserves have been  provided in  accordance  with GAAP and no Notice of Lien has
been filed or recorded. There is no proposed tax assessment against the Borrower
or any of its  Subsidiaries  which would,  if the assessment  were made,  have a
Material Adverse Effect.

         SECTION 4.10.  Financial Condition.

          (a) The audited  consolidated  statements of financial position of the
Borrower  and  its  Subsidiaries  dated  December  31,  1996,  and  the  related
consolidated  statements  of loss,  stockholders'  equity and cash flows for the
fiscal  year ended on that  date:  (i) were  prepared  in  accordance  with GAAP
consistently applied throughout the periods covered thereby, except as otherwise
expressly noted therein,  (ii) fairly  present,  in all material  respects,  the
financial  condition of the Borrower and its Subsidiaries as of the date thereof
and  results of  operations  for the period  covered  thereby and (iii) show all
material  Indebtedness  and  other  liabilities,  direct or  contingent,  of the
Borrower and its  consolidated  Subsidiaries  as of the date thereof  (including
liabilities for taxes and material commitments).

          (b) The  unaudited pro forma summary  consolidated  condensed  balance
sheet of the Borrower and its  Subsidiaries  as of September  30, 1997  together
with the related pro forma summary  condensed  statement of operations  data for
the nine months then ended fairly present,  in conformity with GAAP applied on a
basis  consistent  with the financial  statements  referred to in subsection (a)
above, the consolidated  financial position of the Borrower and its Subsidiaries
as of such date, based on the assumptions set forth therein. As of such date and
the Closing  Date,  the Borrower and its  Subsidiaries  had and have no material
liabilities,  contingent or otherwise,  which are not properly reflected on such
balance sheet (including liabilities for taxes and material commitments).

          (c) Since  September  30,  1997,  there has been no  Material  Adverse
Effect.

         SECTION 4.11. Environmental Matters. The operations of the Borrower and
each of its Subsidiaries  comply in all material respects with all Environmental
Laws.  The Borrower and each of its  Subsidiaries  have  obtained all  licenses,
permits,  authorizations and registrations  required under any Environmental Law
("Environmental Permits") necessary for its operations to comply in all material




                                       36

<PAGE>



respects with Environmental Laws, and all such Environmental Permits are in full
force and effect,  and the Borrower and each of its Subsidiaries are in material
compliance with all terms and conditions of such Environmental  Permits. None of
the  Borrower,  any of its  Subsidiaries  or any of  their  present  or,  to the
knowledge  of the  Borrower,  past  property  or  operations  is  subject to any
outstanding  written order from or agreement with any Governmental  Authority or
other  Person,  nor  subject  to  any  judicial  or  administrative  proceeding,
respecting any Environmental  Law,  Environmental  Claim or Hazardous  Material.
There  are  no  conditions  or   circumstances   which  may  give  rise  to  any
Environmental  Claim  arising  from  the  operations  of  the  Borrower  or  its
Subsidiaries,  including  Environmental Claims associated with any operations of
the  Borrower  or its  Subsidiaries,  with a  potential  liability  in excess of
$5,000,000 in the aggregate.  Without  limiting the generality of the foregoing,
the Borrower and its Subsidiaries have met all notification  requirements  under
Title III of the Superfund  Amendments  and  Reauthorization  Act of 1986 or any
other Environmental Law.

         SECTION 4.12.  Regulated  Entities.  None of the  Borrower,  any Person
controlling  the Borrower,  or any  Subsidiary  thereof,  is (a) an  "Investment
Company"  within  the  meaning of the  Investment  Company  Act of 1940;  or (b)
subject to regulation  under the Public Utility Holding Company Act of 1935, the
Federal Power Act, the Interstate  Commerce Act, any state public utilities code
or any other  Federal or state  statute or  regulation  limiting  its ability to
incur Indebtedness.

         SECTION 4.13.  Subsidiaries.  As of the Closing Date, the Borrower does
not have any Subsidiaries and has no equity investments in any other corporation
or entity.

         SECTION  4.14.  Insurance.  The  properties  of the  Borrower  and  its
Subsidiaries  are  insured  with  financially  sound  and  reputable   insurance
companies,  in such amounts, with such deductibles and covering such risks as is
customarily  carried on by companies  engaged in similar  businesses  and owning
similar properties in localities where the Borrower or such Subsidiary operates.

         SECTION  4.15.  Business.  The Borrower and its  Subsidiaries  have not
conducted  any business  other than as  described  in the  Offering  Memorandum.
Neither the business nor the properties of the Borrower and its Subsidiaries are
or have been affected by any fire, explosion, accident, strike, lockout or other
labor dispute,  drought, storm, hail, earthquake,  embargo, act of God or of the
public enemy or other casualty  (whether or not covered by insurance)  which has
had a Material Adverse Effect.

         SECTION 4.16.  Collateral; Property. All contracts and all property now
owned by the  Borrower  are held by it free and  clear of all Liens  other  than





                                       37

<PAGE>



Permitted Liens. The Borrower has good, marketable and valid title in and to all
of the  Collateral  now  owned by it,  in each  case free and clear of all Liens
other than Permitted Liens.

         SECTION 4.17.  Security and Pledge  Agreement.  The Security and Pledge
Agreement  creates  in favor of the  Administrative  Agent,  for the  equal  and
ratable (except as expressly  provided  therein) benefit of the Secured Parties,
legal,  valid and enforceable Liens on or in all of the Collateral to the extent
that such  Liens may  legally be given and be  effective  and  enforceable.  All
filings, recordations, registrations and other actions necessary to perfect such
Liens have been duly effected, and, to the extent that such Liens may legally be
given and be effective  and  enforceable,  each Lien created by the Security and
Pledge Agreement  constitutes a perfected Lien on or in all right, title, estate
and  interest  of the  Borrower in the  Collateral  covered  thereby,  prior and
superior to all other Liens except  Permitted Liens arising by operation of law,
and all necessary  and  appropriate  consents to the creation and  perfection of
such Liens have been obtained.

         SECTION  4.18.   Disclosure.   The  information   (including,   without
limitation,  the information in the Offering Memorandum) furnished in writing at
or prior to the Closing Date by the Borrower to any Agent or Bank in  connection
with this Agreement and the transactions  contemplated  hereby is true, complete
and accurate in every material  respect or based on reasonable  estimates on the
date as of which such  information  is stated or certified and is not incomplete
by omitting to state any material fact necessary to make such information (taken
as a whole)  not  misleading  in light of the  circumstances  under  which  such
information  was made.  The pro forma  financial  projections  contained  in the
Offering  Memorandum were made in good faith and the assumptions on the basis of
which such  projections  were made were  (when  made) and are (as of the date of
this Agreement)  reasonable.  There is no fact known to the Borrower on the date
as of which this representation and warranty is made that has not been disclosed
in writing to the Agent  which could  reasonably  be expected to have a Material
Adverse Effect.



                                    ARTICLE 5
                                    COVENANTS

         The  Borrower  agrees  that,  so long as any  Bank  has any  Commitment
hereunder or any amount payable hereunder or under any Note remains unpaid:

         SECTION  5.01.  Information.  The Borrower will deliver to each of the
Banks:




                                       38

<PAGE>



          (a) as soon as available,  but not later than 90 days after the end of
each  fiscal  year of the  Borrower,  commencing  with the  fiscal  year  ending
December  31,  1997, a copy of the audited  consolidated  balance  sheets of the
Borrower  as at the  end of  such  year  and the  related  audited  consolidated
statements of income,  stockholders' equity and cash flows for such fiscal year,
setting  forth in each case in  comparative  form the figures  for the  previous
year,  and  accompanied  by the  opinion  of  Arthur  Andersen  LLP  or  another
nationally-recognized  independent  public  accounting  firm which  report shall
state  that  such  consolidated  financial  statements  present  fairly,  in all
material respects, the financial position,  results of operations and cash flows
for the periods  indicated in conformity with GAAP applied on a basis consistent
with prior years;

          (b) as soon as available,  but not later than 45 days after the end of
each of the first three fiscal quarters of each year,  commencing with the first
such fiscal  quarter to end after the  Effective  Date, a copy of the  unaudited
consolidated  balance  sheets of the  Borrower as of the end of such quarter and
the related  consolidated  statements of income,  stockholders'  equity and cash
flows for the period  commencing  on the first day and ending on the last day of
such quarter,  and  certified by an  appropriate  Responsible  Officer as fairly
presenting,  in all material  respects,  in accordance with GAAP (except for the
absence of  footnote  disclosure),  the  financial  position  and the results of
operations of the Borrower; and

          (c) as soon as available,  any other interim  financial  statements of
the Borrower and its  Subsidiaries  reasonably  requested by the  Administrative
Agent at the direction of the Required Banks.

         SECTION  5.02.   Certificates;  Other  Information.  The Borrower  will
deliver to each of the Banks:

          (a)  concurrently  with  the  delivery  of  the  financial  statements
referred to in Section 5.01(a) above, a certificate of the independent certified
public accountants reporting on such financial statements stating that in making
the examination  necessary  therefor no knowledge was obtained of any Default or
Event of Default, except as specified in such certificate;

          (b)  concurrently  with  the  delivery  of  the  financial  statements
referred to in Section 5.01(a) above, a certificate of a Responsible  Officer of
the Borrower (i) stating  that,  to the best of such  officer's  knowledge,  the
Borrower, during such period, has observed or performed all of its covenants and
other agreements,  and satisfied every condition  contained in this Agreement to
be observed, performed or satisfied by it, and that such officer has obtained no
knowledge  of any  Default  or Event of  Default  except  as  specified  in such





                                       39

<PAGE>


certificate, (ii) when applicable, showing in detail the calculations supporting
such  statement in respect of Article 5 and (iii)  setting forth the Excess Cash
Flow for such  period,  together  with the  calculation  thereof  in  reasonable
detail;

          (c) promptly  after the same are filed,  copies of (if, in the case of
reports to the FCC,  such reports are material)  all  financial  statements  and
regular,  periodical or special  reports which the Borrower or any Subsidiary of
the Borrower may make to, or file with, the Securities and Exchange  Commission,
the FCC or any successor or similar Governmental Authorities; and

          (d) promptly,  such additional  financial and other information as the
Administrative  Agent,  at the  request  of any  Bank,  may  from  time  to time
reasonably request.

          SECTION 5.03.  Notices.  The Borrower shall promptly notify the Agents
and each Bank of:

          (a) the  occurrence  of any  Default or Event of  Default,  and of the
occurrence or existence of any event or  circumstance  that could  reasonably be
expected to become a Default or Event of Default;

          (b) any (i) breach or  non-performance  of, or any  default  under any
Contractual  Obligation  which  could  reasonably  be  expected  to  result in a
Material Adverse Effect; or (ii) dispute, litigation, investigation,  proceeding
or  suspension  which may exist at any time  between the  Borrower or any of its
Subsidiaries and any Governmental  Authority and which, if determined  adversely
to the  Borrower or any of its  Subsidiaries,  could  reasonably  be expected to
result in a Material Adverse Effect;

          (c)  the  commencement  of,  or  any  material   development  in,  any
litigation or proceeding  affecting the Borrower or any  Subsidiary (i) in which
the  amount of damages  claimed  is  $5,000,000  (or its  equivalent  in another
currency or currencies) or more,  (ii) in which  injunctive or similar relief is
sought and which, if adversely determined, could have a Material Adverse Effect,
or (iii) in which  the  relief  sought  is an  injunction  or other  stay of the
performance of any Loan Document or the operations of the Borrower or any of its
Subsidiaries;

          (d) upon, but in no event later than ten days after, becoming aware of
(i)  any  and  all  enforcement,  cleanup,  removal  or  other  governmental  or
regulatory actions  instituted,  completed or threatened against the Borrower or
any  Subsidiary  or  any  of  their   properties   pursuant  to  any  applicable
Environmental   Laws,  (ii)  all  other   Environmental   Claims  or  (iii)  any
environmental  or similar  condition  on any real  property  adjoining or in the





                                       40

<PAGE>


vicinity of the property of the Borrower or any of its  Subsidiaries  that could
reasonably  be  anticipated  to cause such  property  or any part  thereof to be
subject to any restrictions on the ownership, occupancy,  transferability or use
of such property under any Environmental Laws;

          (e) any other  litigation or proceeding  affecting the Borrower or any
of its  Subsidiaries  which  the  Borrower  would be  required  to report to the
Securities and Exchange  Commission  pursuant to the Securities  Exchange Act of
1934,  within four days after  reporting the same to the Securities and Exchange
Commission;

          (f) any  ERISA  Event  affecting  the  Borrower  or any  member of its
Controlled  Group (but in no event  more than ten days  after such ERISA  Event)
together  with (i) a copy of any notice  with  respect to such ERISA Event filed
with the PBGC and (ii) any notice  delivered  by the PBGC to the Borrower or any
member or its Controlled Group with respect to such ERISA Event;

          (g) any Material  Adverse  Effect  subsequent  to the date of the most
recent  audited  financial  statements  of the  Borrower  delivered to the Banks
pursuant to Section 5.01(a);

          (h) any material change in accounting  policies or financial reporting
practices;

          (i) any labor controversy resulting in or threatening to result in any
strike,  work stoppage,  boycott,  shutdown or other labor disruption against or
involving the Borrower or any Subsidiary;

          (j)   any material revision of the Borrower's business plan;

          (k) the adoption of each capital expenditures budget by the Borrower;

          (l) any event that could  reasonably be expected to result in Net Cash
Proceeds requiring a mandatory prepayment pursuant to Section 2.04; and

          (m) the  delivery  of, or receipt of, any notice of (i) a reduction in
coverage of any insurance required to be maintained by Section 5.06 or otherwise
procured by the Borrower covering loss or damage to any material property of the
Borrower (other than a reduction in coverage or amount  resulting from a payment
thereunder)  or (ii) the  cancellation  or  non-renewal  of any  such  insurance
policy.

Each  notice  pursuant  to this  Section  shall be  delivered  promptly  after a
Responsible Officer becomes aware of the subject matter of such notice and shall
be accompanied by a written  statement by a Responsible  Officer of the Borrower





                                       41

<PAGE>


setting forth details and effective date of the  occurrence  referred to therein
and stating what action the Borrower proposes to take with respect thereto.

         SECTION 5.04. Conduct of Business; Preservation of Corporate Existence.
The Borrower shall, and shall cause each of its  Subsidiaries:  (a) to engage in
business of the same  general  type as now  conducted  by the  Borrower  and its
Subsidiaries  (including  ARDIS  and  AMRC  Holdings  and  Subsidiaries  of AMRC
Holdings);  (b) to preserve and maintain in full force and effect its  corporate
existence  and good  standing  under  the laws of its State or  jurisdiction  of
incorporation; (c) to preserve and maintain in full force and effect all rights,
privileges,  qualifications,  permits,  licenses  and  franchises  necessary  or
desirable  in the normal  conduct  of its  business;  (d) to use its  reasonable
efforts,  in the ordinary course and consistent with past practice,  to preserve
its  business  organization  and  preserve  the  goodwill  and  business  of the
customers,  suppliers and others having  business  relations with it; and (e) to
preserve  or renew all of its  registered  trademarks,  trade  names and service
marks, the non-preservation of which could have a Material Adverse Effect.

         SECTION 5.05. Maintenance of Property. The Borrower shall maintain, and
shall cause each of its Principal  Subsidiaries and Subsidiaries,  respectively,
to  maintain,  and  preserve  all its  property  which is used or  useful in its
business in good working order and condition, ordinary wear and tear excepted.

         SECTION 5.06.  Maintenance of Insurance.  The Borrower shall, and shall
cause each of its  Subsidiaries  (other than AMRC Holdings and  Subsidiaries  of
AMRC  Holdings) to,  maintain in full force and effect at all times on and after
the  Effective  Date property  insurance  with  financially  sound and reputable
insurance  companies,  in such amounts,  with such deductibles and covering such
risks as is customarily  carried by companies engaged in similar  businesses and
owning similar  properties in localities  where the Borrower or such  Subsidiary
operates:

         SECTION 5.07.  Payment of Obligations.  The Borrower  shall,  and shall
cause each of its Principal Subsidiaries and Subsidiaries, respectively, to, pay
and discharge as the same shall become due and payable,  all its obligations and
liabilities,  including:  (a) all tax liabilities,  assessments and governmental
charges or levies upon it or its properties or assets, unless the same are being
contested in good faith by  appropriate  proceedings  and  adequate  reserves in
accordance with GAAP are being maintained by such Person;  (b) all lawful claims
which, if unpaid, might by law become a Lien upon its property (excluding claims
being contested in good faith by the Borrower,  and for which adequate  reserves
have been made or as to which the corresponding liens have been bonded); and (c)





                                       42

<PAGE>


all  Indebtedness  as and when due and payable but subject to any  subordination
provisions   contained  in  any   instrument   or  agreement   evidencing   such
Indebtedness.

         SECTION 5.08.  Compliance  with Laws.  The Borrower  shall comply,  and
shall cause each of its  Subsidiaries to comply,  in all material  respects with
all Requirements of Law of any Governmental  Authority having  jurisdiction over
it or its business  (including the Federal Fair Labor  Standards Act and ERISA),
except such as may be contested in good faith or as to which a bona fide dispute
may exist.

         SECTION  5.09.  Inspection  of  Property  and  Books and  Records.  The
Borrower shall maintain, and shall cause each of its Subsidiaries, respectively,
to maintain, proper books of record and account, in which full, true and correct
entries  in  conformity  with  GAAP  consistently  applied  shall be made of all
financial  transactions  and matters  involving  the assets and  business of the
Borrower and such Subsidiaries. The Borrower will permit, and will cause each of
its  Subsidiaries to permit,  representatives  of any Agent or Bank to visit and
inspect any of its properties, to examine its corporate, financial and operating
records  and make  copies  thereof or  abstracts  therefrom,  and to discuss its
affairs,  finances and accounts  with its  directors,  officers,  employees  and
independent  public  accountants at such reasonable times during normal business
hours and as often as may be reasonably desired,  upon reasonable advance notice
to the Borrower;  provided that when an Event of Default exists  representatives
from the United States offices of any Agent or Bank may visit and inspect at the
expense of the Borrower such  properties at any time during  business  hours and
without  advance  notice.  The Borrower shall reimburse the Agents and the Banks
for  their   reasonable   expenses   incurred  in  conducting  such  visits  and
examinations when an Event of Default exists.

         SECTION 5.10.  Environmental Laws.  (a) The  Borrower shall,  and shall
cause each of its  Subsidiaries to, conduct its operations and keep and maintain
its property in compliance with all Environmental Laws.

          (b) Upon  written  request of any Agent or Bank,  the  Borrower  shall
submit and cause each of its  Subsidiaries to submit,  to such Agent or Bank, at
the Borrower's sole cost and expense at reasonable intervals, a report providing
an update of the status of and any  environmental,  health or safety  compliance
obligation, remedial obligation or liability, that could, individually or in the
aggregate, result in liability in excess of $5,000,000.

         SECTION 5.11.  Use of Proceeds.  The Borrower shall use the proceeds of
the Loans only to refinance  obligations  under the Hughes Bridge Loan Agreement
and the  Existing  Credit  Facilities.  No  portion  of the Loans  will be used,





                                       43

<PAGE>


directly or  indirectly,  for the  purpose,  whether  immediate,  incidental  or
ultimate,  of buying or  carrying  any  "margin  stock"  within  the  meaning of
Regulation  U. No proceeds of any Loans will be used to acquire any  security in
any transaction which is subject to Section 13 or 14 of the Securities  Exchange
Act of 1934, as amended.

         SECTION 5.12. Security and Pledge Agreement.  The Borrower shall at all
times ensure that (i) the Security and Pledge Agreement  creates in favor of the
Administrative  Agent, for the equal and ratable benefit of the Secured Parties,
legal, valid and enforceable Liens on or in all Collateral covered thereby; (ii)
all  filings,  recordations,   registrations  and  other  actions  necessary  or
desirable  to  perfect  the Liens  created  or  purported  to be  created by the
Security and Pledge  Agreement have been duly effected;  (iii) each Lien created
by the Security and Pledge  Agreement  constitutes a perfected Lien on or in all
right,  title,  estate and  interest  of the  Borrower,  as  applicable,  in the
Collateral,  prior and superior to all Liens other than Permitted  Liens arising
by operation  of law; and (iv) all  necessary  and  appropriate  consents to the
creation and  perfection  of the Liens created or purported to be created by the
Security and Pledge Agreement have been obtained.

         SECTION  5.13.   No  Subsidiaries.  The  Borrower  shall  not  have any
Subsidiaries or equity  investments in any other corporation or entity except as
set forth on Schedule 4.13.

         SECTION 5.14. FCC Approval. The Borrower shall take any action that the
Administrative Agent may reasonably request in order to obtain from the FCC such
approval (other than relief from the FCC's alien ownership  restrictions) as may
be necessary to enable the  Administrative  Agent to exercise and enjoy the full
rights and  benefits  granted to the  Administrative  Agent by the  Security and
Pledge Agreement and each other agreement,  instrument and document delivered to
the Administrative  Agent in connection  therewith.  The Borrower shall, without
limitation,  also use diligent efforts,  at the expense of the Borrower,  (a) to
assist the Administrative  Agent in obtaining approval of the FCC for any action
or  transaction  contemplated  by the  Borrower's  business plan included in the
Offering  Memorandum for which such approval is or shall be required by law, and
(b) upon request of the Administrative Agent, to prepare, sign and file with the
FCC the assignor's or  transferor's  portion of any  application or applications
for consent to the assignment of any license or transfer or control necessary or
appropriate  under the FCC's rules and  regulations  for approval of any sale or
sales of any Collateral or any assumption by the Administrative  Agent of voting
rights  relating  thereto  effected in accordance with the terms of the Security
and Pledge Agreement.

         SECTION 5.15.   Government  Approvals.  The Borrower  shall,  and shall
cause each of its Subsidiaries to, comply with the terms of and maintain in full





                                       44

<PAGE>


force and effect the FCC Licenses,  and all amendments  thereto,  and shall, and
shall cause each of its  Subsidiaries  to, obtain,  maintain and comply with the
terms of all other  Government  Approvals which are necessary  under  applicable
laws and  regulations  in connection  with the  Borrower's or such  Subsidiary's
business.  No such  Government  Approval  shall be subject  to any  restriction,
condition,  limitation  or other  provision  that would have a Material  Adverse
Effect.

         SECTION 5.16.  Further Assurances.

          (a) The Borrower shall ensure that all written  information,  exhibits
and  reports  furnished  to the  Banks do not and will not  contain  any  untrue
statement of a material  fact and do not and will not omit to state any material
fact or any  fact  necessary  to  make  the  statements  contained  therein  not
misleading  in  light of the  circumstances  in which  made,  and will  promptly
disclose to the Agents and the Banks and correct any defect or error that may be
discovered therein or in any Loan Document or in the execution,  acknowledgement
or recordation thereof.

          (b) Promptly upon written request by the  Administrative  Agent or the
Required Banks,  the Borrower shall (and shall cause any of its Subsidiaries to)
do, execute,  acknowledge,  deliver, record, re-record,  file, re-file, register
and re-register,  any and all such further acts,  deeds,  conveyances,  security
agreements, mortgages, assignments, estoppel certificates,  financing statements
and  continuations  thereof,  termination  statements,  notices  of  assignment,
transfers, certificates,  assurances and other instruments as the Administrative
Agent or such  Banks may  reasonably  require  from time to time in order (i) to
carry out more  effectively  the  purposes of this  Agreement  or any other Loan
Document,  (ii) to  subject  to the Liens  created  by the  Security  and Pledge
Agreement any of the properties,  rights or interests covered thereby,  (iii) to
perfect and maintain the  validity,  effectiveness  and priority of the Security
and Pledge Agreement and the Liens intended to be created  thereby,  and (iv) to
better assure, convey, grant, assign, transfer, preserve, protect and confirm to
the  Administrative  Agent and  Banks the  rights  granted  or now or  hereafter
intended to be granted to the Banks  under any Loan  Document or under any other
instrument executed in connection therewith.

         SECTION 5.17.  Limitation on Liens.  The Borrower  shall not, and shall
not permit any other member of the Borrower  Group to,  directly or  indirectly,
make, create,  incur, assume or suffer to exist any Lien upon or with respect to
any part of its property or assets,  whether now owned or hereafter acquired, or
offer or agree to do so, other than the following ("Permitted Liens"):




                                       45

<PAGE>



          (a) any Lien  existing on the  Effective  Date  securing  Indebtedness
existing on the Effective Date and identified on Schedule 5.17;

          (b) any Lien in favor of the  Administrative  Agent  created under any
Loan Document and any Lien in favor of the  Shareholder  Guarantors  pursuant to
the Shareholder Guarantor Security Agreement;

          (c) Liens for taxes, fees,  assessments or other governmental  charges
which are not delinquent or remain  payable  without  penalty,  or to the extent
that non-payment  thereof is permitted by Section 5.07,  provided that no Notice
of Lien has been filed or recorded;

          (d) carriers', warehousemen's,  mechanics', landlords', materialmen's,
repairmen's  or other similar  Liens arising in the ordinary  course of business
which do not  secure  Indebtedness  and are not  delinquent  or  remain  payable
without penalty;

          (e) Liens  (other than any Lien  imposed by ERISA) on the  property of
any member of the Borrower Group incurred,  or pledges or deposits required,  in
connection with workmen's compensation,  unemployment insurance and other social
security legislation;

          (f) Liens on the property of any member of the Borrower Group securing
(i) the performance of bids,  trade contracts  (other than for borrowed  money),
leases, statutory obligations,  and (ii) obligations on surety and appeal bonds,
and (iii) other  obligations of a like nature incurred in the ordinary course of
business which do not secure  Indebtedness,  provided that all such Liens in the
aggregate could not cause a Material Adverse Effect;

          (g)   easements,   rights-of-way,   restrictions   and  other  similar
encumbrances  incurred  in  the  ordinary  course  of  business  which,  in  the
aggregate,  are  not  substantial  in  amount,  and  which  do not  in any  case
materially  detract from the value of the property  subject thereto or interfere
with the ordinary conduct of the businesses of the Borrower Group;

          (h)  Liens  on any  asset  which is the  subject  of a  capital  lease
securing  Indebtedness  incurred or assumed for the purpose of financing  all or
any  part of the cost of  acquiring  such  asset,  provided  that (x) such  Lien
attaches  concurrently with or within 30 days after the acquisition thereof, and
(y) the sum of the aggregate  principal amount of such  Indebtedness  secured by
such Liens shall not exceed $15,000,000;





                                       46

<PAGE>



          (i) Liens on contract rights under  subscriber  equipment leases sold,
pledged or  otherwise  transferred  pursuant to any bona fide  financing of such
leases;

          (j)  Liens  on  property   and  assets  of  AMRC   Holdings   and  its
Subsidiaries; and

          (k) Liens to secure Vendor Financing Indebtedness permitted by Section
5.25(k) provided that such Liens cover only the assets acquired with such Vendor
Financing Indebtedness.

         SECTION 5.18.  Disposition of Assets,  Consolidations and Mergers.  The
Borrower  shall  not,  and shall not  permit  any  Subsidiary  (other  than AMRC
Holdings and  Subsidiaries  of AMRC Holdings) to,  directly or  indirectly,  (i)
sell, assign, lease, convey, transfer or otherwise dispose of (whether in one or
a series of  transactions)  any of its assets,  business or property  (including
accounts  and  notes  receivable  (with  or  without   recourse)  and  equipment
sale-leaseback transactions) or (ii) merge or consolidate with any other Person,
or enter into any agreement to do any of the foregoing  described in clauses (i)
or (ii) except for the following;  provided that immediately after giving effect
to any of the following, no Default or Event of Default would exist:

          (a) sales,  transfers,  or other  dispositions of inventory,  or used,
worn-out or surplus property,  or property of no further use to the Borrower and
its Subsidiaries, all in the ordinary course of business;

          (b)  sales,  transfers,  or other  dispositions  of  equipment  in the
ordinary  course of business to the extent that such  equipment is exchanged for
credit  against  the  purchase  price of similar  replacement  equipment  or the
proceeds of such sale are reasonably  promptly  applied to the purchase price of
such replacement equipment;

          (c)  sales,   transfers,   or  other  dispositions  of  communications
services, capacity or equipment pursuant to the customer contracts providing for
the sale of  communications  services,  capacity or  equipment  in the  ordinary
course of business;

          (d)  sales,  transfers  or other  dispositions  pursuant  to bona fide
sale-leaseback  financings in which the lease gives rise solely to Capital Lease
Obligations;  provided,  however,  that  any  such  sales,  transfers  or  other
dispositions are not permitted with any assets of the communications network;

          (e) sales,  transfers, or other dispositions of assets in the ordinary
course of business having a fair market value not exceeding $500,000 per item or





                                       47

<PAGE>


$1,000,000 in the aggregate in any fiscal year (excluding  sales,  transfers and
dispositions  theretofore  approved in accordance  with the terms hereof in such
fiscal year);

          (f)  sales,  transfers  or  other  dispositions  of  assets  to  Sales
Corporation to be used in connection with the sales and marketing of services of
AMSC Acquisition Company and having a fair market value not exceeding $5,000,000
in the aggregate during the term of this Agreement;

          (g) sales,  transfers or other  dispositions  of contract rights under
subscriber equipment leases pursuant to any bona fide financing of such leases;

          (h) non-exclusive licenses of technology and other intangible assets;

          (i) sales of mobile earth terminals and related  equipment,  and other
inventory;

          (j) any  Subsidiary of the Borrower may merge,  consolidate or combine
with or into, or transfer assets to the Borrower or one or more  Subsidiaries of
the Borrower;  provided that with respect to any such transaction  involving the
Borrower,  the Borrower shall be the continuing or surviving  corporation and if
any  such  transaction   shall  be  between  a  Subsidiary  and  a  wholly-owned
Subsidiary,  the  wholly-owned  Subsidiary  shall be the continuing or surviving
corporation;

          (k) any  Subsidiary  of the  Borrower  may sell,  lease,  transfer  or
otherwise  dispose of any or all of its assets (upon  voluntary  liquidation  or
otherwise), to the Borrower or another wholly-owned Subsidiary of the Borrower;

          (l) the Borrower or any Subsidiary  may merge,  consolidate or combine
with another  entity if the  Borrower or the  Subsidiary,  respectively,  is the
corporation surviving the merger; and

          (m)   the Satellite Lease Arrangements.

         SECTION 5.19. Employee Contracts and Arrangements. Neither the Borrower
nor  any of its  Subsidiaries  will  enter  into  any  employment  contracts  or
arrangements whose terms,  including salaries,  benefits and other compensation,
are not normal and customary and  commercially  reasonable for companies of like
size and circumstances.

         SECTION 5.20.  Investments.  Neither  the Borrower nor any other member
of the Borrower  Group will make or acquire any  Investment  in any Person other
than:




                                       48

<PAGE>



          (a) Investments in Persons which are Subsidiaries on the date hereof;

          (b) Cash Equivalents; and

          (c) any Investment not otherwise permitted by the foregoing clauses of
this Section if,  immediately  after such  Investment  is made or acquired,  the
aggregate  net book value of all  Investments  permitted by this clause (c) does
not exceed $10,000,000.

         SECTION 5.21. Transactions with Affiliates. Except where such Affiliate
is a member of the Borrower  Group,  the Borrower  will not, and will not permit
any  Subsidiary  to,  directly  or  indirectly,  (i) pay any funds to or for the
account of any Affiliate,  (ii) make any investment in any Affiliate (whether by
acquisition of stock or indebtedness,  by loan,  advance,  transfer of property,
guarantee  or  other  agreement  to  pay,  purchase  or  service,   directly  or
indirectly,  any Indebtedness,  or otherwise),  (iii) lease,  sell,  transfer or
otherwise dispose of any assets,  tangible or intangible,  to any Affiliate,  or
(iv) participate in, or effect,  any transaction  with any Affiliate,  except in
each  case on an  arm's-length  basis on terms  at  least  as  favorable  to the
Borrower or such  Subsidiary as could have been obtained from a third party that
was not an  Affiliate  or as  otherwise  expressly  approved  in  writing by the
Required Banks.

         SECTION 5.22. Compliance with ERISA. The Borrower shall not directly or
indirectly,  and shall not permit any member of the Controlled Group directly or
indirectly (i) to terminate, any Qualified Plan subject to Title IV of ERISA, so
as to result in any material (in the opinion of the Required Banks) liability to
the Borrower or any member of the Controlled  Group, (ii) to permit to exist any
ERISA  Event,  which  presents  the risk of a  material  (in the  opinion of the
Required  Banks)  liability of any member of the Controlled  Group,  or (iii) to
make a complete or partial withdrawal (within the meaning of ERISA Section 4201)
from any  Multiemployer  Plan so as to result in any material (in the opinion of
the  Required  Banks)  liability to any member of the  Controlled  Group or (iv)
permit the  present  value of all  nonforfeitable  accrued  benefits  under each
Qualified  Plan  (using  the  actuarial  assumptions  utilized  by the PBGC upon
termination  of a Qualified  Plan)  materially  (in the opinion of the  Required
Banks) to exceed the fair market  value of  Qualified  Plan assets  allocable to
such benefits, all determined as of the most recent valuation date for each such
Qualified Plan.

         SECTION  5.23.  Restricted  Payments.  The Borrower will not declare or
make any dividend  payment or other  distribution of assets,  properties,  cash,
rights,  obligations  or securities on account of any shares of any class of its
capital stock or purchase,  redeem or otherwise acquire for value (or permit any





                                       49

<PAGE>


member of the  Borrower  Group to do so) any shares of its capital  stock or any
warrants,   rights  or  options  to  acquire  such  shares,   now  or  hereafter
outstanding.

         SECTION 5.24.  Accounting Changes.  The Borrower will not, and will not
permit any Subsidiary to, make any  significant  change in accounting  treatment
and reporting  practices,  except as required by GAAP, or change the fiscal year
of the Borrower or any of its Subsidiaries.

         SECTION 5.25.  Limitation on Indebtedness.  The Borrower shall not, and
shall not permit any Subsidiary  (other than AMRC Holdings and  Subsidiaries  of
AMRC  Holdings)  to,  create,  incur,  assume,  guaranty,  suffer to  exist,  or
otherwise  become or remain  directly or indirectly  liable with respect to, any
Indebtedness, except for:

          (a)  accounts  payable to trade  creditors  for goods and services and
current  operating  liabilities  (not the  result  of the  borrowing  of  money)
incurred in the ordinary course of the Borrower's or the Subsidiary's  business,
as the case may be, in  accordance  with  customary  terms and paid  within  the
specified time,  unless  contested in good faith by appropriate  proceedings and
reserved for in accordance with GAAP;

          (b)   Indebtedness represented by Rate Contracts;

          (c)   income taxes payable and deferred taxes;

          (d)   accrued expenses and deferred income;

          (e)  Indebtedness  under the Senior  Notes in an  aggregate  principal
amount not to exceed $335,000,000 and Contingent Obligations of the Borrower and
of AMSC Acquisition  Company's  Subsidiaries in respect thereof (such Contingent
Obligations  of the  Borrower to be  subordinated  as  described in the Offering
Memorandum);

          (f)   Indebtedness under the Revolving Credit Agreement;

          (g)  Contingent  Obligations  incurred  in  connection  with any lease
financing of mobile  communications  terminals,  not exceeding $5,000,000 in the
aggregate in principal amount;

          (h)  Indebtedness  outstanding on the Effective Date and identified on
Schedule 5.25;





                                       50

<PAGE>



          (i) Indebtedness under the Financial Management Account Line of Credit
of the Borrower  payable to the order of Wachovia Bank of North Carolina,  N.A.,
in an aggregate principal amount at any time not exceeding $2,500,000; and

          (j)  Indebtedness   incurred  to  finance  in-orbit  insurance  in  an
aggregate amount outstanding at any time not to exceed $6,000,000;

          (k) Vendor Financing  Indebtedness in an aggregate amount  outstanding
at any time not to exceed $10,000,000; and

          (l) any other Indebtedness incurred after the Effective Date; provided
that the aggregate  outstanding  principal amount of all such Indebtedness shall
not at any time exceed $15,000,000.



                                    ARTICLE 6
                                    DEFAULTS

          SECTION  6.01.  Events  of  Default.  If one or more of the  following
events ("Events of Default") shall have occurred and be continuing:

          (a) the Borrower  shall fail to pay any principal of any Loan when due
or any  interest,  any fees or any other  amount  payable  hereunder  within two
Business Days of the date when due, or one or more Shareholder  Guarantors shall
have made more than two capital  contributions or Investments in the Borrower or
any Subsidiary thereof (or more than one during any twelve-month period) for the
principal  purpose of permitting  the Borrower to pay any  principal,  interest,
fees or other amounts payable hereunder;

          (b) the  Borrower  shall  fail to  observe  or  perform  any  covenant
contained  in Article 5, other than those  contained  in Sections  5.01  through
5.05, 5.07 through 5.10 and 5.16;

          (c) the  Borrower  shall fail to observe or perform  any  covenant  or
agreement contained in this Agreement (other than those covered by clause (a) or
(b) above) for 20 days after  notice  thereof has been given to the  Borrower by
the Administrative Agent at the request of any Bank;

          (d) any representation,  warranty,  certification or statement made by
the Borrower or a Subsidiary of the Borrower in this Agreement or any other Loan
Document or in any certificate, financial statement or  other document delivered




                                       51

<PAGE>



pursuant to this  Agreement  shall prove to have been  incorrect in any material
respect when made (or deemed made);

          (e) the Borrower or any  Subsidiary of the Borrower shall fail to make
any  payment  in  respect  of (x) any  obligation  under  the  Revolving  Credit
Agreement  or (y) any other  Indebtedness  or  Contingent  Obligation  having an
aggregate  principal and face amount of more than $5,000,000,  in each case when
due (whether by scheduled maturity, required prepayment, acceleration, demand or
otherwise)  and such  failure  continues  after the  applicable  grace period or
notice period, if any, specified in the document relating thereto;

          (f)  any  event  or  condition   shall  occur  which  results  in  the
acceleration of the maturity of any  Indebtedness  or Contingent  Obligation (x)
under the Revolving Credit Agreement or (y) any other Indebtedness or Contingent
Obligation of the Borrower or any Subsidiary of the Borrower having an aggregate
principal or face amount of more than $5,000,000 or enables (or, with the giving
of  notice  or lapse of time or  both,  would  enable)  the  holder  of any such
Indebtedness  or  Contingent  Obligation  or any Person  acting on such holder's
behalf to accelerate the maturity thereof;

          (g)  the  Borrower  or  any  Principal  Subsidiary  shall  commence  a
voluntary case or other proceeding seeking liquidation,  reorganization or other
relief with respect to itself or its debts under any  bankruptcy,  insolvency or
other  similar law now or  hereafter in effect or seeking the  appointment  of a
trustee, receiver, liquidator,  custodian or other similar official of it or any
substantial part of its property,  or shall consent to any such relief or to the
appointment of or taking  possession by any such official in an involuntary case
or other proceeding commenced against it, or shall make a general assignment for
the  benefit  of  creditors,  or shall fail  generally  to pay its debts as they
become  due,  or  shall  take  any  corporate  action  to  authorize  any of the
foregoing;

          (h) an involuntary case or other proceeding shall be commenced against
the Borrower or any Principal Subsidiary seeking liquidation,  reorganization or
other relief with respect to it or its debts under any bankruptcy, insolvency or
other  similar law now or  hereafter in effect or seeking the  appointment  of a
trustee, receiver, liquidator,  custodian or other similar official of it or any
substantial part of its property,  and such involuntary case or other proceeding
shall remain  undismissed  and unstayed for a period of 60 days; or an order for
relief shall be entered against the Borrower or any Principal  Subsidiary  under
the federal bankruptcy laws as now or hereafter in effect;

          (i) (1) any member of the Controlled Group shall fail to pay when due,
after the expiration of any applicable  grace period,  any  installment  payment
with respect to its withdrawal  liability  under a  Multiemployer  Plan; (2) any





                                       52

<PAGE>


member  of  the  Controlled   Group  shall  fail  to  satisfy  its  contribution
requirements  under Section 412(c)(11) of the Code, whether or not it has sought
a waiver  under  Section  412(d) of the Code;  (3) in the case of an ERISA Event
involving the withdrawal from a Plan of a "substantial  employer" (as defined in
Section  4001(a)(2) or Section  4062(e) of ERISA),  the  withdrawing  employer's
proportionate  share of that Plan's  Unfunded  Pension  Liabilities is more than
$5,000,000  or 10% of its net  worth,  if  greater;  (4) in the case of an ERISA
Event involving the complete or partial  withdrawal  from a Multiemployer  Plan,
the  withdrawing  employer has  incurred a withdrawal  liability in an aggregate
amount exceeding $5,000,000 or 10% of its net worth, if greater; (5) in the case
of an ERISA  Event not  described  in clause (3) or (4),  the  Unfunded  Pension
Liabilities  of the relevant  Plan or Plans exceed  $5,000,000 or 10% of its net
worth,  if greater;  (6) a Plan that is intended to be qualified  under  Section
401(a) of the Code shall lose its qualification,  and the loss can reasonably be
expected  to  impose  on any  member  of the  Controlled  Group  liability  (for
additional taxes, to Plan participants, or otherwise) in the aggregate amount of
$5,000,000 or 10% of its net worth, if greater or more; (7) the  commencement or
increase of  contributions  to, the adoption of, or the  amendment of a Plan by,
any member of the  Controlled  Group shall  result in a net increase in unfunded
liabilities to the Borrower or an ERISA Affiliate in excess of $5,000,000 or 10%
of net worth,  if greater;  or (8) the  occurrence of any  combination of events
listed in clauses  (3)  through (7) that  involves a net  increase in  aggregate
Unfunded Pension Liabilities and unfunded liabilities in excess of $5,000,000 or
10% of its net worth, if greater;

          (j) one or more final  judgments,  orders or decrees  shall be entered
against  the  Borrower  or any member of the  Borrower  Group  involving  in the
aggregate  a  liability  (not  fully  covered by  insurance  and as to which the
insurer has not acknowledged liability) more than an amount equal to the greater
of (i) $5,000,000  and (ii) 10% of the Borrower's net worth,  and the same shall
remain unvacated, undischarged, unstayed or unbonded pending appeal for a period
of 60 days after the entry thereof; or

          (k) any  non-monetary  judgment,  order or  decree  shall be  rendered
against  the  Borrower or any of its  Subsidiaries  which  could  reasonably  be
expected to have a Material Adverse Effect,  and enforcement  proceedings  shall
have been commenced by any Person upon such judgment or order which shall remain
unstayed for any period of 10 consecutive days or more; or

          (l) (i) any provision of the Security and Pledge  Agreement  shall for
any reason cease to be valid and binding on or enforceable against the Borrower,
if the effect  thereof  may  materially  deprive the Banks and the Agents of the
benefits of the Collateral  covered  thereby,  or the Borrower shall so state in
writing or bring an action to limit its  obligations or liabilities  thereunder;





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<PAGE>


(ii) the Security and Pledge Agreement shall for any reason (other than pursuant
to, or  contemplated  by, the terms  thereof)  cease to create a valid  security
interest in the  Collateral  purported  to be covered  thereby or such  security
interest  shall for any reason cease to be a perfected and (except for Permitted
Liens arising by operation of law) first priority security  interest;  (iii) any
of the  outstanding  Obligations of the Borrower  hereunder shall not be Secured
Obligations  (as defined in the  Security and Pledge  Agreement);  or (iv) there
shall occur an event of loss which, together with all other events of loss since
the Effective  Date,  results in a reduction in the value (as  determined in the
reasonable opinion of the Required Banks) of the Collateral of $2,500,000 net of
any cash proceeds received by the Borrower in respect of such event or events of
loss; or

          (m) the FCC or any other  Governmental  Authority shall revoke or fail
to renew any FCC License or any other material  license,  permit or franchise of
the Borrower or any of its  Subsidiaries;  the Borrower or any Subsidiary  shall
for any reason lose any FCC  License or any other  material  license,  permit or
franchise;  or the Borrower or any Subsidiary shall suffer the imposition of any
restraining order, escrow, suspension or impound of funds in connection with any
proceeding  (judicial or administrative)  with respect to any FCC License or any
other material license, permit or franchise;

          (n) there shall occur and be continuing a Material Adverse Effect;

          (o) the Borrower  shall breach or default  under any Rate  Contract to
which any Bank is a party,  if the effect of such  breach or default is to allow
the Bank to  proceed  against  the  Borrower  to  satisfy  any claim of the Bank
against the Borrower in respect of such Rate Contract;

          (p)   there shall occur a Change in Control;

          (q) any Shareholder  Guarantor (other than Baron Capital,  so long as,
with respect to any failure to make a payment described in clause (ii) below, an
amount equal to such payment is paid under the Baron  Capital  Letter of Credit)
shall fail to make any payment (i) in respect of any  Indebtedness or Contingent
Obligation having an aggregate principal or face amount of more than $75,000,000
or (ii) under its Shareholder  Guaranty when due (whether by scheduled maturity,
required  prepayment,  acceleration,  demand  or  otherwise)  and  such  failure
continues after the applicable grace period or notice period, if any,  specified
in the document relating thereto;

          (r)  any  event  or  condition   shall  occur  which  results  in  the
acceleration of the maturity of any Indebtedness or Contingent Obligation of any
Shareholder  Guarantor (other than Baron Capital) having an aggregate  principal





                                       54

<PAGE>


or  face  amount  of  more  than  $75,000,000  or  enables  the  holder  of such
Indebtedness  or  Contingent  Obligation  or any Person  acting on such holder's
behalf to accelerate the maturity thereof;

          (s) any  Shareholder  Guaranty or the Baron  Capital  Letter of Credit
shall for any reason be revoked or invalidated or otherwise  cease to be in full
force and  effect  (other  than in  accordance  with its terms as the  result of
performance  in  full  of  the  relevant  Shareholder   Guarantor's  obligations
thereunder)  or any  Shareholder  Guarantor  (other than Baron Capital) shall so
assert in writing or any  Shareholder  Guarantor  shall bring an action to limit
its liabilities thereunder;

          (t) Hughes' senior unsecured long-term securities (without third-party
credit  enhancement)  shall not be rated  Baa3 or above by  Moody's  and BBB- or
above by S&P; or

          (u) Hughes and either other Shareholder  Guarantor shall have notified
any of the  Agents  and  the  banks  of the  existence  of a  Guaranty  Issuance
Agreement Event of Default;

then, and in every such event, the  Administrative  Agent shall (i) if requested
by Banks having more than 50% in aggregate amount of the Commitments,  by notice
to the Borrower  terminate the Commitments  and they shall thereupon  terminate,
and (ii) if requested by Banks holding more than 50% of the aggregate  principal
amount of the Loans, by notice to the Borrower  declare the Loans (together with
accrued  interest  thereon)  to  be,  and  the  Loans  shall  thereupon  become,
immediately due and payable without presentment, demand, protest or other notice
of any kind,  all of which are hereby waived by the  Borrower;  provided that in
the case of any of the  Events of Default  specified  in clause (g) or (h) above
with  respect to the  Borrower,  without any notice to the Borrower or any other
act by the  Administrative  Agent or the Banks, the Commitments  shall thereupon
terminate and the Loans  (together with accrued  interest  thereon) shall become
immediately due and payable without presentment, demand, protest or other notice
of any kind,  all of which are  hereby  waived by the  Borrower.  If any  amount
payable under this Agreement shall not be paid when due, then the Administrative
Agent  shall,  if  requested  by Banks  holding  more than 50% of the  aggregate
principal  amount  (excluding any Loans held by the Borrower or any  Shareholder
Guarantor or any Affiliate of the  foregoing) of the Tranche A Loans,  Tranche B
Loans or Tranche C Loans, as the case may be, demand payment  therefor under the
relevant Shareholder Guaranty.

         SECTION 6.02. Notice of Default.  The  Administrative  Agent shall give
notice to the Borrower under Section 6.01(c) promptly upon being requested to do
so by any Bank and shall thereupon notify all the Banks thereof.




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<PAGE>



                                    ARTICLE 7
                                   THE AGENTS

         SECTION 7.01.  Appointment  and  Authorization.  Each Bank  irrevocably
appoints  and  authorizes  each Agent to take such action as agent on its behalf
and to exercise such powers under this Agreement,  the Notes and each other Loan
Document as are delegated to such Agent by the terms hereof or thereof, together
with all such powers as are reasonably incidental thereto.

         SECTION 7.02.  Agents and Affiliates.  Morgan Guaranty Trust Company of
New York shall have the same rights and powers under this Agreement as any other
Bank and may exercise or refrain from  exercising the same as though it were not
an Agent, and each of Toronto Dominion  (Texas),  Inc. and Morgan Guaranty Trust
Company of New York and its affiliates may accept  deposits from, lend money to,
and generally engage in any kind of business with the Borrower or any Subsidiary
or affiliate of the Borrower as if it were not an Agent.

         SECTION 7.03. Action by Agents. The obligations of the Agents hereunder
are only those  expressly set forth herein.  Without  limiting the generality of
the foregoing,  the Agents shall not be required to take any action with respect
to any Default, except as expressly provided in Article 6.

         SECTION 7.04.  Consultation with Experts. Either Agent may consult with
legal  counsel  (who  may be  counsel  for  the  Borrower),  independent  public
accountants  and other  experts  selected  by it and shall not be liable for any
action taken or omitted to be taken by it in good faith in  accordance  with the
advice of such counsel, accountants or experts.

         SECTION 7.05. Liability of Agents. No Agent or any of its affiliates or
any of their respective directors, officers, agents or employees shall be liable
for any  action  taken or not taken by it in  connection  herewith  (i) with the
consent or at the  request of the  Required  Banks or (ii) in the absence of its
own gross negligence or willful misconduct. No Agent or any of its affiliates or
any of their  respective  directors,  officers,  agents  or  employees  shall be
responsible  for or have any duty to  ascertain,  inquire into or verify (i) any
statement,  warranty or representation made in connection with this Agreement or
the  Borrowing  hereunder;  (ii) the  performance  or  observance  of any of the
covenants or agreements of the Borrower; (iii) the satisfaction of any condition
specified in Article 3, except  receipt of items required to be delivered to the
Documentation Agent; or (iv) the validity,  effectiveness or genuineness of this
Agreement,  the Notes or any other instrument or writing furnished in connection
herewith.  No Agent shall  incur any  liability  by acting in reliance  upon any





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<PAGE>


notice, consent,  certificate,  statement, or other writing (which may be a bank
wire,  telex,  facsimile  transmission or similar writing)  believed by it to be
genuine or to be signed by the proper party or parties.

         SECTION 7.06.  Indemnification.  Each Bank shall, ratably in accordance
with its Commitment,  indemnify each Agent,  its affiliates and their respective
directors,  officers,  agents and employees (to the extent not reimbursed by the
Borrower) against any cost, expense (including counsel fees and  disbursements),
claim,  demand,  action,  loss or  liability  (except  such as result  from such
indemnitee's  gross  negligence or willful  misconduct) that such indemnitee may
suffer or incur in connection with this Agreement or any action taken or omitted
by such indemnitee hereunder.

         SECTION 7.07.  Credit  Decision.  Each Bank  acknowledges  that it has,
independently  and without  reliance  upon either  Agent or any other Bank,  and
based on such documents and information as it has deemed  appropriate,  made its
own credit  analysis and decision to enter into this  Agreement.  Each Bank also
acknowledges that it will,  independently and without reliance upon either Agent
or any other Bank, and based on such documents and  information as it shall deem
appropriate at the time,  continue to make its own credit decisions in taking or
not taking any action under this Agreement.

         SECTION 7.08.  Successor Agent.  Either Agent may resign at any time by
giving notice thereof to the Banks and the Borrower.  Upon any such resignation,
the  Required  Banks  shall have the right to appoint a successor  Agent.  If no
successor  Agent shall have been so appointed by the Required  Banks,  and shall
have accepted such  appointment,  within 30 days after the retiring  Agent gives
notice of  resignation,  then the  retiring  Agent may,  on behalf of the Banks,
appoint a  successor  Agent,  which  shall be a  commercial  bank  organized  or
licensed  under the laws of the United States of America or of any State thereof
and having a combined  capital  and  surplus of at least  $50,000,000.  Upon the
acceptance of its  appointment  as Agent  hereunder by a successor  Agent,  such
successor Agent shall thereupon succeed to and become vested with all the rights
and duties of the retiring  Agent,  and the retiring  Agent shall be  discharged
from  its  duties  and  obligations   hereunder.   After  any  retiring  Agent's
resignation  hereunder as Agent,  the  provisions of this Article shall inure to
its  benefit as to any  actions  taken or omitted to be taken by it while it was
Agent.

         SECTION 7.09.  Agents' Fees.  The Borrower  shall pay to each Agent for
its own  account  fees in the amounts  and at the times  previously  agreed upon
between the Borrower and such Agent.






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<PAGE>



                                    ARTICLE 8
                             CHANGE IN CIRCUMSTANCES

          SECTION  8.01.  Basis for  Determining  Interest  Rate  Inadequate  or
Unfair.  If on or  prior  to the  first  day  of any  Interest  Period  for  any
Euro-Dollar Loan:

          (a) the  Administrative  Agent is advised by the Reference  Banks that
deposits in dollars (in the  applicable  amounts)  are not being  offered to the
Reference Banks in the London interbank market for such Interest Period, or

          (b) Banks having 50% or more of the aggregate  principal amount of the
affected  Loans  advise  the  Administrative  Agent  that  the  Adjusted  London
Interbank  Offered  Rate as  determined  by the  Administrative  Agent  will not
adequately  and  fairly  reflect  the  cost  to  such  Banks  of  funding  their
Euro-Dollar Loans for such Interest Period,

the Administrative Agent shall forthwith give notice thereof to the Borrower and
the Banks,  whereupon until the Administrative  Agent notifies the Borrower that
the  circumstances  giving  rise to such  suspension  no longer  exist,  (i) the
obligations  of the Banks to make  Euro-Dollar  Loans or to  continue or convert
outstanding  Loans as or into Euro-Dollar Loans shall be suspended and (ii) each
outstanding  Euro-Dollar  Loan shall be  converted  into a Base Rate Loan on the
last day of the then current  Interest  Period  applicable  thereto.  Unless the
Borrower notifies the  Administrative  Agent at least two Domestic Business Days
before the date of the Borrowing,  if it is to be a Euro-Dollar  Borrowing,  for
which the Notice of Borrowing  has  previously  been given that it elects not to
borrow  on such  date,  the  Borrowing  shall  instead  be  made as a Base  Rate
Borrowing.  The  Administrative  Agent  shall  notify  the  Borrower  as soon as
reasonably  possible upon learning  that the  circumstances  giving rise to such
suspension no longer exist.

         SECTION 8.02.  Illegality.  If, on or after the date of this Agreement,
the adoption of any  applicable  law, rule or  regulation,  or any change in any
applicable  law,  rule or  regulation,  or any change in the  interpretation  or
administration thereof by any governmental authority, central bank or comparable
agency charged with the interpretation or administration  thereof, or compliance
by any Bank (or its  Euro-Dollar  Lending  Office) with any request or directive
(whether or not having the force of law) of any such authority,  central bank or
comparable  agency  shall make it  unlawful or  impossible  for any Bank (or its
Euro-Dollar  Lending Office) to make, maintain or fund its Euro-Dollar Loans and
such Bank shall so notify the  Administrative  Agent, the  Administrative  Agent
shall  forthwith  give  notice  thereof  to the other  Banks  and the  Borrower,





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<PAGE>


whereupon  until such Bank  notifies the Borrower and the  Administrative  Agent
that the  circumstances  giving rise to such  suspension  no longer  exist,  the
obligation of such Bank to make  Euro-Dollar  Loans,  or to convert  outstanding
Loans into Euro-Dollar  Loans,  shall be suspended.  Before giving any notice to
the Administrative  Agent pursuant to this Section,  such Bank shall designate a
different Euro-Dollar Lending Office if such designation will avoid the need for
giving  such notice and will not, in the  judgment  of such Bank,  be  otherwise
disadvantageous  to such Bank. If such notice is given, each Euro-Dollar Loan of
such Bank then outstanding  shall be converted to a Base Rate Loan either (a) on
the last day of the then current Interest Period  applicable to such Euro-Dollar
Loan if such Bank may  lawfully  continue to maintain and fund such Loan to such
day or (b)  immediately  if such Bank shall  determine  that it may not lawfully
continue to maintain and fund such Loan to such day.  Each Bank shall notify the
Administrative  Agent and the Borrower as soon as reasonably  possible after the
circumstances  giving  rise to any  suspension  by such Bank  described  in this
Section 8.02 no longer exist.

         SECTION 8.03. Increased Cost and Reduced Return. (a) If on or after the
date hereof,  the adoption of any  applicable  law, rule or  regulation,  or any
change  in  any  applicable  law,  rule  or  regulation,  or any  change  in the
interpretation or administration thereof by any governmental authority,  central
bank or comparable  agency  charged with the  interpretation  or  administration
thereof,  or compliance by any Bank (or its Applicable  Lending Office) with any
request  or  directive  (whether  or not  having  the  force of law) of any such
authority,  central  bank or  comparable  agency  shall  impose,  modify or deem
applicable any reserve  (including,  without  limitation,  any such  requirement
imposed by the Board of Governors of the Federal Reserve  System,  but excluding
any such requirement included in an applicable  Euro-Dollar Reserve Percentage),
special deposit,  insurance assessment or similar requirement against assets of,
deposits  with or for the  account of, or credit  extended  by, any Bank (or its
Applicable  Lending  Office)  or shall  impose  on any  Bank (or its  Applicable
Lending Office) or the London interbank market any other condition affecting its
Euro-Dollar  Loans, its Note or its obligation to make Euro-Dollar Loans and the
result  of any of the  foregoing  is to  increase  the cost to such Bank (or its
Applicable  Lending Office) of making or maintaining any Euro-Dollar Loan, or to
reduce  the  amount  of any sum  received  or  receivable  by such  Bank (or its
Applicable  Lending  Office) under this Agreement or under its Note with respect
thereto,  by an amount deemed by such Bank to be material,  then, within 15 days
after  demand  by  such  Bank  (with a copy to the  Administrative  Agent),  the
Borrower  shall pay to such  Bank such  additional  amount  or  amounts  as will
compensate  such Bank for such increased cost or reduction;  provided,  however,
that in the case of an increase  referred to above  resulting from the published
interpretation by a governmental authority,  such Bank shall be entitled to make
demand  on  the  Borrower  in  respect  thereof  only  within  180  days  of the
publication of such interpretation.




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<PAGE>



          (b) If any Bank shall have determined that, after the date hereof, the
adoption of any applicable law, rule or regulation  regarding  capital adequacy,
or any  change  in any  such  law,  rule or  regulation,  or any  change  in the
interpretation or administration thereof by any governmental authority,  central
bank or comparable  agency  charged with the  interpretation  or  administration
thereof,  or any request or directive regarding capital adequacy (whether or not
having  the  force of law) of any such  authority,  central  bank or  comparable
agency,  has or would have the effect of reducing  the rate of return on capital
of such  Bank  (or its  Parent)  as a  consequence  of such  Bank's  obligations
hereunder  to a level  below  that which  such Bank (or its  Parent)  could have
achieved  but for such  adoption,  change,  request or  directive  (taking  into
consideration its policies with respect to capital adequacy) by an amount deemed
by such Bank to be material, then from time to time, within 15 days after demand
by such Bank (with a copy to the  Administrative  Agent), the Borrower shall pay
to such Bank such additional  amount or amounts as will compensate such Bank (or
its  Parent)  for  such  reduction;  provided,  however,  that in the case of an
increase  referred to above  resulting  from the published  interpretation  by a
governmental  authority,  such  Bank  shall be  entitled  to make  demand on the
Borrower  in respect  thereof  only within 180 days of the  publication  of such
interpretation.

          (c) Each Bank will promptly notify the Borrower and the Administrative
Agent of any event of which it has knowledge,  occurring  after the date hereof,
which will entitle such Bank to  compensation  pursuant to this Section and will
designate a different  Lending  Office if such  designation  will avoid the need
for, or reduce the amount of, such compensation and will not, in the judgment of
such Bank, be otherwise  disadvantageous to such Bank. A certificate of any Bank
claiming compensation under this Section and setting forth the additional amount
or amounts to be paid to it  hereunder  shall be  conclusive  in the  absence of
manifest  error.  In determining  such amount,  such Bank may use any reasonable
averaging  and  attribution  methods.  Each Bank will notify the  Administrative
Agent and the Borrower as soon as  reasonably  possible  after any  circumstance
entitling such Bank to  compensation  pursuant to this Section 8.03(c) no longer
exists.

         SECTION 8.04.  Taxes.  (a) For the purposes of this Section 8.04 , the
following terms have the following meanings:

         "Taxes"  means any and all  present or future  taxes,  duties,  levies,
imposts, deductions,  charges or withholdings with respect to any payment by the
Borrower,  as the case may be, pursuant to this Agreement or under any Note, and
all liabilities with respect thereto, excluding (i) in the case of each Bank and
Agent,  taxes  imposed on its income,  and franchise or similar taxes imposed on
it, by a  jurisdiction  under the laws of which  such Bank or Agent (as the case





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<PAGE>


may be) is organized or in which its principal  executive  office is located or,
in the case of each Bank, in which its Applicable  Lending Office is located and
(ii) in the case of each Bank, any United States withholding tax imposed on such
payments  but only to the  extent  that such Bank is  subject  to United  States
withholding tax at the time such Bank first becomes a party to this Agreement.

         "Other  Taxes" means any present or future stamp or  documentary  taxes
and any other  excise or property  taxes,  or similar  charges or levies,  which
arise from any payment made pursuant to this Agreement or under any Note or from
the  execution or delivery of, or otherwise  with respect to, this  Agreement or
any Note.

          (b) Any and all  payments by the Borrower to or for the account of any
Bank or Agent  hereunder or under any Note shall be made without  deduction  for
any Taxes or Other Taxes;  provided  that, if the Borrower  shall be required by
law to  deduct  any Taxes or Other  Taxes  from any such  payments,  (i) the sum
payable  shall be  increased  as  necessary  so that after  making all  required
deductions  (including  deductions  applicable to additional  sums payable under
this  Section)  such Bank or Agent (as the case may be) receives an amount equal
to the sum it would have  received had no such  deductions  been made,  (ii) the
Borrower  shall  make such  deductions,  (iii) the  Borrower  shall pay the full
amount  deducted  to the  relevant  taxation  authority  or other  authority  in
accordance  with  applicable  law and (iv) the  Borrower  shall  furnish  to the
Administrative  Agent, at its address referred to in Section 9.01 , the original
or a certified copy of a receipt evidencing payment thereof.

          (c) The Borrower  agrees to indemnify each Bank and Agent for the full
amount of Taxes or Other  Taxes  (including,  without  limitation,  any Taxes or
Other Taxes  imposed or asserted by any  jurisdiction  on amounts  payable under
this  Section) paid by such Bank or Agent (as the case may be) and any liability
(including penalties, interest and expenses, other than those resulting from any
act or failure to act by such Bank) arising  therefrom or with respect  thereto.
This  indemnification  shall be paid within 15 days after such Bank or Agent (as
the case may be) makes demand therefor.

          (d) Each Bank organized  under the laws of a jurisdiction  outside the
United  States,  on or prior to the date of its  execution  and delivery of this
Agreement in the case of each Bank listed on the  signature  pages hereof and on
or prior to the date on which it becomes a Bank in the case of each other  Bank,
and from time to time  thereafter  if requested in writing by the Borrower  (but
only so long as such Bank remains  lawfully  able to do so),  shall  provide the
Borrower and the Administrative Agent with Internal Revenue Service form 1001 or
4224, as appropriate,  or any successor form prescribed by the Internal  Revenue
Service,  certifying  that such Bank is entitled to benefits under an income tax
treaty to which the United  States is a party which exempts the Bank from United





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States  withholding  tax or reduces the rate of  withholding  tax on payments of
interest for the account of such Bank or certifying  that the income  receivable
pursuant to this Agreement is effectively  connected with the conduct of a trade
or business in the United States.

          (e) For any period with  respect to which a Bank has failed to provide
the Borrower or the  Administrative  Agent with the appropriate form pursuant to
Section  8.04(d)  (unless  such  failure  is due to a change in  treaty,  law or
regulation  occurring  subsequent to the date on which such form  originally was
required to be  provided),  such Bank shall not be  entitled to  indemnification
under  Section  8.04(b) or 8.04(c) with  respect to Taxes  imposed by the United
States;  provided that if a Bank, which is otherwise exempt from or subject to a
reduced rate of withholding tax, becomes subject to Taxes because of its failure
to deliver a form required hereunder, the Borrower shall take such steps as such
Bank shall reasonably request to assist such Bank to recover such Taxes.

          (f) If the  Borrower is required to pay  additional  amounts to or for
the account of any Bank pursuant to this Section, then such Bank will change the
jurisdiction of its Applicable  Lending Office if, in the judgment of such Bank,
such change (i) will eliminate or reduce any such  additional  payment which may
thereafter accrue and (ii) is not otherwise disadvantageous to such Bank.

         SECTION  8.05.  Base Rate Loans  Substituted  for Affected  Euro-Dollar
Loans. If (i) the obligation of any Bank to make, or convert  outstanding  Loans
to,  Euro-Dollar  Loans has been suspended  pursuant to Section 8.02 or (ii) any
Bank has demanded  compensation  under  Section 8.03 or 8.04 with respect to its
Euro-Dollar Loans and the Borrower shall, by at least five Euro-Dollar  Business
Days' prior notice to such Bank through the  Administrative  Agent, have elected
that the provisions of this Section shall apply to such Bank,  then,  unless and
until such Bank notifies the Borrower that the circumstances giving rise to such
suspension or demand for compensation no longer exist:

          (a) all  Loans  which  would  otherwise  be  made by such  Bank as (or
continued as or converted  into)  Euro-Dollar  Loans shall  instead be Base Rate
Loans (on which interest and principal shall be payable  contemporaneously  with
the related Euro-Dollar Loans of the other Banks); and

          (b) after each of its Euro-Dollar  Loans has been repaid (or converted
to a Base Rate Loan), all payments of principal which would otherwise be applied
to repay such  Euro-Dollar  Loans  shall be applied to repay its Base Rate Loans
instead.





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<PAGE>



If such Bank  notifies the Borrower that the  circumstances  giving rise to such
notice no longer apply,  the principal  amount of each such Base Rate Loan shall
be converted  into a  Euro-Dollar  Loan on the first day of the next  succeeding
Interest Period applicable to the related Euro-Dollar Loans of the other Banks.



                                    ARTICLE 9
                                  MISCELLANEOUS

         SECTION 9.01. Notices.  All notices,  requests and other communications
to any party  hereunder  shall be in writing  (including  bank  wire,  facsimile
transmission  or similar  writing) and shall be given to such party:  (a) in the
case of the Borrower or either  Agent,  at its address or  facsimile  number set
forth on the signature pages hereof, (b) in the case of any Bank, at its address
or facsimile number set forth in its Administrative  Questionnaire or (c) in the
case of any party,  such other  address  or  facsimile  number as such party may
hereafter specify for the purpose by notice to the Agents and the Borrower. Each
such notice,  request or other  communication shall be effective (i) if given by
facsimile  transmission,  when  transmitted to the facsimile number specified in
this Section and confirmation of receipt is received,  (ii) if given by mail, 72
hours  after such  communication  is  deposited  in the mails  with first  class
postage  prepaid,  addressed  as aforesaid or (iii) if given by any other means,
when delivered at the address  specified in this Section;  provided that notices
to the Administrative  Agent under Article 2 or Article 8 shall not be effective
until received.

         SECTION  9.02.  No Waivers.  No failure or delay by either Agent or any
Bank in  exercising  any right,  power or privilege  hereunder or under any Note
shall  operate as a waiver  thereof  nor shall any  single or  partial  exercise
thereof  preclude any other or further  exercise  thereof or the exercise of any
other right,  power or privilege.  The rights and remedies herein provided shall
be cumulative and not exclusive of any rights or remedies provided by law.

         SECTION 9.03. Expenses; Indemnification. (a) The Borrower shall pay (i)
all  out-of-pocket  expenses  of  the  Agents,  including  reasonable  fees  and
disbursements  of  special  counsel  for the  Agents,  in  connection  with  the
preparation  and  administration  of  this  Agreement,  any  waiver  or  consent
hereunder or any amendment  hereof or any Default or alleged  Default  hereunder
and (ii) if an Event of Default occurs,  all out-of-pocket  expenses incurred by
each Agent and Bank, including (without  duplication) the fees and disbursements
of outside counsel and the allocated cost of inside counsel,  in connection with
such  Event  of  Default  and  collection,   bankruptcy,  insolvency  and  other
enforcement proceedings resulting therefrom.




                                       63

<PAGE>



          (b) The  Borrower  agrees to  indemnify  each  Agent  and Bank,  their
respective  affiliates  and  the  respective  directors,  officers,  agents  and
employees  of the  foregoing  (each an  "Indemnitee")  and hold each  Indemnitee
harmless from and against any and all liabilities,  losses,  damages,  costs and
expenses of any kind,  including,  without  limitation,  the reasonable fees and
disbursements of counsel, which may be incurred by such Indemnitee in connection
with any investigative,  administrative or judicial  proceeding  (whether or not
such  Indemnitee  shall be  designated a party  thereto)  brought or  threatened
relating to or arising out of this  Agreement  or any actual or proposed  use of
proceeds of Loans hereunder; provided that no Indemnitee shall have the right to
be indemnified  hereunder for such  Indemnitee's own gross negligence or willful
misconduct as determined by a court of competent jurisdiction.

         SECTION 9.04.  Sharing of Set-offs.  Each Bank agrees that if it shall,
by exercising any right of set-off or counterclaim or otherwise  (other than any
such right against a Shareholder Guarantor),  receive payment of a proportion of
the aggregate amount of principal and interest due with respect to any Note held
by it which is greater than the proportion received by any other Bank in respect
of the  aggregate  amount of principal and interest due with respect to any Note
held by such other Bank, the Bank receiving such proportionately greater payment
shall  purchase such  participations  in the Notes held by the other Banks,  and
such  other  adjustments  shall be  made,  as may be  required  so that all such
payments of principal  and interest  with respect to the Notes held by the Banks
shall be shared by the Banks pro rata;  provided  that  nothing in this  Section
shall  impair  the  right of any  Bank to  exercise  any  right  of  set-off  or
counterclaim it may have and to apply the amount subject to such exercise to the
payment of indebtedness of the Borrower other than its  indebtedness  hereunder.
The  Borrower  agrees,  to the  fullest  extent it may  effectively  do so under
applicable  law, that any holder of a  participation  in a Note,  whether or not
acquired pursuant to the foregoing arrangements,  may exercise rights of set-off
or counterclaim and other rights with respect to such  participation as fully as
if such holder of a participation  were a direct creditor of the Borrower in the
amount of such participation.

         SECTION 9.05.  Amendments and Waivers.  Any provision of this Agreement
or the Notes may be amended or waived if, but only if, such  amendment or waiver
is in writing and is signed by the Borrower and the Required  Banks (and, if the
rights or duties of an Agent are affected thereby, by such Agent); provided that
no such amendment or waiver shall,  unless signed by all the Banks, (a) increase
or decrease the  Commitment  of any Bank  (except for a ratable  decrease in the
Commitments of all Banks) or subject any Bank to any additional obligation,  (b)
reduce the principal of or rate of interest on any Loan, or any fees  hereunder,
(c)  postpone  the date fixed for any payment of principal of or interest on any
Loan, or any fees hereunder or for any scheduled reduction or termination of any





                                       64

<PAGE>


Commitment,  (d) release the  Borrower  from its  obligations  hereunder  or the
Shareholder Guarantors from their obligations under the Shareholders Guaranties,
(e)  release  all or  substantially  all of the  Collateral,  or (f)  change the
percentage of the Commitments or of the aggregate unpaid principal amount of the
Notes,  or the number of Banks,  which shall be required for the Banks or any of
them to take any  action  under  this  Section  or any other  provision  of this
Agreement.

         SECTION  9.06.  Successors  and  Assigns.  (a) The  provisions  of this
Agreement  shall be binding upon and inure to the benefit of the parties  hereto
and their  respective  successors and assigns,  except that the Borrower may not
assign or otherwise  transfer any of its rights under this Agreement without the
prior written consent of all Banks.

          (b) Any  Bank  may at any  time  grant  to one or more  banks or other
institutions (each a "Participant") participating interests in its Commitment or
any or all of  its  Loans.  In the  event  of  any  such  grant  by a Bank  of a
participating  interest  to a  Participant,  whether  or not upon  notice to the
Borrower and the Agents,  such Bank shall remain responsible for the performance
of its obligations hereunder,  and the Borrower and the Agents shall continue to
deal solely and directly  with such Bank in  connection  with such Bank's rights
and obligations under this Agreement.  Any agreement  pursuant to which any Bank
may grant  such a  participating  interest  shall  provide  that such Bank shall
retain  the sole right and  responsibility  to enforce  the  obligations  of the
Borrower  hereunder  including,  without  limitation,  the right to approve  any
amendment,  modification or waiver of any provision of this Agreement;  provided
that such  participation  agreement may provide that such Bank will not agree to
any modification, amendment or waiver of this Agreement described in clause (a),
(b),  (c),  (d) or (e) of the proviso to Section 9.05 without the consent of the
Participant.  The Borrower  agrees that each  Participant  shall,  to the extent
provided in its participation  agreement, be entitled to the benefits of Article
8 with respect to its  participating  interest.  An assignment or other transfer
which is not permitted by subsection  (c) or (d) below shall be given effect for
purposes  of this  Agreement  only to the  extent  of a  participating  interest
granted in accordance with this subsection (b).

          (c) Any Bank may at any time,  upon five Business Days' written notice
to each of the Agents,  assign to one or more banks or other  institutions (each
an "Assignee") all, or a proportionate part (equivalent to an initial Commitment
of not less than  $2,500,000) of all, of its rights and  obligations  under this
Agreement  and the  Notes,  and such  Assignee  shall  assume  such  rights  and
obligations, pursuant to an Assignment and Assumption Agreement in substantially
the form of Exhibit D hereto executed by such Assignee and such transferor Bank,
with  (and  subject  to)  the  subscribed   consent  of  the  Borrower  and  the
Administrative  Agent,  which  consent  shall in each  case not be  unreasonably
withheld;  provided  that (x) if an Assignee is an affiliate of such  transferor
Bank or was a Bank immediately prior to such assignment or




                                       65

<PAGE>



if the Assignee is a Shareholder  Guarantor purchasing Notes pursuant to Section
1(e) of a Shareholder  Guaranty,  no such consent shall be required and (y) such
Bank shall contemporaneously assign to such Assignee an equivalent percentage of
loans under the Revolving Credit Agreement.  Upon execution and delivery of such
instrument  and payment by such  Assignee to such  transferor  Bank of an amount
equal  to the  purchase  price  agreed  between  such  transferor  Bank and such
Assignee,  such Assignee  shall be a Bank party to this Agreement and shall have
all the rights and  obligations of a Bank with a Commitment as set forth in such
instrument of  assumption,  and the  transferor  Bank shall be released from its
obligations  hereunder  to a  corresponding  extent,  and no further  consent or
action by any party shall be required.  Upon the  consummation of any assignment
pursuant to this subsection (c), the transferor Bank, the  Administrative  Agent
and the Borrower shall make appropriate arrangements so that, if required, a new
Note is issued to the Assignee,  and the  transferor  Bank shall provide  prompt
written notice of such assignment to the Documentation Agent. In connection with
any such assignment,  the transferor Bank shall pay to the Administrative  Agent
an administrative fee for processing such assignment in the amount of $2,500. If
the Assignee is not incorporated  under the laws of the United States of America
or a state  thereof,  it shall  deliver to the Borrower  and the  Administrative
Agent  certification as to exemption from deduction or withholding of any United
States federal income taxes in accordance with Section 8.04.

          (d) Any Bank may at any time  assign all or any  portion of its rights
under this Agreement and its Note to a Federal  Reserve Bank. No such assignment
shall release the transferor Bank from its obligations hereunder.

          (e) No Assignee,  Participant or other transferee of any Bank's rights
shall be entitled to receive any greater payment under Section 8.03 or 8.04 than
such Bank  would  have been  entitled  to  receive  with  respect  to the rights
transferred,  unless such  transfer is made with the  Borrower's  prior  written
consent or by reason of the  provisions of Section 8.02,  8.03 or 8.04 requiring
such Bank to  designate a different  Applicable  Lending  Office  under  certain
circumstances  or at a time when the  circumstances  giving rise to such greater
payment did not exist.

          (f) Each Bank shall,  upon receipt from a Shareholder  Guarantor of an
amount  equal to all of such Bank's  Guaranteed  Obligations  (as defined in the
relevant  Shareholder  Guaranty)  (the  "Transfer  Payment"),   assign  to  such
Shareholder  Guarantor the  corresponding  portion of its rights and obligations
under this  Agreement  and the Notes in  accordance  with  paragraph (c) of this
Section   9.06;   provided  that  (i)  the  consent  of  the  Borrower  and  the
Administrative  Agent shall not be required for such assignment and (ii) no such
assignment  shall be effective until each Bank has received its Transfer Payment
from the applicable Shareholder Guarantor.




                                       66

<PAGE>




          SECTION 9.07.  Collateral.  Each of the Banks represents to the Agents
and  each of the  other  Banks  that it in good  faith is not  relying  upon any
"margin  stock" (as defined in  Regulation  U) as collateral in the extension or
maintenance of the credit provided for in this Agreement.

         SECTION 9.08. Governing Law; Submission to Jurisdiction. This Agreement
and each Note shall be governed by and construed in accordance  with the laws of
the  State  of New  York.  The  Borrower  hereby  submits  to  the  nonexclusive
jurisdiction  of the United States  District Court for the Southern  District of
New York and of any New York State court  sitting in New York City for  purposes
of all legal  proceedings  arising out of or relating to this  Agreement  or the
transactions  contemplated  hereby.  The  Borrower  irrevocably  waives,  to the
fullest  extent  permitted by law, any  objection  which it may now or hereafter
have to the laying of the venue of any such  proceeding  brought in such a court
and any claim that any such proceeding  brought in such a court has been brought
in an inconvenient forum.

         SECTION 9.09. Counterparts;  Integration; Effectiveness. This Agreement
may be signed in any number of counterparts, each of which shall be an original,
with the same effect as if the signatures  thereto and hereto were upon the same
instrument.  This Agreement  constitutes the entire agreement and  understanding
among  the  parties  hereto  and  supersedes  any and all prior  agreements  and
understandings,  oral or written,  relating to the subject matter  hereof.  This
Agreement  shall become  effective  upon receipt by the  Documentation  Agent of
counterparts hereof signed by each of the parties hereto (or, in the case of any
party as to which an executed counterpart shall not have been received,  receipt
by the  Documentation  Agent in form  satisfactory to it of telegraphic,  telex,
facsimile  or other  written  confirmation  from such  party of  execution  of a
counterpart hereof by such party).

          SECTION 9.10. Waiver of Jury Trial.  EACH OF THE BORROWER,  THE AGENTS
AND THE BANKS  HEREBY  IRREVOCABLY  WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN
ANY  LEGAL  PROCEEDING  ARISING  OUT OF OR  RELATING  TO THIS  AGREEMENT  OR THE
TRANSACTIONS CONTEMPLATED HEREBY.

         SECTION  9.11.  Confidentiality.  Each Bank  agrees to take  normal and
reasonable  precautions and exercise due care to maintain the confidentiality of
all  non-public  information  provided  to it by  the  Borrower  or  any  of its
Subsidiaries  by the Agents on the  Borrower's  or such  Subsidiary's  behalf in
connection with this Agreement or any other Loan Document and neither it nor any
of its  Affiliates  shall use any such  information  for any  purpose  or in any





                                       67

<PAGE>


manner other than pursuant to the terms  contemplated by this Agreement,  except
to the extent such  information  (a) was or becomes  generally  available to the
public other than as a result of a disclosure by the Bank, or (b) was or becomes
available on a  non-confidential  basis from a source  other than the  Borrower,
provided that such source is not bound by a  confidentiality  agreement with the
Borrower known to the Bank; provided,  further,  that any Bank may disclose such
information  (A) to any other Bank or to the  Agents,  (B) at the request of any
regulatory  authority or in connection  with an  examination of such Bank by any
such  authority;  (C)  pursuant to subpoena  or other  court  process;  (D) when
required to do so in accordance  with the provisions of any applicable  law; (E)
at the express  direction of any other agency of any State of the United  States
of  America  or of any  other  jurisdiction  in which  such  Bank  conducts  its
business;  and  (F) to such  Bank's  independent  auditors  and  legal  counsel.
Notwithstanding  the foregoing,  the Company authorizes each Bank to disclose to
any  Participant  or  Assignee  (each,  a  "Transferee")   and  any  prospective
Transferee  such  financial  and other  information  in such  Bank's  possession
concerning the Borrower or any of its  Subsidiaries  which has been delivered to
the Banks pursuant to this Agreement or which has been delivered to the Banks by
the Borrower or any of its  Subsidiaries  in  connection  with the Banks' credit
evaluation  of the Borrower  and its  Subsidiaries  prior to entering  into this
Agreement;  provided that such Transferee agrees in writing to such Bank to keep
such  information  confidential  to  the  same  extent  required  of  the  Banks
hereunder.




                                       68

<PAGE>



         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly  executed by their  respective  authorized  officers as of the day and year
first above written.

                             AMERICAN MOBILE SATELLITE
                             CORPORATION


                             By  /s/Gary M. Parsons
                                 ------------------

                             Name:      Gary M. Parsons
                             Title:     President and Chief
                                        Executive Officer
                             Address:   10802 Parkridge Boulevard
                                        Reston, VA 20191
                             Attention: General Counsel
                             Facsimile: 703-758-6134




                                       69

<PAGE>



                             TORONTO DOMINION (TEXAS), INC.


                             By  /s/Jano Mott
                                 ------------
                             Name:      Jano Mott      
                             Title:     Vice President


                             MORGAN GUARANTY TRUST
                             COMPANY OF NEW YORK


                             By   /s/John M. Mikolay
                                  ------------------
                             Name:      John M. Mikolay
                             Title:     Vice President


                             BANK OF AMERICA NATIONAL
                             TRUST AND SAVINGS
                             ASSOCIATION


                             By    /s/Robert W. Troutman
                                   ---------------------
                             Name:      Robert W. Troutman
                             Title:     Managing Director






                                       70

<PAGE>



                             MORGAN GUARANTY TRUST
                             COMPANY OF NEW YORK, as
                             Documentation Agent


                             By   /s/John M. Mikolay
                                  ------------------
                             Name:      John M. Mikolay
                             Title:     Vice President
                             Address:   500 Stanton Christiana Road
                                        Newark, DE 19713
                             Attention: Victoria Fedele
                                        Facsimile: 302-634-1852


                             TORONTO DOMINION (TEXAS),
                             INC., as Administrative Agent


                             By  /s/Jano Mott
                                 ------------
                             Name:      Jano Mott      
                             Title:     Vice President
                             Address:   909 Fannin Street
                                        Houston, TX 77010
                             Attention: Jano Mott
                             Facsimile: 713-951-9921




                                       71

<PAGE>

<TABLE>
<CAPTION>


                               COMMITMENT SCHEDULE


              Bank               Tranche A        Tranche B        Tranche C
                                 Commitment       Commitment       Commitment
<S>                             <C>              <C>               <C>       
Toronto Dominion (Texas),       $37,500,000               $0       $6,250,000
Inc.
Morgan Guaranty Trust            37,500,000               $0       $6,250,000
Company of New York
Bank of America National                 $0      $12,500,000               $0
Trust and Savings
Association

</TABLE>




                                                1

<PAGE>



                                PRICING SCHEDULE

         "Euro-Dollar Margin" means for any date the rate set forth below in the
column corresponding to the "Pricing Level" that applies at such date:



                        Level I       Level II         Level III
Euro-Dollar Margin       0.50%          0.75%             1.00%
- -------------------   -----------   -------------     ------------


         For purposes of this Schedule,  the following  terms have the following
meanings:

         "Level I  Pricing"  applies  at any date if, as of such  date,  Hughes'
long-term debt is rated A3 or higher by Moody's and A- or higher by S&P

         "Level II Pricing" applies at any date if, as of such date, (i) Hughes'
long-term  debt is rated Baa2 or higher by Moody's  and BBB or higher by S&P and
(ii) Level I Pricing does not apply.

         "Level III Pricing" applies at any date if neither Level I nor Level II
Pricing applies.

         "Moody's" means Moody's Investors Service, Inc.

         "Pricing Level" refers to the  determination of which of Level I, Level
II or Level III applies at any date.

         "S&P" means Standard & Poor's Rating Service.

         The credit  ratings to be utilized  for  purposes of this  Schedule are
those  assigned to the senior  unsecured  long-term  debt  securities  of Hughes
without  third-party  credit  enhancement,  and any rating assigned to any other
debt security of Hughes shall be disregarded.  The ratings in effect for any day
are those in effect at the close of business on such day.




                                        1

<PAGE>



                               DISCLOSURE SCHEDULE


Section 1.01 -- FCC Licenses.



Section 4.03 -- Government Approvals.



Section 4.05 -- Litigation.



Section 4.07 -- Plans.



Section 4.10(c) -- Material Adverse Effect.



Section 4.13 -- Subsidiaries and Equity Investments.



Section 5.17 -- Existing Liens.



Section 5.25 -- Existing Indebtedness.




                                        1

<PAGE>



                                                           EXHIBIT A -- Note



                                    TERM NOTE
                                                           New York, New York
                                                           [DATE]

         For value received,  American Mobile Satellite Corporation,  a Delaware
corporation   (the   "Borrower"),    promises   to   pay   to   the   order   of
______________________  (the "Bank"),  for the account of its Applicable Lending
Office,  the  unpaid  principal  amount  of each  Loan  made by the  Bank to the
Borrower pursuant to the Term Credit Agreement referred to below on the maturity
date  provided for in the Term Credit  Agreement.  The Borrower  promises to pay
interest  on the unpaid  principal  amount of each such Loan on the dates and at
the rate or rates provided for in the Term Credit  Agreement.  All such payments
of principal and interest  shall be made in lawful money of the United States in
Federal   or  other   immediately   available   funds  at  the   office  of  The
Toronto-Dominion Bank, 31 West 52nd Street, New York, New York.

         All Loans  made by the  Bank,  the  respective  Types  thereof  and all
repayments  of the  principal  thereof shall be recorded by the Bank and, if the
Bank  so  elects  in  connection  with  any  transfer  or  enforcement   hereof,
appropriate notations to evidence the foregoing information with respect to each
such Loan then outstanding may be endorsed by the Bank on the schedule  attached
hereto,  or on a  continuation  of such  schedule  attached  to and  made a part
hereof;  provided that the failure of the Bank to make any such  recordation  or
endorsement shall not affect the obligations of the Borrower  hereunder or under
the Term Credit Agreement.

         This note is one of the Notes referred to in the Term Credit  Agreement
dated as of March 31, 1998 among  American  Mobile  Satellite  Corporation,  the
banks party thereto, Morgan Guaranty Trust Company of New York, as Documentation
Agent and Toronto Dominion (Texas),  Inc. as  Administrative  Agent (as the same
may be amended from time to time, the "Term Credit Agreement"). Terms defined in
the Term Credit  Agreement are used herein with the same meanings.  Reference is
made to the Term Credit  Agreement for provisions for the prepayment  hereof and
the acceleration of the maturity hereof.



                            AMERICAN MOBILE SATELLITE
                            CORPORATION



                             By  ----------------------------------------------

                             Name:
                             Title:




                                        1

<PAGE>




                         LOANS AND PAYMENTS OF PRINCIPAL

- -------------------------------------------------------------------------
                  Amount          Type           Amount of
                      of           of            Principal       Notation
Date                Loan          Loan             Repaid         Made By
- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------




                                        3

<PAGE>



                                EXHIBIT B -- Opinion of Counsel for the Borrower

                                   OPINION OF
                            COUNSEL FOR THE BORROWER



                                                              March __, 1998


To the Banks, Shareholder Guarantors and the Agents
Referred to Below
c/o Morgan Guaranty Trust Company
of New York, as Documentation Agent
60 Wall Street
New York, New York  10260

Dear Sirs:

         I am Vice  President,  Secretary and General Counsel of American Mobile
Satellite Corporation,  a Delaware corporation ("AMSC"). In such capacity I have
become familiar with the  $100,000,000  Term Credit  Agreement (the "Term Credit
Agreement")  dated as of March 31,  1998  among  AMSC,  the banks  listed on the
signature  pages  thereof,  Morgan  Guaranty  Trust  Company  of  New  York,  as
Documentation  Agent,  and Toronto  Dominion  (Texas),  Inc., as  Administrative
Agent.  Capitalized  terms not otherwise  defined herein shall have the meanings
set forth in the Term Credit  Agreement.  This opinion is being  rendered to you
pursuant to Section 3.1(a) of the Term Credit Agreement.

         In rendering this opinion, I have examined originals or copies of:

1.       the  Term  Credit  Agreement,  the  Notes  and  the Security and Pledge
         Agreement (collectively, the "Loan Documents");

2.       the certificate of incorporation, as amended, of AMSC;

3.       the bylaws, as amended, of AMSC;

4.       the  Certificate  of Good  Standing  with respect to AMSC issued by the
         Secretary  of State of the State of Delaware not earlier than March 20,
         1998;




                                        1

<PAGE>



5.       the Certificate of Good Standing as a Foreign  Corporation with respect
         to AMSC issued by the State Corporation  Commission of the Commonwealth
         of Virginia dated March 20, 1998; and

6.       certain  resolutions  adopted  by the Board of  Directors  of AMSC at a
         meeting of the Board held on March 19, 1998;

upon all of which I have relied. I have not  independently  verified any factual
matters in connection with or apart from my review of the documents  referred to
above and,  accordingly,  I do not express any opinion as to matters  that might
have been disclosed by independent verification.

         In arriving at the opinions  expressed  below, I have assumed,  and not
verified, the authenticity of all documents submitted to me as originals and the
conformity to original documents of all documents  submitted to me as copies, as
well as the due and valid  authorization,  execution  and  delivery  of all such
documents by the appropriate party or parties (other than the Loan Parties), and
that each such party  (other than the  applicable  Loan  Parties)  has  adequate
power,  authority and legal right to enter into such  documents to which it is a
party and to  perform  its  obligations  under such  documents  to which it is a
party.

         Based solely upon the foregoing and in reliance thereon, and subject to
the  qualifications,  limitations  and  assumptions  set forth herein,  it is my
opinion that:

         1. AMSC is a corporation  duly  incorporated,  validly  existing and in
good  standing  under the laws of  Delaware,  has all  corporate  powers and all
material governmental licenses, authorizations,  consents and approvals required
to carry on its business as now  conducted,  and is duly  qualified as a foreign
corporation,  licensed and in good standing under the laws of each  jurisdiction
where its  ownership,  lease or  operation  of  property  or the  conduct of its
business require such qualification  except where the failure to be so qualified
would not reasonably be expected to result in a Material Adverse Effect.

         2. The execution,  delivery and  performance by AMSC of the Term Credit
Agreement,  the Notes and each other  Loan  Document  are  within its  corporate
powers,  have been duly authorized by all necessary  corporate action and do not
and will not: (a)  contravene  the terms of its  certificate  of  incorporation,
bylaws  or other  organization  documents;  (b)  conflict  with or result in any
breach or  contravention  of, or the creation of any Lien under,  any indenture,
agreement, lease, instrument,  Contractual Obligation, injunction, order, decree
or  undertaking  to which such  Person is a party  (other  than Liens  under the
Security and Pledge Agreement); or (c) violate any Requirement of Law.




                                        2

<PAGE>



         3.  Each  Loan  Document  constitutes  the  legal,  valid  and  binding
obligations or agreements of AMSC, enforceable against it in accordance with its
terms.

         4. Except as set forth in Section 4.05 of the  Disclosure  Schedule and
for matters  arising  after the  Effective  Date which could not  reasonably  be
expected  to have a  Material  Adverse  Effect,  there  are no  actions,  suits,
proceedings,  claims  or  disputes  pending,  or to the  best of our  knowledge,
threatened  or  contemplated  at law, in equity,  in  arbitration  or before any
Governmental Authority,  against AMSC or any of its Subsidiaries or any of their
respective  properties  which:  (a)  purport  to affect or  pertain  to any Loan
Document, or any of the transactions  contemplated thereby; or (b) if determined
adversely  to AMSC or any of its  Subsidiaries,  could have a  Material  Adverse
Effect.  No injunction,  writ,  temporary  restraining order or any order of any
nature has been issued by any court or other Governmental  Authority  purporting
to enjoin or  restrain  the  execution,  delivery  and  performance  of any Loan
Document,  or  directing  that the  transactions  provided  for  therein  not be
consummated as therein provided.

         5.  None of  AMSC,  any  Person  controlling  AMSC,  or any  Subsidiary
thereof,  is (a) an  "Investment  Company"  within the meaning of the Investment
Company  Act of 1940;  or (b)  subject to  regulation  under the Public  Utility
Holding Company Act of 1935, or, to the best of our knowledge, the Federal Power
Act, the Interstate  Commerce Act, any state public  utilities code or any other
Federal  or  state  statute  or   regulation   limiting  its  ability  to  incur
Indebtedness.

         6.  Assuming  the Agents and the Banks have no knowledge of any adverse
claim thereto,  the Security and Pledge Agreement,  together with possession and
retention  in the  State  of New  York  by the  Administrative  Agent  of  stock
certificates evidencing the Pledged Stock (as defined in the Security and Pledge
Agreement),  together with the related duly executed and completed stock powers,
creates a valid and perfected  security  interest in the Pledged Stock under the
New York Uniform  Commercial Code in favor of the  Administrative  Agent for the
benefit  of  the  Secured  Parties  (as  defined  in  the  Security  and  Pledge
Agreement),  subject to the following:  the perfection and the  continuation  of
perfection  of the  Administrative  Agent's  security  interest  in  proceeds is
limited  to the  extent  set  forth in  Section  9-306  of the New York  Uniform
Commercial Code.

         7. The Security and Pledge  Agreement is in  acceptable  legal form for
the creation of enforceable security interests under the Uniform Commercial Code
of the  State of New York.  The  financing  statements  attached  hereto  are in
appropriate form for filing with the filing offices  specified  thereon.  To the
extent that a security  interest in the  Collateral  (as defined in the Security
and Pledge  Agreement) may be perfected by the filing of a financing  statement,
the security  interest in such  Collateral  will be perfected upon the filing of
such financing statements in such filing offices.




                                        3

<PAGE>



         The opinions  set forth in this  paragraph 7 are subject to the further
qualification  that I express no opinion as to (i) AMSC's  rights in or title to
any Collateral;  and (ii) the priority of the  Administrative  Agent's  security
interest in the Collateral, and the opinions set forth in paragraphs 6 and 7 are
subject  to the  further  qualification  that I express no opinion as to (i) the
enforceability  of  provisions  in  the  Security  and  Pledge  Agreement  as to
self-help and non-judicial remedies, (ii) whether the procedures relating to the
sale or disposition of the Collateral in the Security and Pledge Agreement would
meet applicable  requirements  for a commercially  reasonable  disposition,  and
(iii) the  enforceability of the provisions in the Security and Pledge Agreement
relating to or purporting to limit the Administrative  Agent's duty with respect
to the Collateral.

         The  foregoing  opinions are subject to the following  assumptions  and
qualifications:

         (a) The  opinions set forth in paragraph 3 are subject to the effect of
any applicable  bankruptcy,  insolvency,  reorganization,  moratorium or similar
laws  affecting  creditors'  rights  generally  and  to  the  possible  judicial
application of foreign laws or governmental  action affecting the enforcement of
creditors' rights.

         (b) The  opinions  set forth in  paragraph 3 are subject to the further
qualification  that the enforceability of the obligations of AMSC under the Loan
Documents  are subject to general  principles of equity  (regardless  of whether
such  enforceability  is considered  in a proceeding in equity or at law).  Such
principles  of  equity  are  of  general   application  and,  in  applying  such
principles,  a  court,  among  other  things,  might  not  allow a  creditor  to
accelerate  the  maturity  of a debt upon the  occurrence  of a  default  deemed
immaterial  or might  decline  to  order  that a  covenant  be  performed.  Such
principles  applied by a court might include,  among other things, a requirement
that creditors act with  reasonableness and good faith. Such a requirement might
be applied,  among other  situations,  to the  provisions  of any Loan  Document
requiring  the payment of an indemnity or  compensation  to any party thereto or
purporting to authorize conclusive determinations by any party thereto.

         (c) With  respect  to my opinion in  paragraph  3 hereof,  I express no
opinion as to whether the courts of a  jurisdiction  other than the State of New
York would give effect to the choice of New York law as governing the agreements
as to which I express an opinion in paragraph 3.

         (d) The foregoing  opinions are limited to the laws of the State of New
York,  the General  Corporation  Law of the State of  Delaware,  the laws of the
Commonwealth  of Virginia  and the Federal law of the United  States  (except as
noted below),  and I do not express any opinion herein  concerning any other law
(including,  without limitation,  any such other law of any jurisdiction wherein





                                        4

<PAGE>


any party to any of Loan  Document  may be located or deemed  located or wherein
enforcement of any such  documents may be sought).  I do not express any opinion
as to any matters arising under the Communications  Act of 1934, as amended,  or
any rules or  regulations  of the Federal  Communications  Commission.  I do not
express  any  opinion  as to  any  matters  (including  Governmental  Approvals)
relating  to  international  law,  including  compliance  by any Loan Party with
treaties  involving  the  International  Maritime  Satellite  Organization,  the
International  Telecommunications  Satellite  Organization and the International
Telecommunication  Union.  I am not a member of the Bar of the State of Delaware
and insofar as the opinions  expressed  herein  relate to matters of the General
Corporation  Law of the State of Delaware,  I have relied on the latest standard
compilations of statutes available to me.

         The opinions herein are rendered as of the date of this opinion,  and I
assume no obligation to revise or supplement this opinion at any date subsequent
hereto.

         The opinions  set forth above relate  solely to the matters as to which
my opinion has been  requested  by you,  and you must judge  whether the matters
addressed herein are sufficient for your purposes.  I do not express any opinion
as to any other matters.

         This opinion is rendered to the  Documentation  Agent and is solely for
its benefit, for the benefit of the Shareholder Guarantors,  and for the benefit
of any Bank party to the Term  Credit  Agreement  in  connection  with the above
transaction.  This opinion may not be relied upon by the Documentation Agent for
any other purpose, or furnished to, quoted to or relied upon by any other Person
other than any Bank or  Shareholder  Guarantor  referred  to in the  immediately
preceding sentence,  for any purpose without my prior written consent. It is not
to be filed with or furnished to any  Governmental  Authority or other Person in
either case without my prior written consent.

                                             Very truly yours,


                                             /s/Randy S. Segal
                                             Randy S. Segal
                                             General Counsel





                                        5

<PAGE>



             EXHIBIT C -- Opinion of Special Counsel for the Agents


                                   OPINION OF
                             DAVIS POLK & WARDWELL,
                         SPECIAL COUNSEL FOR THE AGENTS


                                                     March __, 1998


To the Banks and the Agents
Referred to Below
c/o Morgan Guaranty Trust Company
of New York, as Documentation Agent
60 Wall Street
New York, New York  10260

Dear Sirs:

         We have participated in the preparation of the $100,000,000 Term Credit
Agreement  (the  "Term  Credit  Agreement")  dated as of March  31,  1998  among
American Mobile Satellite  Corporation,  a Delaware  corporation  ("AMSC"),  the
banks listed on the signature pages thereof (the "Banks"), Morgan Guaranty Trust
Company of New York, as Documentation Agent, and Toronto Dominion (Texas), Inc.,
as Administrative Agent (collectively,  the "Agents"), and have acted as special
counsel for the Agents for the purpose of  rendering  this  opinion  pursuant to
Section  3.01 of the Term  Credit  Agreement.  Terms  defined in the Term Credit
Agreement are used herein as therein defined.

         We have examined originals or copies, certified or otherwise identified
to our  satisfaction,  of such  documents,  corporate  records,  certificates of
public   officials  and  other   instruments   and  have  conducted  such  other
investigations  of fact and law as we have deemed  necessary  or  advisable  for
purposes of this opinion.

         Upon the basis of the  foregoing,  we are of the opinion that  assuming
that  the  execution,  delivery  and  performance  by  AMSC of the  Term  Credit
Agreement  and the Notes are  within  its  corporate  powers  and have been duly
authorized  by  all  necessary  corporate  action,  the  Term  Credit  Agreement
constitutes  a valid and binding  agreement of AMSC and each Note  constitutes a
valid and binding  obligation  of AMSC, in each case  enforceable  in accordance





                                        1

<PAGE>


with its terms  except as may be limited by  bankruptcy,  insolvency  or similar
laws affecting creditors' rights generally and by general principles of equity.

         We are  members  of the Bar of the State of New York and the  foregoing
opinion is limited to the laws of the State of New York. In giving the foregoing
opinion,  we  express  no  opinion  as to the  effect (if any) of any law of any
jurisdiction  (except the State of New York) in which any Bank is located  which
limits the rate of interest that such Bank may charge or collect.

         This  opinion is rendered  solely to you in  connection  with the above
matter.  This  opinion  may not be relied  upon by you for any other  purpose or
relied upon by any other person without our prior written consent.

                                Very truly yours,




                                        2

<PAGE>



                EXHIBIT D -- Assignment and Assumption Agreement



                       ASSIGNMENT AND ASSUMPTION AGREEMENT

         AGREEMENT  dated as of  _________,  19__ among [NAME OF ASSIGNOR]  (the
"Assignor"),  [NAME OF ASSIGNEE] (the  "Assignee"),  AMERICAN  MOBILE  SATELLITE
CORPORATION   (the   "Borrower")  and  TORONTO   DOMINION   (TEXAS),   INC.,  as
Administrative Agent (the "Agent").

         WHEREAS,  this  Assignment and Assumption  Agreement (the  "Agreement")
relates to the  $100,000,000  Term Credit  Agreement  dated as of March 31, 1998
among the Borrower,  the Assignor and the other Banks party  thereto,  as Banks,
Morgan Guaranty Trust Company of New York, as Documentation Agent, and the Agent
(the "Credit Agreement");

         WHEREAS,  Loans made to the Borrower by the  Assignor  under the Credit
Agreement in the aggregate  principal  amount of $__________  are outstanding at
the date hereof; and

         WHEREAS,  the  Assignor  proposes to assign to the  Assignee all of the
rights of the Assignor under the Credit Agreement in respect of a portion of its
outstanding  Loans in a principal  amount equal to  $__________  (the  "Assigned
Amount"),  and the  Assignee  proposes to accept  assignment  of such rights and
assume the corresponding obligations from the Assignor on such terms;

         NOW,  THEREFORE,  in  consideration  of the  foregoing  and the  mutual
agreements contained herein, the parties hereto agree as follows:

         1.  Definitions.  All capitalized  terms not otherwise  defined herein
shall have the respective meanings set forth in the Credit Agreement.

         2.  Assignment.  The Assignor  hereby assigns and sells to the Assignee
all of the rights of the  Assignor  under the Credit  Agreement to the extent of
the Assigned  Amount,  and the Assignee  hereby accepts such assignment from the
Assignor and assumes all of the  obligations  of the  Assignor  under the Credit
Agreement to the extent of the Assigned Amount,  including the purchase from the
Assignor of the corresponding  portion of the principal amount of the Loans made
by the Assignor  outstanding at the date hereof. Upon the execution and delivery
hereof by the  Assignor,  the  Assignee,  [the  Borrower  and the Agent] and the





                                        1

<PAGE>


payment of the  amounts  specified  in Section 3 required to be paid on the date
hereof (i) the Assignee shall, as of the date hereof,  succeed to the rights and
be obligated  to perform the  obligations  of a Bank under the Credit  Agreement
with a  Commitment  in an  amount  equal to the  Assigned  Amount,  and (ii) the
Commitment of the Assignor  shall,  as of the date hereof,  be reduced by a like
amount and the Assignor released from its obligations under the Credit Agreement
to the extent such obligations have been assumed by the Assignee. The assignment
provided for herein shall be without recourse to the Assignor.

         3. Payments.  As consideration for the assignment and sale contemplated
in Section 2 hereof,  the Assignee  shall pay to the Assignor on the date hereof
in Federal funds the amount  heretofore  agreed  between them.1 It is understood
that  commitment  and/or  facility  fees  accrued to the date hereof are for the
account of the  Assignor  and such fees  accruing  from and  including  the date
hereof  are for the  account  of the  Assignee.  Each  of the  Assignor  and the
Assignee hereby agrees that if it receives any amount under the Credit Agreement
which is for the account of the other party  hereto,  it shall  receive the same
for the account of such other party to the extent of such other party's interest
therein and shall promptly pay the same to such other party.

         [4.  Consent  of  the  Borrower  and  the  Agent.   This  Agreement  is
conditioned  upon the consent of the Borrower and the Agents pursuant to Section
9.06 of the Credit  Agreement.  The execution of this  Agreement by the Borrower
and the Agents is  evidence  of this  consent.  Pursuant  to Section  2.03,  the
Borrower  agrees  to  execute  and  deliver a Note  payable  to the order of the
Assignee to evidence the assignment and assumption provided for herein.]

         5.  Non-Reliance on Assignor.  The Assignor makes no  representation or
warranty in connection with, and shall have no  responsibility  with respect to,
the  solvency,  financial  condition,  or  statements  of  the  Borrower  or the
Borrower,  or the validity and enforceability of the obligations of the Borrower
in respect of the Credit Agreement or any Note. The Assignee  acknowledges  that
it has,  independently  and without reliance on the Assignor,  and based on such
documents  and  information  as it has deemed  appropriate,  made its own credit
analysis  and  decision  to enter into this  Agreement  and will  continue to be
responsible  for making its own independent  appraisal of the business,  affairs
and financial condition of the Borrower.
- --------
         1 Amount should combine  principal  together with accrued  interest and
breakage compensation, if any, to be paid by the Assignee, net of any portion of
any upfront fee to be paid by the Assignor to the Assignee. It may be preferable
in an appropriate case to specify these amounts generically or by formula rather
than as a fixed sum.




                                        2

<PAGE>



         6. Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of New York.

         7.  Counterparts.  This  Agreement  may  be  signed  in any  number  of
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto and hereto were upon the same instrument.

         IN WITNESS  WHEREOF,  the  parties  have caused  this  Agreement  to be
executed and  delivered by their duly  authorized  officers as of the date first
above written.

                               [NAME OF ASSIGNOR]


                               By   --------------------------------------------

                               Name:
                               Title:


                               [NAME OF ASSIGNEE]


                               By   --------------------------------------------

                               Name:
                               Title:


                               AMERICAN MOBILE SATELLITE
                               CORPORATION


                               By   --------------------------------------------

                               Name:
                               Title:


                               TORONTO DOMINION (TEXAS), INC.,
                               as Administrative Agent


                               By   --------------------------------------------

                               Name:
                               Title:

                                        3









<PAGE>



                                                                 EXHIBIT 10.73

                                                                [EXECUTION COPY]





                                  $100,000,000


                           REVOLVING CREDIT AGREEMENT


                                   dated as of


                                 March 31, 1998



                                      among


                         AMSC Acquisition Company, Inc.,


                     American Mobile Satellite Corporation,


                            The Banks Listed Herein,


                   Morgan Guaranty Trust Company of New York,
                             as Documentation Agent,


                                       and


                         Toronto Dominion (Texas), Inc.,
                             as Administrative Agent





<PAGE>


                                                                         PAGE

                                TABLE OF CONTENTS

                             ----------------------

                                                                         PAGE

                                    ARTICLE 1
                                   DEFINITIONS

SECTION 1.01.  Definitions..................................................1
SECTION 1.02.  Accounting Terms and Determinations.........................21

                                    ARTICLE 2
                                   THE CREDITS

SECTION 2.01.  Commitments to Lend.........................................21
SECTION 2.02.  Method of Borrowing.........................................21
SECTION 2.03.  Notes.......................................................23
SECTION 2.04.  Maturity of Loans...........................................24
SECTION 2.05.  Interest Rates..............................................24
SECTION 2.06.  Commitment Fees.............................................25
SECTION 2.07.  Optional Termination or Reduction of Commitments............26
SECTION 2.08.  Method of Electing Interest Rates...........................26
SECTION 2.09.  Mandatory Termination and Reduction of Commitments..........28
SECTION 2.10.  Optional Prepayments........................................29
SECTION 2.11.  General Provisions as to Payments...........................29
SECTION 2.12.  Funding Losses..............................................30
SECTION 2.13.  Computation of Interest and Fees............................30

                                    ARTICLE 3
                                   CONDITIONS

SECTION 3.01.  Closing.....................................................31
SECTION 3.02.  Borrowings..................................................33

                                    ARTICLE 4
                         REPRESENTATIONS AND WARRANTIES

SECTION 4.01.  Corporate Existence and Power...............................34
SECTION 4.02.  Corporate Authorization; No Contravention...................34
SECTION 4.03.  Government Approvals........................................34
SECTION 4.04.  Binding Effect..............................................35
SECTION 4.05.  Litigation..................................................35
SECTION 4.06.  No Default..................................................35
SECTION 4.07.  ERISA Compliance............................................36



                                        i

<PAGE>


                                                                         PAGE

SECTION 4.08.  Title to Property...........................................37
SECTION 4.09.  Taxes.......................................................37
SECTION 4.10.  Financial Condition.........................................37
SECTION 4.11.  Environmental Matters.......................................38
SECTION 4.12.  Regulated Entities..........................................38
SECTION 4.13.  Subsidiaries................................................39
SECTION 4.14.  Insurance...................................................39
SECTION 4.15.  Business....................................................39
SECTION 4.16.  Disclosure..................................................39

                                    ARTICLE 5
                                    COVENANTS

SECTION 5.01.  Information.................................................40
SECTION 5.02.  Certificates; Other Information.............................40
SECTION 5.03.  Notices.....................................................41
SECTION 5.04.  Conduct of Business; Preservation of Corporate Existence....43
SECTION 5.05.  Maintenance of Property.....................................43
SECTION 5.06.  Maintenance of Insurance....................................43
SECTION 5.07.  Payment of Obligations......................................47
SECTION 5.08.  Compliance with Laws........................................47
SECTION 5.09.  Inspection of Property and Books and Records................47
SECTION 5.10.  Environmental Laws..........................................48
SECTION 5.11.  Use of Proceeds.............................................48
SECTION 5.12.  No Subsidiaries.............................................48
SECTION 5.13.  Government Approvals........................................48
SECTION 5.14.  Further Assurances..........................................48
SECTION 5.15.  Limitation on Liens.........................................49
SECTION 5.16.  Disposition of Assets, Consolidations and Mergers...........50
SECTION 5.17.  Employee Contracts and Arrangements.........................52
SECTION 5.18.  Investments.................................................52
SECTION 5.19.  Transactions with Affiliates................................52
SECTION 5.20.  Compliance with ERISA.......................................52
SECTION 5.21.  Restricted Payments.........................................53
SECTION 5.22.  Accounting Changes..........................................53
SECTION 5.23.  Limitation on Indebtedness..................................53




                                       ii

<PAGE>


                                                                         PAGE

                                    ARTICLE 6
                                    DEFAULTS

SECTION 6.01.  Events of Default...........................................54
SECTION 6.02.  Notice of Default...........................................59

                                    ARTICLE 7
                                   THE AGENTS

SECTION 7.01.  Appointment and Authorization...............................59
SECTION 7.02.  Agents and Affiliates.......................................59
SECTION 7.03.  Action by Agents............................................59
SECTION 7.04.  Consultation with Experts...................................59
SECTION 7.05.  Liability of Agents.........................................59
SECTION 7.06.  Indemnification.............................................60
SECTION 7.07.  Credit Decision.............................................60
SECTION 7.08.  Successor Agent.............................................60
SECTION 7.09.  Agents' Fees................................................61

                                    ARTICLE 8
                             CHANGE IN CIRCUMSTANCES

SECTION 8.01.  Basis for Determining Interest Rate Inadequate or Unfair....61
SECTION 8.02.  Illegality..................................................61
SECTION 8.03.  Increased Cost and Reduced Return...........................62
SECTION 8.04.  Taxes.......................................................64
SECTION 8.05.  Base Rate Loans Substituted for Affected Euro-Dollar
               Loans.......................................................65

                                    ARTICLE 9
                                 PARENT GUARANTY

SECTION 9.01.  The Parent Guaranty.........................................66
SECTION 9.02.  Guaranty Unconditional......................................66
SECTION 9.03.  Discharge Only Upon Payment in Full; Restatement in
               Certain Circumstances.......................................67
SECTION 9.04.  Waiver by the Parent Guarantor..............................67
SECTION 9.05.  Subrogation.................................................68
SECTION 9.06.  Stay of Acceleration........................................68
SECTION 9.07.  Subordination...............................................68




                                       iii

<PAGE>


                                                                          PAGE

                                   ARTICLE 10
                                  MISCELLANEOUS

SECTION 10.01.  Notices.....................................................70
SECTION 10.02.  No Waivers..................................................70
SECTION 10.03.  Expenses; Indemnification...................................71
SECTION 10.04.  Sharing of Set-offs.........................................71
SECTION 10.05.  Amendments and Waivers......................................72
SECTION 10.06.  Successors and Assigns......................................72
SECTION 10.07.  Collateral..................................................74
SECTION 10.08.  Governing Law; Submission to Jurisdiction...................74
SECTION 10.09.  Counterparts; Integration; Effectiveness....................74
SECTION 10.10.  Waiver of Jury Trial........................................75
SECTION 10.11.  Confidentiality.............................................75

COMMITMENT SCHEDULE
PRICING SCHEDULE
DISCLOSURE SCHEDULE
EXHIBIT A - Note
EXHIBIT B - Opinion of Counsel for the Parent Guarantor and the Borrower 
EXHIBIT C - Opinion  of  Special  Counsel  for the  Agents  
EXHIBIT D -  Assignment  and Assumption Agreement 
EXHIBIT E - Subsidiary Guaranty





                                       iv

<PAGE>



                           REVOLVING CREDIT AGREEMENT


     AGREEMENT dated as of March 31, 1998 among AMSC ACQUISITION COMPANY,  INC.,
AMERICAN MOBILE SATELLITE  CORPORATION,  the BANKS listed on the signature pages
hereof,  MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Documentation  Agent, and
TORONTO DOMINION (TEXAS), INC., as Administrative Agent.

     The parties hereto agree as follows:



                                    ARTICLE 1
                                   DEFINITIONS

     SECTION 1.01.  Definitions.  The following terms, as used herein,  have the
following meanings:

     "ACTEL" means African Continental Telecommunications Ltd.

     "ACTEL  Agreement"  means the agreement among AMSC Subsidiary  Corporation,
the Parent Guarantor and ACTEL, dated as of December 2, 1997,  pursuant to which
the  Borrower  will lease its  MSAT-2  satellite  to ACTEL,  as in effect on the
Effective Date.

     "Acquisition"  means the acquisition by the Borrower of 100% of the capital
stock  or other  equity  interests  of  ARDIS  pursuant  to the  ARDIS  Purchase
Agreement.

     "Adjusted  London  Interbank  Offered  Rate" has the  meaning  set forth in
Section 2.05(b).

     "Administrative Agent" means Toronto Dominion (Texas), Inc. in its capacity
as  administrative  agent for the Banks  hereunder,  and its  successors in such
capacity.

     "Administrative  Questionnaire"  means,  with  respect  to  each  Bank,  an
administrative  questionnaire in the form prepared by the  Administrative  Agent
and submitted to the  Administrative  Agent (with a copy to the  Borrower)  duly
completed by such Bank.



                                        1

<PAGE>



     "Affiliate"  means, as to any Person,  any other Person which,  directly or
indirectly, is in control of, is controlled by, or is under common control with,
such  Person.  A  Person  shall be  deemed  to  control  another  Person  if the
controlling  Person  possesses,  directly or indirectly,  the power to direct or
cause the direction of the management and policies of the other Person,  whether
through the ownership of voting  securities,  by contract or otherwise.  Without
limitation,  any director,  executive officer or beneficial owner of 25% or more
of the equity of a Person shall,  for the purposes of this Agreement,  be deemed
to control the other Person,  and each Shareholder  Guarantor shall be deemed to
be an Affiliate.

     "Agents" means the  Administrative  Agent and the Documentation  Agent, and
"Agent" means either of the foregoing.

     "AMRC Holdings" means AMRC Holdings, Inc., a Delaware corporation,  and its
successors.

     "Applicable  Lending  Office"  means,  with respect to any Bank, (i) in the
case of its Base Rate Loans, its Domestic Lending Office and (ii) in the case of
its Euro-Dollar Loans, its Euro-Dollar Lending Office.

     "ARDIS" means, collectively,  Motorola ARDIS Acquisition,  Inc., a Delaware
corporation,  Motorola  ARDIS,  Inc.,  a  Delaware  corporation,  ARDIS  Holding
Company, a New York general partnership, Radio Data Network Holding Corporation,
a Delaware corporation, and ARDIS Company, a New York general partnership.

     "ARDIS Purchase  Agreement" means the Stock Purchase  Agreement dated as of
December  31, 1997 among the  Borrower,  the Parent  Guarantor,  Motorola  Inc.,
Motorola ARDIS Acquisition, Inc. and Motorola ARDIS, Inc.

     "Asset Sale" means any sale, lease or other disposition (including any such
transaction  effected by way of merger or consolidation  and the Satellite Lease
Arrangements)  by the Parent  Guarantor or any of its Subsidiaries of any asset,
including  without  limitation any  sale-leaseback  transaction,  whether or not
involving a capital lease,  but excluding (i)  dispositions of inventory,  cash,
cash equivalents and other cash management  investments and obsolete,  unused or
unnecessary  equipment and undeveloped real estate, in each case in the ordinary
course of business and (ii) dispositions to the Parent Guarantor or a Subsidiary
of the Parent Guarantor.

     "Assignee" has the meaning set forth in Section 10.06(c).



                                        2

<PAGE>



     "Availability  Period" means the period from and including the Closing Date
to but not including the Termination Date.

     "Bank" means each bank listed on the signature pages hereof,  each Assignee
which  becomes  a Bank  pursuant  to  Section  10.06(c),  and  their  respective
successors.

     "Baron  Capital"  means Baron Capital  Partners,  L.P., a Delaware  limited
partnership.

     "Baron Capital  Guaranty"  means the Guaranty,  dated as of March 31, 1998,
made by Baron  Capital to the  Administrative  Agent for its own benefit and the
benefit of the Banks, as the same may be amended from time to time.

     "Baron Capital Letter of Credit" means the Letter of Credit dated March 31,
1998  issued by The Bank of New York for the  account of Baron  Capital  for the
benefit of the Administrative Agent on behalf of the Banks.

     "Base Rate" means, for any day, a rate per annum equal to the higher of (i)
the Prime Rate for such day and (ii) the sum of 5/8 of 1% plus the Federal Funds
Rate for such day.

     "Base Rate Loan"  means (i) a Loan which  bears  interest  at the Base Rate
pursuant  to the  applicable  Notice of  Borrowing  or Notice of  Interest  Rate
Election or the  provisions  of Article 8 or (ii) an overdue  amount which was a
Base Rate Loan immediately before it became overdue.

     "Borrower" means AMSC Acquisition  Company,  Inc., a Delaware  corporation,
and its successors.

     "Borrowing"  means a borrowing  hereunder  consisting  of Loans made to the
Borrower  on the same day  pursuant  to Article 2, all of which Loans are of the
same Type  (subject  to Article 8) and,  except in the case of Base Rate  Loans,
have the same initial Interest Period. A Borrowing is a "Base Rate Borrowing" if
such Loans are Base Rate Loans or a  "Euro-Dollar  Borrowing"  if such Loans are
Euro-Dollar Loans.

     "Capital  Lease  Obligations"  means all monetary  obligations  of a Person
under any leasing or similar  arrangement  which,  in  accordance  with GAAP, is
classified as a capital lease.

     "Cash Equivalents" means:



                                        3

<PAGE>



     (a) securities  issued or fully  guaranteed or insured by the United States
Government or any agency  thereof and backed by the full faith and credit of the
United States having  maturities of not more than twelve months from the date of
acquisition;

     (b) certificates of deposit,  time deposits,  Eurodollar time deposits,  or
bankers'  acceptances  having in each case a tenor of not more than six  months,
issued by any Bank, or by any U.S.  commercial bank having combined  capital and
surplus of not less than $500,000,000 whose short term securities are rated both
A-1 or higher by  Standard  & Poor's  Corporation  and P-1 or higher by  Moody's
Investors Services, Inc.;

     (c)  commercial  paper of an issuer rated either at least A-1 by Standard &
Poor's  Ratings  Group, a division of  McGraw-Hill,  Inc.  and/or P-1 by Moody's
Investors  Service Inc. and in either case having a tenor of not more than three
months;

     (d) repurchase  agreements  fully  collateralized  by securities  issued by
United States Government agencies; and

     (e) money market  mutual  funds  invested in the  instruments  permitted by
clauses (a), (b), (c) and (d) above.

     "CERCLA" has the meaning specified in the definition "Environmental Laws".

     "Change In  Control"  means (i) any person or group of persons  (within the
meaning of Section 13 or 14 of the Securities  Exchange Act of 1934, as amended)
(other than any Shareholder Guarantor, AT&T Wireless Services, Inc. or Motorola,
Inc.)  shall  have  beneficial  ownership  (within  the  meaning  of Rule  13d-3
promulgated by the Securities  and Exchange  Commission  under said Act) of more
than 25% of the outstanding  capital stock of the Parent Guarantor,  (ii) Hughes
shall have  beneficial  ownership  of less than 25% of the  outstanding  capital
stock of the Parent  Guarantor,  except  solely as a result of the  issuance  of
additional  capital stock by the Parent  Guarantor to Persons other than Hughes,
in which case a Change of Control under this clause (iii) shall not occur unless
Hughes  shall  have  beneficial  ownership  of less than 10% of the  outstanding
capital stock of the Parent Guarantor,  (iv) during any period of 24 consecutive
calendar  months,  individuals who were directors of the Parent Guarantor on the
first day of such period  shall cease to  constitute  a majority of the board of
directors of the Parent  Guarantor  (ignoring for this purpose  replacements  of
stockholder-designated  directors by successor directors  designated by the same



                                        4

<PAGE>



stockholder or group of stockholders),  or (iv) the Parent Guarantor shall cease
to own all of the outstanding capital stock of the Borrower.

     "Closing  Date" means the date on or after the Effective  Date on which the
Documentation  Agent shall have received the documents  specified in or pursuant
to Section 3.01(a).

     "Code"  means  the  Internal  Revenue  Code of  1986,  as  amended,  or any
successor statute.

     "Commitment"  means any  Tranche A  Commitment,  Tranche  B  Commitment  or
Tranche C Commitment,  and "Commitments"  means any or all of the foregoing,  as
the context may require.

     "Commitment Fee Percentage" means a rate per annum determined in accordance
with the Pricing Schedule.

     "Commitment  Reduction Date" means each March 31, June 30, September 30 and
December 31 from and including  June 30, 2002 to but  excluding the  Termination
Date.

     "Commitment Schedule" means the Commitment Schedule attached hereto.

     "Communications  Asset" means a terrestrial or satellite antenna,  licensed
site, base station,  communications ground segment, network operations center or
other telecommunications facility (other than a satellite).

     "Consolidated Capital Expenditures" means, for any period, the additions to
property, plant and equipment of the Borrower and its Consolidated  Subsidiaries
for such period, as determined in accordance with GAAP.

     "Consolidated  Current Assets" means at any date the  consolidated  current
assets of the Borrower and its Consolidated  Subsidiaries  determined as of such
date.

     "Consolidated  Current  Liabilities" means at any date (i) the consolidated
current liabilities of the Borrower and its Consolidated  Subsidiaries plus (ii)
the  Contingent  Obligations of the Borrower and its  Consolidated  Subsidiaries
with respect to the current  liabilities  of any Person (other than the Borrower
and its Consolidated Subsidiaries), all determined as of such date.



                                        5

<PAGE>



     "Consolidated  Net  Working  Investment"  means  at any  date  Consolidated
Current  Assets  (exclusive  of cash and cash  equivalents)  minus  Consolidated
Current Liabilities (exclusive of Indebtedness).

     "Consolidated Subsidiary" means at any date and with respect to any Person,
any Subsidiary or other entity the accounts of which would be consolidated  with
those of such Person in its consolidated financial statements if such statements
were prepared as of such date.

     "Contingent  Obligation"  means,  as applied to any  Person,  any direct or
indirect  liability  of that Person  with  respect to any  Indebtedness,  lease,
dividend,  letter of credit or other  obligation (the "primary  obligations") of
another  Person (the "primary  obligor"),  including,  without  limitation,  any
obligation  of  that  Person,  whether  or  not  contingent,  (a)  to  purchase,
repurchase  or  otherwise  acquire  such  primary  obligations  or any  property
constituting direct or indirect security therefor,  or (b) to advance or provide
funds (i) for the payment or discharge of any such primary  obligation,  or (ii)
to  maintain  working  capital  or equity  capital  of the  primary  obligor  or
otherwise to maintain the net worth or solvency or any balance sheet item, level
of income or  financial  condition  of the primary  obligor,  or (c) to purchase
property, securities or services primarily for the purpose of assuring the owner
of any such  primary  obligation  of the ability of the primary  obligor to make
payment of such primary obligation,  or (d) otherwise to assure or hold harmless
the holder of any such primary  obligation  against loss in respect thereof,  or
(e) to purchase or otherwise acquire,  or otherwise to assure a creditor against
loss in respect of any Indebtedness. For purposes of this definition, the amount
of any  Contingent  Obligation  shall be  deemed  to be an  amount  equal to the
maximum reasonably anticipated liability in respect thereof.

     "Contractual  Obligation"  means,  as to any Person,  any  provision of any
security  issued by such  Person  or of any  agreement,  undertaking,  contract,
indenture, mortgage, deed of trust or other instrument, document or agreement to
which such Person is a party or by which it or any of its property is bound.

     "Controlled Group" means the Parent Guarantor, the Borrower and all Persons
(whether  or not  incorporated)  under  common  control  or  treated as a single
employer  with the Parent  Guarantor,  the  Borrower or any of their  respective
Subsidiaries pursuant to Section 414(b), (c), (m) or (o) of the Code.

     "Default"  means  any  condition  or event  which  constitutes  an Event of
Default  or which  with the  giving of  notice  or lapse of time or both  would,
unless cured or waived, become an Event of Default.



                                        6

<PAGE>



     "Disclosure  Schedule" means the Disclosure  Schedule of even date herewith
attached hereto and hereby made part of this Agreement.

     "Documentation  Agent" means Morgan  Guaranty  Trust Company of New York in
its capacity as documentation agent for the Banks hereunder,  and its successors
in such capacity.

     "dollars" means United States dollars.

     "Domestic  Business  Day" means any day except a Saturday,  Sunday or other
day on which commercial banks in New York City are authorized by law to close.

     "Domestic Lending Office" means, as to each Bank, its office located at its
address set forth in its  Administrative  Questionnaire  (or  identified  in its
Administrative  Questionnaire  as its  Domestic  Lending  Office)  or such other
office as such Bank may hereafter  designate as its Domestic  Lending  Office by
notice to the Borrower and the Administrative Agent.

     "Effective  Date"  means  the date  this  Agreement  becomes  effective  in
accordance with Section 10.09.

     "Environmental   Claim"  means  all  claims,   however  asserted,   by  any
Governmental   Authority  or  other  Person  alleging  potential   liability  or
responsibility  for  violation  of any  Environmental  Law or for  injury to the
environment or threat to public health,  personal  injury  (including  sickness,
disease or death),  property  damage,  natural  resources  damage,  or otherwise
alleging  liability  or  responsibility  for damages  (punitive  or  otherwise),
cleanup,  removal,  remedial or response costs,  restitution,  civil or criminal
penalties,  injunctive relief, or other type of relief,  resulting from or based
upon (a) the  presence,  placement,  discharge,  emission or release  (including
intentional  and   unintentional,   negligent  and   non-negligent,   sudden  or
non-sudden,  accidental or non-accidental placements, spills, leaks, discharges,
emissions  or  releases)  of any  Hazardous  Material  at, in or from  property,
whether or not owned by the Borrower, or (b) any other circumstances forming the
basis of any violation, or alleged violation, of any Environmental Law.

     "Environmental Laws" means all applicable federal, state, local and foreign
laws,  statutes,  common law duties,  judicial  decisions,  rules,  regulations,
ordinances,  judgements  and codes,  together  with all  administrative  orders,
requests,  licenses,  authorizations  and permits of, and  agreements  with, any
Governmental Authorities,  in each case relating to the environment,  health and
safety  or  to   emissions,   discharges  or  releases,   or  the   manufacture,




                                        7

<PAGE>


distribution,  use,  treatment,  storage,  disposal,  transport or handling,  of
pollutants, contaminants, wastes or toxic or hazardous substances; including, as
they may be amended from time to time, the Comprehensive Environmental Response,
Compensation  and  Liability  Act of 1980  ("CERCLA"),  the Clean  Air Act,  the
Federal Water  Pollution  Control Act of 1972, the Solid Waste Disposal Act, the
Federal Resource Conservation and Recovery Act, the Toxic Substances Control Act
and the Emergency Planning and the Community Right-to-Know Act of 1986.

     "ERISA"  means the Employee  Retirement  Income  Security  Act of 1974,  as
amended, or any successor statute.

     "ERISA Event" means (a) a Reportable Event with respect to a Qualified Plan
or a Multiemployer  Plan; (b) a withdrawal by any member of the Controlled Group
from a Qualified  Plan  subject to Section  4063 of ERISA  during a plan year in
which it was a substantial employer (as defined in Section 4001(a)(2) of ERISA);
(c) a complete or partial  withdrawal by any member of the Controlled Group from
a  Multiemployer  Plan;  (d) the filing of a notice of intent to terminate,  the
treatment of a plan  amendment as a  termination  under Section 4041 or 4041A of
ERISA or the  commencement  of  proceedings by the PBGC to terminate a Qualified
Plan or  Multiemployer  Plan subject to Title IV of ERISA; (e) a failure to make
required  contributions to a Qualified Plan or Multiemployer  Plan; (f) an event
or condition  which might  reasonably  be expected to  constitute  grounds under
Section 4042 of ERISA for the termination of, or the appointment of a trustee to
administer,  any Qualified Plan or Multiemployer Plan; (g) the imposition of any
liability  under  Title  IV of  ERISA,  other  than  PBGC  premiums  due but not
delinquent under Section 4007 of ERISA, upon any member of the Controlled Group;
(h) an  application  for a funding  waiver or any extension of any  amortization
period  pursuant to Section 412 of the Code with respect to any Qualified  Plan;
or (i) any member of the Controlled Group engages in or otherwise becomes liable
for a non-exempt prohibited transaction.

     "Escrow  Letter" means the letter  agreement  dated March 31, 1998 from the
Borrower to the Banks and the Agents.

     "Euro-Dollar  Business  Day"  means  any  Domestic  Business  Day on  which
commercial  banks are open for  international  business  (including  dealings in
dollar deposits) in London.

     "Euro-Dollar Lending Office" means, as to each Bank, its office,  branch or
affiliate located at its address set forth in its  Administrative  Questionnaire
(or identified in its  Administrative  Questionnaire as its Euro-Dollar  Lending
Office)  or such  other  office,  branch  or  affiliate  of such  Bank as it may



                                        8

<PAGE>


hereafter  designate as its Euro-Dollar Lending Office by notice to the Borrower
and the Administrative Agent.

     "Euro-Dollar  Loan" means (i) a Loan which bears  interest at a Euro-Dollar
Rate pursuant to the  applicable  Notice of Borrowing or Notice of Interest Rate
Election or (ii) an overdue  amount  which was a  Euro-Dollar  Loan  immediately
before it became overdue.

     "Euro-Dollar  Margin" means a rate per annum  determined in accordance with
the Pricing Schedule.

     "Euro-Dollar Rate" means a rate of interest  determined pursuant to Section
2.05(b) on the basis of an Adjusted London Interbank Offered Rate.

     "Euro-Dollar  Reserve  Percentage"  has the  meaning  set forth in  Section
2.05(b).

     "Event of Default" has the meaning set forth in Section 6.01.

     "Excess Cash Flow" means, for any fiscal year of the Borrower,  (i) the net
income of the Borrower and its  Consolidated  Subsidiaries for such fiscal year,
determined on a consolidated basis for such fiscal year, plus (ii) to the extent
deducted in determining  such net income,  the aggregate  amount of depreciation
and  amortization  and other similar non-cash charges for such fiscal year, plus
(iii) to the extent  deducted  in  determining  such net income,  the  aggregate
amount of income tax expense (other than cash taxes paid by the Borrower and its
Consolidated Subsidiaries during such fiscal year) plus (minus) (iv) the amount,
if any, of any  decrease  (increase)  in  Consolidated  Net  Working  Investment
between the  beginning and the end of such year minus (v)  Consolidated  Capital
Expenditures  for such  fiscal  year and  minus  (vi) the  aggregate  amount  of
scheduled   principal   payments  of   Indebtedness  of  the  Borrower  and  its
Consolidated Subsidiaries paid during such fiscal year by the Borrower or any of
its Consolidated Subsidiaries, determined on a consolidated basis.

     "Existing Credit  Facilities" means the $75,000,000  Credit Agreement dated
as of June 28, 1996 among AMSC Subsidiary Corporation, the Parent Guarantor, the
Banks  listed   therein,   Morgan   Guaranty  Trust  Company  of  New  York,  as
Documentation  Agent,  and Toronto  Dominion  (Texas),  Inc., as  Administrative
Agent,   together  with  the  Loan  Documents  referred  to  therein,   and  the
$150,000,000  Credit  Agreement  dated as of June 28, 1996 among AMSC Subsidiary
Corporation,  the Parent  Guarantor,  the Banks listed therein,  Morgan Guaranty


                                        9

<PAGE>


Trust Company of New York, as Documentation Agent, and Toronto Dominion (Texas),
Inc., as  Administrative  Agent,  together with the Loan  Documents  referred to
therein.

     "FCC" means the Federal Communications Commission or any successor thereto.

     "FCC Licenses"  means the licenses  identified in the Disclosure  Schedule,
together with each other material FCC license  obtained by the Parent  Guarantor
or any Subsidiary of the Parent Guarantor.

     "Federal  Funds  Rate"  means,  for any day,  the rate per  annum  (rounded
upward,  if  necessary,  to the  nearest  1/100th  of 1%) equal to the  weighted
average of the rates on overnight Federal funds transactions with members of the
Federal  Reserve  System  arranged  by Federal  funds  brokers  on such day,  as
published by the Federal  Reserve Bank of New York on the Domestic  Business Day
next  succeeding  such  day,  provided  that (i) if such  day is not a  Domestic
Business  Day,  the  Federal  Funds Rate for such day shall be such rate on such
transactions on the next preceding  Domestic Business Day as so published on the
next succeeding  Domestic Business Day, and (ii) if no such rate is so published
on such next succeeding  Domestic  Business Day, the Federal Funds Rate for such
day shall be the average rate quoted to The Toronto-Dominion Bank on such day on
such transactions as determined by the Administrative Agent.

     "GAAP" means  generally  accepted  accounting  principles  set forth in the
opinions and pronouncements of the Accounting  Principles Board and the American
Institute of Certified Public  Accountants and statements and  pronouncements of
the Financial  Accounting Standards Board (or agencies with similar functions of
comparable stature and authority within the accounting  profession),  or in such
other  statements  by such other entity as may be in general use by  significant
segments  of  the  U.S.  accounting  profession,  which  are  applicable  to the
circumstances as of the date of determination.

     "Government  Approvals"  means  any  authorizations,  consents,  approvals,
licenses (including FCC licenses),  leases,  rulings,  permits,  tariffs, rates,
certifications, exemptions, filings or registrations by or with any Governmental
Authority required to be obtained or held by the Borrower.

     "Governmental Authority" means any nation or government, any state or other
political  subdivision  thereof,  any  central  bank  (or  similar  monetary  or
regulatory  authority) thereof,  any entity exercising  executive,  legislative,
judicial, regulatory or administrative functions of or pertaining to government,
and any  corporation  or other  entity  owned or  controlled,  through  stock or
capital ownership or otherwise, by any of the foregoing.



                                       10

<PAGE>



     "Group of Loans" means at any time a group of Loans  consisting  of (i) all
Loans  which are Base  Rate  Loans at such  time or (ii) all  Euro-Dollar  Loans
having the same Interest  Period at such time,  provided  that, if a Loan of any
particular  Bank is converted to or made as a Base Rate Loan pursuant to Article
8, such Loan shall be included in the same Group or Groups of Loans from time to
time as it would have been in if it had not been so converted or made.

     "Guaranty  Issuance  Agreement" means the Guaranty Issuance Agreement dated
as of March 31, 1998, among Hughes, SingTel, Baron Capital, the Borrower and the
Parent Guarantor.

     "Guaranty Issuance Agreement Event of Default" has the meaning set forth in
the Guaranty Issuance Agreement.

     "Hazardous Materials" means all those substances which are regulated by, or
which may form the basis of liability under, any  Environmental  Law,  including
all  substances   identified  under  any   Environmental  Law  as  a  pollutant,
contaminant,  waste, solid waste,  hazardous  material,  hazardous  substance or
toxic  substance,  including  petroleum or any  petroleum  derived  substance or
byproduct.

     "Hughes" means Hughes Electronics Corporation, a Delaware corporation.

     "Hughes Bridge Loan Agreement"  means the Bridge Loan Agreement dated as of
December 30, 1997 by and among AMSC Subsidiary Corporation, the Parent Guarantor
and Hughes Communications Satellite Services, Inc.

     "Hughes  Guaranty" means the Guaranty,  dated as of March 31, 1998, made by
Hughes to the  Administrative  Agent for its own  benefit and the benefit of the
Banks, as the same may be amended from time to time.

     "Indebtedness"   of  any  Person  means   without   duplication,   (a)  all
indebtedness  for borrowed  money;  (b) all  obligations  issued,  undertaken or
assumed as the deferred purchase price of capital assets;  (c) all reimbursement
obligations  with  respect  to  surety  bonds,   letters  of  credit,   bankers'
acceptances  and similar  instruments  (in each case,  whether or not  matured),
excluding  performance bonds,  letters of credit and similar undertakings in the
ordinary  course  of  business  of  the  Borrower,   to  the  extent  that  such
undertakings  do not secure an  obligation  for  borrowed  money or the deferred
purchase  price of a capital  asset;  (d) all  obligations  evidenced  by notes,
bonds,  debentures or similar  instruments,  including  obligations so evidenced
incurred in connection with the  acquisition of property,  assets or businesses,
excluding  performance bonds,  letters of credit and similar undertakings in the
ordinary  course  of  business  of  the  Borrower,   to  the  extent  that  such



                                       11

<PAGE>


undertakings  do not secure an  obligation  for  borrowed  money or the deferred
purchase price of a capital asset; (e) all indebtedness created or arising under
any  conditional  sale or  other  title  retention  agreement,  or  incurred  as
financing,  in either case with respect to property acquired by the Person (even
though the rights and remedies of the seller or bank under such agreement in the
event of default are limited to repossession or sale of such property);  (f) all
Capital  Lease  Obligations;  (g)  all  net  obligations  with  respect  to Rate
Contracts; (h) sale-leaseback  financings;  (i) all Contingent Obligations;  and
(j) all Indebtedness  referred to in paragraphs (a) through (i) above secured by
any Lien upon or in property  (including  accounts and contract rights) owned by
such  Person,  even though such Person has not assumed or become  liable for the
payment  of  such  Indebtedness.  For  purposes  of  this  definition,  (i)  any
Indebtedness  of the Borrower to the Parent  Guarantor  which is subordinated to
the  Obligations on terms and conditions  satisfactory  to the Agents,  (ii) any
Indebtedness  of the  Borrower  to a  Subsidiary  of  the  Borrower,  (iii)  any
Indebtedness  of a Subsidiary of the Borrower to or from the Borrower or another
Subsidiary of the Borrower and (iv) any Indebtedness of Sales Corporation to the
Parent  Guarantor  or the  Borrower  consisting  of loans of amounts  that would
otherwise  have been  spent by the  Borrower  in  connection  with its sales and
marketing activities shall be excluded.

     "Indemnitee" has the meaning set forth in Section 10.03(b).

     "Interest  Period" means, with respect to each Euro-Dollar Loan, the period
commencing  on the date of  borrowing  specified  in the  applicable  Notice  of
Borrowing or on the date  specified in the  applicable  Notice of Interest  Rate
Election and ending one, two,  three or six months  thereafter,  as the Borrower
may elect in the applicable notice; provided that:

     (a) any Interest  Period which would  otherwise end on a day which is not a
Euro-Dollar  Business Day shall be extended to the next  succeeding  Euro-Dollar
Business  Day unless such  Euro-Dollar  Business  Day falls in another  calendar
month,  in which  case such  Interest  Period  shall  end on the next  preceding
Euro-Dollar Business Day;

     (b) any Interest Period which begins on the last  Euro-Dollar  Business Day
of a calendar month (or on a day for which there is no numerically corresponding
day in the calendar month at the end of such Interest Period) shall,  subject to
clause (c) below, end on the last Euro-Dollar  Business Day of a calendar month;
and

     (c) any Interest  Period which would  otherwise  end after the  Termination
Date shall end on the Termination Date.


                                       12

<PAGE>



     "Investment" means any investment in any Person,  whether by means of share
purchase,  capital contribution,  loan, Contingent  Obligation,  time deposit or
otherwise (but not including any demand deposit).

     "Joint  Venture" means any  corporation,  association,  partnership,  joint
venture or other business entity of which more than 10% but of which 50% or less
of the voting stock or other equity interests is owned or controlled directly or
indirectly by the Parent Guarantor or any of its Subsidiaries.

     "Lien"  means  any  mortgage,   deed  of  trust,   pledge,   hypothecation,
assignment,  charge or deposit  arrangement,  encumbrance,  lien  (statutory  or
other) or  preference,  priority  or other  security  interest  or  preferential
arrangement of any kind or nature  whatsoever  (including,  without  limitation,
those created by,  arising under or evidenced by any  conditional  sale or other
title  retention  agreement,  the  interest  of a lessor  under a Capital  Lease
Obligation, any financing lease having substantially the same economic effect as
any of the foregoing,  or the filing of any financing statement naming the owner
of the  asset to  which  such  lien  relates  as  debtor,  under  the UCC or any
comparable  law) and any  contingent  or other  agreement  to provide any of the
foregoing.

     "Loan"  means any  Tranche A Loan,  Tranche B Loan or  Tranche C Loan,  and
"Loans" means any or all of the foregoing, as the context may require.

     "Loan  Documents"  means this  Agreement,  each  Subsidiary  Guaranty,  the
Shareholder  Guaranties,  the Baron Capital Letter of Credit, all Rate Contracts
between the Borrower and any of the Banks and all  agreements,  instruments  and
documents executed and delivered in connection  herewith and therewith,  each as
amended, supplemented, waived or otherwise modified from time to time.

     "London  Interbank  Offered  Rate" has the  meaning  set  forth in  Section
2.05(b).

     "Major Casualty Event" means any loss of or damage to property  through one
or more related events for which the Parent Guarantor or any of its Subsidiaries
receives  any  insurance  proceeds  under any casualty  insurance  policy or any
condemnation  of property (or any transfer or disposition of property in lieu of
condemnation) for which the Parent Guarantor or any of its Subsidiaries receives
a condemnation award or other compensation,  with respect to which the aggregate
amount of such proceeds, award or other compensation exceeds $1,000,000.


                                       13

<PAGE>



     "Major  Contractual  Obligations"  means  the  obligations  of  the  Parent
Guarantor or any Subsidiary  thereof under the ACTEL Lease Agreement and the TMI
Purchase Agreement.

     "Material Adverse Effect" means a material adverse change in, or a material
adverse effect upon, any of (a) the operations,  business, properties, condition
(financial or otherwise) of either the Parent  Guarantor  Group taken as a whole
or the  Borrower  and its  Subsidiaries  taken as a whole;  (b) the  ability  or
prospective ability of the Parent Guarantor or the Borrower to perform under any
Loan  Document  or  any  Major  Contractual  Obligation;  or (c)  the  legality,
validity, binding effect or enforceability of any Loan Document.

     "MSAT-1"  means  the  satellite  that is the  subject  of the TMI  Purchase
Agreement.

     "MSAT-2"  means  the  satellite  that is the  subject  of the  ACTEL  Lease
Agreement.

     "Multiemployer  Plan" means a  "multiemployer  plan" (within the meaning of
Section  4001(a)(3) of ERISA) to which any member of the Controlled Group makes,
is making, or is obligated to make  contributions or has made, or been obligated
to make, contributions.

     "Net Cash Proceeds"  means,  with respect to any Reduction Event, an amount
equal to the cash proceeds  (including  lease  payments)  received by the Parent
Guarantor or any of its  Subsidiaries  (excluding  the proceeds  received by any
member  of  the  Parent   Guarantor  Group  other  than  the  Borrower  and  its
Subsidiaries  to the extent the  Reduction  Percentage  (as  defined in the Term
Credit  Agreement)  thereof is applied to the prepayment of Loans (as defined in
the Term Credit  Agreement) from or in respect of such Reduction Event, less any
out-of-pocket  costs  and  expenses  (excluding   administrative   expenses  and
overhead) reasonably incurred by such Person in respect of such Reduction Event;
provided that Net Cash Proceeds shall exclude any insurance proceeds received by
the Parent  Guarantor  or any of its  Subsidiaries  in respect of the loss of or
damage  to  MSAT-2  and  required  to be paid by the  Parent  Guarantor  or such
Subsidiary to ACTEL or its permitted assigns;  provided,  further, that Net Cash
Proceeds  received by the Parent Guarantor or any of its Subsidiaries in respect
of any period  under the ACTEL  Lease  Agreement  shall be reduced by the amount
paid by the Parent Guarantor or such Subsidiary during such period under the TMI
Purchase  Agreement  and,  without  duplication,  the amount  paid by the Parent
Guarantor  or such  Subsidiary  during  such  period  for up to  $50,000,000  of
insurance  for MSAT-1  required  to be  obtained  hereunder  or  required  to be
obtained by the Shareholder Guarantors.


                                       14

<PAGE>



     "Notes" means promissory  notes of the Borrower,  substantially in the form
of Exhibit A hereto,  evidencing  the  obligation  of the  Borrower to repay the
Loans, and "Note" means any one of such promissory notes issued hereunder.

     "Notice of Borrowing" has the meaning set forth in Section 2.02(a).

     "Notice of  Interest  Rate  Election"  has the meaning set forth in Section
2.08(a).

     "Notice of Lien" means any "notice of lien" or similar document intended to
be filed or recorded with any court, registry, recorder's office, central filing
office or  Governmental  Authority  for the  purpose  of  evidencing,  creating,
perfecting or preserving the priority of a Lien securing  obligations owing to a
Governmental Authority.

     "Obligations"  means all Loans, and other  Indebtedness,  advances,  debts,
liabilities,  and obligations,  owing by the Borrower to any Bank, any Agent, or
any other Person required to be indemnified under any Loan Document, of any kind
or nature,  present or future, whether or not evidenced by any note, guaranty or
other instrument,  arising under this Agreement,  under any other Loan Document,
whether  or not for the  payment  of  money,  whether  arising  by  reason of an
extension of credit,  loan,  guaranty,  indemnification  or in any other manner,
whether direct or indirect (including those acquired by assignment), absolute or
contingent,  due or to become due, now existing or hereafter arising and however
acquired.

     "Offering Memorandum" means the Preliminary Offering Memorandum dated March
9, 1998  relating to units  consisting  of Senior Notes and warrants to purchase
common stock of the Parent Guarantor.

     "Parent" means, with respect to any Bank, any Person controlling such Bank.

     "Parent Guarantor" means American Mobile Satellite Corporation,  a Delaware
corporation, and its successors.

     "Parent  Guarantor  Group" means the Parent  Guarantor and its Consolidated
Subsidiaries.

     "Participant" has the meaning set forth in Section 10.06(b).

     "PBGC"  means  the  Pension  Benefit  Guaranty  Corporation  or any  entity
succeeding to any or all of its functions under ERISA.


                                       15

<PAGE>



     "Permitted Liens" has the meaning set forth in Section 5.15.

     "Person" means an individual, a corporation, a limited liability company, a
partnership,  an  association,  a trust or any  other  entity  or  organization,
including a government or political  subdivision or an agency or instrumentality
thereof.

     "Plan" means an employee benefit plan (as defined in Section 3(3) of ERISA)
which any member of the  Controlled  Group sponsors or maintains or to which any
member of the Controlled Group makes or is obligated to make  contributions  and
includes any Multiemployer Plan or Qualified Plan.

     "Pricing Schedule" means the Pricing Schedule attached hereto.

     "Prime  Rate"  means  the  rate  of  interest  publicly  announced  by  The
Toronto-Dominion Bank in New York City from time to time as its Prime Rate.

     "Principal  Subsidiary"  means  at any time any  Subsidiary  of the  Parent
Guarantor, except Subsidiaries (other than the Borrower) which at such time have
been designated by the Parent Guarantor (by notice to the Administrative  Agent,
which may be amended from time to time) as nonmaterial  and which, if aggregated
and  considered  as a single  subsidiary,  would  not meet the  definition  of a
"significant  subsidiary"  contained as of the date hereof in Regulation  S-X of
the Securities and Exchange Commission.

     "Qualified Plan" means a pension plan (as defined in Section 3(2) of ERISA)
intended  to be  tax-qualified  under  Section  401(a) of the Code and which any
member of the Controlled Group sponsors,  maintains,  or to which it makes or is
obligated to make contributions or has made contributions at any time during the
immediately  preceding  period  covering  at  least  five (5)  plan  years,  but
excluding any Multiemployer Plan.

     "Quarterly Date" means March 31, June 30, September 30 and December 31.

     "Rate  Contracts"  means interest rate and currency swap  agreements,  cap,
floor and collar agreements,  interest rate insurance, currency spot and forward
contracts and other  agreements or arrangements  designed to provide  protection
against fluctuations in interest or currency exchange rates;  provided that such
agreements or arrangements are documented under master netting agreements.

     "Reduction Event" means (i) any Asset Sale, (ii) the issuance of any equity
securities by the Parent Guarantor or any of its Subsidiaries (other than equity



                                       16

<PAGE>


securities (x) issued pursuant to any stock option, stock purchase or other plan
intended to benefit or compensate  the  officers,  directors or employees of the
Parent  Guarantor,  the Borrower or any  Principal  Subsidiary,  but only to the
extent  that the Net Cash  Proceeds  thereof  in any  fiscal  year of the Parent
Guarantor do not exceed the sum of (A) $2,000,000 plus (B) the aggregate  amount
by which such Net Cash Proceeds  were less than  $2,000,000 in each prior fiscal
year of the Parent  Guarantor  after the date  hereof,  (y) issued to the Parent
Guarantor or any of its  Subsidiaries  or (z) issued by AMRC  Holdings or any of
its  Subsidiaries)  or (iii)  the  occurrence  of a Major  Casualty  Event.  The
description of any  transaction as falling within the above  definition does not
affect  any  limitation  on  such  transaction  imposed  by  Article  5 of  this
Agreement.

     "Reduction  Percentage"  means (i) in respect of an Asset Sale  (other than
the Satellite  Lease  Arrangements)  or a Major Casualty  Event,  100%,  (ii) in
respect of the Satellite Lease  Arrangements,  100% for the first $25,000,000 of
Net Cash Proceeds with respect  thereto and 75% for any such additional Net Cash
Proceeds,  (iii) in respect of Excess Cash Flow,  100% or (iv) in respect of the
issuance  of  equity  securities  (other  than  (x) to a  member  of the  Parent
Guarantor Group or (y) to a Shareholder Guarantor as part of a private placement
to one or more Shareholder Guarantors) by the Parent Guarantor or any Subsidiary
thereof, 50%.

     "Reference  Banks" means the principal  London  offices of Morgan  Guaranty
Trust Company of New York, The Toronto-Dominion Bank and any other Bank which is
appointed a Reference Bank by the Agents after  consultation  with the Borrower,
and "Reference Bank" means any one of such Reference Banks.

     "Regulation U" means  Regulation U of the Board of Governors of the Federal
Reserve System, as in effect from time to time.

     "Reportable  Event"  means any of the events  set forth in Section  4043 of
ERISA or the  regulations  thereunder,  a  withdrawal  from a Plan  described in
Section 4063 of ERISA, or a cessation of operations described in Section 4062(e)
of ERISA.

     "Required  Banks"  means  at any time  Banks  having  more  than 50% of the
aggregate  amount of the  Commitments  or, if the  Commitments  shall  have been
terminated,  holding  Notes  evidencing  more than 50% of the  aggregate  unpaid
principal amount of the Loans.

     "Requirement  of  Law"  means,  as to any  Person,  any law  (statutory  or
common),  treaty,  rule or regulation or  determination of an arbitrator or of a
Governmental Authority, in each case applicable to or binding upon the Person or
any of its property or to which the Person or any of its property is subject; in



                                       17

<PAGE>


any case,  non-compliance  with which by either of the Parent  Guarantor  or the
Borrower or their  Subsidiaries  could reasonably be expected to have a Material
Adverse Effect.

     "Responsible  Officer"  means,  with  respect  to  any  Person,  the  Chief
Executive  Officer,  the President or a duly  authorized Vice President or, with
respect to financial matters,  the Chief Financial Officer or the Treasurer,  of
such Person.

     "Sales  Corporation" means American Mobile Satellite Sales  Corporation,  a
Delaware corporation.

     "Satellite Lease  Arrangements"  means the sale or lease of MSAT-2 pursuant
to the ACTEL Agreement or a replacement  agreement (an "MSAT-2 Lease Agreement")
provided that any such replacement agreement shall be on commercially reasonable
terms,  and  provided  that (A) the  consideration  received by the  Borrower in
respect of such sale or lease (x)  consists  solely of cash and (y)  constitutes
fair market value (as  determined  by the Board of Directors of the Borrower set
forth in a resolution  thereof  delivered  to the  Administrative  Agent,  which
determination shall be based upon an opinion or appraisal issued by an appraisal
or investment  banking firm of national  standing);  (B) the Borrower shall have
acquired  (through  purchase  or  lease)  capacity  on  MSAT-1  or a  reasonable
substitute  thereof either (x) pursuant to the TMI Purchase Agreement or (y) any
other  agreement  with a term not less than the maximum term of the MSAT-2 Lease
Agreement then in effect and otherwise on commercially  reasonable  terms if (in
the  case  of  this  clause  (y))  in the  opinion  of a  nationally  recognized
independent  expert  (a) the  capacity  acquired  pursuant  to such  replacement
agreement  is  sufficient  to permit the Borrower to conduct its  operations  as
conducted  and as  contemplated  to be conducted  through the term of the MSAT-2
Lease  Agreement  then in  effect  and (b) the total  consideration  paid by the
Borrower  for such  replacement  satellite  capacity is no greater than the fair
market value thereof.

     "Senior Notes" means the Borrower's 12 1/4% Senior Notes due 2008.

     "Shareholder Guarantor Security Agreement" means the Reimbursement Security
and Pledge Agreement dated as of March 31, 1998 between the Parent Guarantor and
Hughes.

     "Shareholder Guarantors" means Hughes, SingTel and Baron Capital.

     "Shareholder  Guaranties"  means the Hughes Guaranty,  the SingTel Guaranty
and the Baron Capital Guaranty.



                                       18

<PAGE>



     "SingTel" means Singapore  Telecommunications Ltd., a corporation organized
under the laws of Singapore.

     "SingTel Guaranty" means the Guaranty,  dated as of March 31, 1998, made by
SingTel to the  Administrative  Agent for its own benefit and the benefit of the
Banks, as the same may be amended from time to time.

     "Subsidiary"  means,  as to any Person,  any corporation or other entity of
which  securities or other ownership  interests  having ordinary voting power to
elect a majority of the board of directors or other persons  performing  similar
functions are at the time directly or indirectly owned by such Person.

     "Subsidiary   Guaranty"   means  each  Subsidiary   Guaranty   between  the
Administrative Agent and a Subsidiary of the Borrower, substantially in the form
of Exhibit E hereto.

     "Term Credit  Agreement"  means the Term Credit  Agreement  dated as of the
date  hereof  among the Parent  Guarantor,  the Agents and the other banks party
thereto,  as the  same  may be  amended,  supplemented,  restated  or  otherwise
modified from time to time.

     "Termination  Date"  means  March  31,  2003,  or,  if  such  day  is not a
Euro-Dollar  Business Day, the next succeeding  Euro-Dollar  Business Day unless
such Euro-Dollar Business Day falls in another calendar month, in which case the
Termination Date shall be the next preceding Euro-Dollar Business Day.

     "TMI Purchase Agreement" means the Satellite Purchase Agreement dated as of
December 4, 1997 between TMI Communications and Company, Limited Partnership and
the Parent Guarantor.

     "Tranche A  Commitment"  means (i) with  respect to each Bank listed on the
Commitment  Schedule,  the amount set forth  opposite its name under the heading
"Tranche A Commitments" in the Commitment  Schedule and (ii) with respect to any
Assignee,  the amount of the transferor Bank's Tranche A Commitment  assigned to
such  Assignee  pursuant  to Section  10.06,  in each case as such amount may be
reduced  from time to time  pursuant  to  Section  2.07 or 2.09 or  changed as a
result of an assignment pursuant to Section 10.06.

     "Tranche B  Commitment"  means (i) with  respect to each Bank listed on the
Commitment  Schedule,  the amount set forth  opposite its name under the heading
"Tranche B Commitments" in the Commitment  Schedule and (ii) with respect to any
Assignee,  the amount of the transferor Bank's Tranche B Commitment  assigned to



                                       19

<PAGE>


such  Assignee  pursuant  to Section  10.06,  in each case as such amount may be
reduced  from time to time  pursuant  to  Section  2.07 or 2.09 or  changed as a
result of an assignment pursuant to Section 10.06.

     "Tranche C  Commitment"  means (i) with  respect to each Bank listed on the
Commitment  Schedule,  the amount set forth  opposite its name under the heading
"Tranche C Commitments" in the Commitment  Schedule and (ii) with respect to any
Assignee,  the amount of the transferor Bank's Tranche C Commitment  assigned to
such  Assignee  pursuant  to Section  10.06,  in each case as such amount may be
reduced  from time to time  pursuant  to  Section  2.07 or 2.09 or  changed as a
result of an assignment pursuant to Section 10.06.

     "Tranche A Loan" means a loan made by a Bank  pursuant to Section 2.01 as a
Tranche A Loan.

     "Tranche B Loan" means a loan made by a Bank  pursuant to Section 2.01 as a
Tranche B Loan.

     "Tranche C Loan" means a loan made by a Bank  pursuant to Section 2.01 as a
Tranche C Loan.

     "Type", when used in reference to any Loan or Borrowing,  refers to whether
the rate of interest on such Loan, or on the Loans  compromising such Borrowing,
is determined by reference to the Euro-Dollar Rate or the Base Rate.

     "UCC" means the Uniform Commercial Code as in effect in any jurisdiction.

     "Unfunded  Pension  Liabilities"  means  the  excess  of a  Plan's  accrued
benefits,  as defined in Section 3(23) of ERISA,  over the current value of that
Plan's assets, as defined in Section 3(26) of ERISA.

     "United  States" means the United  States of America,  including the States
and the District of Columbia, but excluding its territories and possessions.

     "Vendor Financing  Indebtedness" means Indebtedness incurred by a member of
the Parent  Guarantor Group the proceeds of which are utilized solely to acquire
ground-based Communications Assets.

     "Withdrawal Liabilities" means, as of any determination date, the aggregate
amount of the  liabilities,  if any,  pursuant  to Section  4201 of ERISA if the
Controlled Group made a complete withdrawal from all Multiemployer Plans and any
increase in contributions pursuant to Section 4243 of ERISA.


                                       20

<PAGE>



     SECTION  1.02.  Accounting  Terms  and  Determinations.   Unless  otherwise
specified  herein,  all accounting  terms used herein shall be interpreted,  all
accounting  determinations hereunder shall be made, and all financial statements
required to be delivered  hereunder shall be prepared in accordance with GAAP as
in effect from time to time,  applied on a basis consistent  (except for changes
concurred in by the Parent  Guarantor's  and the Borrower's  independent  public
accountants)  with the most recent audited  consolidated  or combined  financial
statements  of each the  Parent  Guarantor,  the Parent  Guarantor  Group or the
Borrower and its Consolidated Subsidiaries, as the case may be, delivered to the
Banks;  provided  that,  if the Parent  Guarantor or the  Borrower  notifies the
Administrative  Agent that it wishes to amend the  definition  of  "Excess  Cash
Flow" in Section 1.01 or any  covenant in Article 5 to  eliminate  the effect of
any change in GAAP on the operation of such  covenant (or if the  Administrative
Agent  notifies the Parent  Guarantor and the Borrower  that the Required  Banks
wish to amend  Section  1.01 or  Article 5 for such  purpose),  then the  Parent
Guarantor's and the Borrower's compliance with such covenant shall be determined
on the basis of GAAP in effect  immediately  before the relevant  change in GAAP
became  effective,  until either such notice is  withdrawn  or such  covenant is
amended in a manner  satisfactory to the Parent Guarantor,  the Borrower and the
Required Banks.



                                    ARTICLE 2
                                   THE CREDITS

     SECTION 2.01.  Commitments to Lend.  During the Availability  Period,  each
Bank severally  agrees, on the terms and conditions set forth in this Agreement,
to lend to the Borrower from time to time amounts not to exceed in the aggregate
the amount of its Commitments.  Each Borrowing under this Section shall be in an
aggregate  principal  amount of $5,000,000 or any larger  multiple of $1,000,000
(except that any such  Borrowing  may be in the  aggregate  amount of the unused
Commitments),  shall be made from the several  Banks  ratably in  proportion  to
their respective  Commitments and shall be made by each Bank as Tranche A Loans,
Tranche B Loans and  Tranche C Loans  ratably  in  proportion  to its  Tranche A
Commitment,  Tranche B Commitment and Tranche C Commitment. Within the foregoing
limits,  the Borrower may borrow under this Section,  prepay Loans to the extent
permitted  by Section  2.10 and  reborrow  at any time  during the  Availability
Period under this Section.

     SECTION  2.02.  Method  of  Borrowing.  (a) The  Borrower  shall  give  the
Administrative  Agent irrevocable  telephonic notice,  confirmed  immediately in




                                       21

<PAGE>


writing  (a  "Notice of  Borrowing"),  not later than 10:30 A.M.  (New York City
time) on (x) the Domestic  Business Day before each Base Rate  Borrowing and (y)
the  third   Euro-Dollar   Business  Day  before  each  Euro-Dollar   Borrowing,
specifying:

          (i) the date of such Borrowing, which shall be a Domestic Business Day
          in the case of a Base Rate Borrowing or a Euro-Dollar  Business Day in
          the case of a Euro-Dollar Borrowing;

          (ii) the aggregate amount of such Borrowing;

          (iii) whether the Loans comprising such Borrowing are to bear interest
          initially at the Base Rate or a Euro-Dollar Rate; and

          (iv) in the  case of a  Euro-Dollar  Borrowing,  the  duration  of the
          Interest Period applicable  thereto,  subject to the provisions of the
          definition of Interest Period.

In no  event  shall  the  total  number  of  Groups  of  Loans  at any one  time
outstanding  exceed ten,  and each Group of Loans shall at all times  consist of
Tranche A Loans,  Tranche B Loans and  Tranche C Loans of the Banks  ratably  in
proportion to their respective Tranche A Commitments,  Tranche B Commitments and
Tranche C Commitments.

     (b) Upon receipt of a Notice of Borrowing,  the Administrative  Agent shall
promptly notify each Bank of the contents thereof,  of such Bank's ratable share
of such Borrowing and of the portion  thereof which shall be made as a Tranche A
Loan, a Tranche B Loan and a Tranche C Loan.

     (c) Not later  than  12:00  Noon  (New York City  time) on the date of each
Borrowing,  each Bank shall make available its ratable share of such  Borrowing,
in  Federal  or other  funds  immediately  available  in New York  City,  to the
Administrative  Agent at its  address  referred to in Section  5.03.  Unless the
Administrative  Agent  determines  that any  applicable  condition  specified in
Article 3 has not been satisfied,  the Administrative  Agent will make the funds
so received  from the Banks  available  to the  Borrower  at the  Administrative
Agent's aforesaid address.

     (d) Unless the Administrative  Agent shall have received notice from a Bank
prior to the date of any Borrowing that such Bank will not make available to the
Administrative  Agent such Bank's share of such  Borrowing,  the  Administrative
Agent  may  assume  that  such  Bank  has  made  such  share  available  to  the
Administrative Agent on the date of such Borrowing in accordance with subsection




                                       22

<PAGE>


(c) of this  Section and the  Administrative  Agent may,  in reliance  upon such
assumption,  make available to the Borrower on such date a corresponding amount.
If and to the extent that such Bank shall not have so made such share  available
to the Administrative Agent, such Bank and the Borrower severally agree to repay
to the  Administrative  Agent  forthwith  on demand  such  corresponding  amount
together with interest  thereon,  for each day from the date such amount is made
available  to  the  Borrower  until  the  date  such  amount  is  repaid  to the
Administrative Agent, at (i) in the case of the Borrower, a rate per annum equal
to the higher of the Federal Funds Rate and the interest rate applicable thereto
pursuant to Section  2.05 and (ii) in the case of such Bank,  the Federal  Funds
Rate. If such Bank shall repay to the  Administrative  Agent such  corresponding
amount, such amount so repaid shall constitute such Bank's Loan included in such
Borrowing for purposes of this Agreement.

     SECTION 2.03. Notes. (a) The Tranche A Loans, Tranche B Loans and Tranche C
Loans of each Bank shall each be evidenced by a single Note payable to the order
of such Bank for the account of its Applicable Lending Office in an amount equal
to the aggregate unpaid principal amount of such Bank's Tranche A Loans, Tranche
B Loans  and  Tranche  C  Loans,  as the  case may be.  Each  reference  in this
Agreement  to the  "Notes" of a Bank shall be deemed to refer to and include any
or all of the Notes of such Bank  described in this Section,  as the context may
require.

     (b) Each Bank may, by notice to the Borrower and the Administrative  Agent,
request  that its  Tranche A Loans,  Tranche  B Loans  and  Tranche C Loans of a
particular  Type be  evidenced  by a  separate  Note in an  amount  equal to the
aggregate  unpaid  principal  amount of such  Loans.  Each such Note shall be in
substantially  the form of Exhibit A hereto with  appropriate  modifications  to
reflect the fact that it evidences solely Loans of the relevant Type.

     (c) Upon  receipt of each Bank's  Notes  pursuant to Section  3.01(a),  the
Documentation  Agent  shall  forward  such Notes to such  Bank.  Each Bank shall
record the date, amount and Type of each Loan made by it and the date and amount
of each payment of principal  made by the Borrower  with respect  thereto on the
appropriate  Note,  and may,  if such  Bank so  elects  in  connection  with any
transfer or enforcement of any of its Notes,  endorse on the schedule  forming a
part thereof  appropriate  notations to evidence the foregoing  information with
respect to each Loan then outstanding  thereunder;  provided that the failure of
any Bank to make any such  recordation  or  endorsement  shall  not  affect  the
obligations  of the Borrower  hereunder or under the Notes.  Each Bank is hereby
irrevocably  authorized by the Borrower so to endorse its Notes and to attach to
and make a part of its Notes a  continuation  of any such  schedule  as and when
required.


                                       23

<PAGE>



     SECTION 2.04.  Maturity of Loans. Any Loans  outstanding on the Termination
Date (together with accrued  interest  thereon) shall be due and payable on such
date.

     SECTION 2.05.  Interest Rates.  (a) Each Base Rate Loan shall bear interest
on the outstanding  principal  amount  thereof,  for each day from the date such
Loan is made until it becomes  due,  at a rate per annum  equal to the Base Rate
for such day.  Such  interest  shall be  payable  quarterly  in  arrears on each
Quarterly  Date and, with respect to the principal  amount of any Base Rate Loan
converted to a Euro-Dollar  Loan, on each date a Base Rate Loan is so converted.
Any overdue  principal of or interest on any Base Rate Loan shall bear interest,
payable on demand,  for each day until paid at a rate per annum equal to the sum
of 2% plus the rate otherwise applicable to Base Rate Loans for such day.

     (b) Each Euro-Dollar Loan shall bear interest on the outstanding  principal
amount thereof,  for each day during each Interest Period applicable thereto, at
a rate per annum  equal to the sum of the  Euro-Dollar  Margin for such day plus
the Adjusted London  Interbank  Offered Rate applicable to such Interest Period.
Such interest shall be payable for each Interest  Period on the last day thereof
and, if such Interest Period is longer than three months,  at intervals of three
months after the first day thereof.

     The "Adjusted  London  Interbank  Offered Rate"  applicable to any Interest
Period means a rate per annum equal to the quotient obtained (rounded upward, if
necessary,  to the next higher  1/10,000 of 1%) by dividing  (i) the  applicable
London  Interbank  Offered  Rate by (ii)  1.00  minus  the  Euro-Dollar  Reserve
Percentage.

     The "London Interbank Offered Rate" applicable to any Interest Period means
the average (rounded upward, if necessary, to the next higher 1/16 of 1%) of the
respective  rates per annum at which  deposits in dollars are offered to each of
the Reference Banks in the London interbank  market at approximately  11:00 A.M.
(London  time)  two  Euro-Dollar  Business  Days  before  the  first day of such
Interest Period in an amount  approximately equal to the principal amount of the
Euro-Dollar  Loan of such  Reference  Bank to which such  Interest  Period is to
apply and for a period of time comparable to such Interest Period.

     "Euro-Dollar   Reserve  Percentage"  means  for  any  day  that  percentage
(expressed  as a decimal)  which is in effect on such day, as  prescribed by the
Board  of  Governors  of the  Federal  Reserve  System  (or any  successor)  for
determining  the maximum  reserve  requirement  for a member bank of the Federal
Reserve System in New York City with deposits  exceeding five billion dollars in



                                       24

<PAGE>


respect of  "Eurocurrency  liabilities"  (or in respect of any other category of
liabilities  which includes  deposits by reference to which the interest rate on
Euro-Dollar Loans is determined or any category of extensions of credit or other
assets which includes loans by a non-United  States office of any Bank to United
States residents).  The Adjusted London Interbank Offered Rate shall be adjusted
automatically  on and as of the effective date of any change in the  Euro-Dollar
Reserve Percentage.

     (c) Any overdue principal of or interest on any Euro-Dollar Loan shall bear
interest,  payable on demand,  for each day until paid at a rate per annum equal
to the higher of (i) the sum of 2% plus the Euro-Dollar Margin for such day plus
the quotient obtained (rounded upward, if necessary, to the next higher 1/10,000
of 1%) by dividing (x) the average  (rounded upward,  if necessary,  to the next
higher  1/16 of 1%) of the  respective  rates per annum at which one day (or, if
such amount due remains unpaid more than three  Euro-Dollar  Business Days, then
for such other  period of time not longer than six months as the  Administrative
Agent may select) deposits in dollars in an amount  approximately  equal to such
overdue payment due to each of the Reference Banks are offered to such Reference
Bank in the London  interbank  market for the  applicable  period  determined as
provided above by (y) 1.00 minus the Euro-Dollar  Reserve Percentage (or, if the
circumstances  described in clause (a) or (b) of Section 8.01 shall exist,  at a
rate per  annum  equal to the sum of 2% plus the rate  applicable  to Base  Rate
Loans for such day) and (ii) the sum of 2% plus the Euro-Dollar  Margin for such
day plus the Adjusted London  Interbank  Offered Rate applicable to such Loan at
the date such payment was due.

     (d) The Administrative  Agent shall determine each interest rate applicable
to the Loans hereunder. The Administrative Agent shall give prompt notice to the
Borrower and the participating Banks of each rate of interest so determined, and
its determination thereof shall be conclusive in the absence of manifest error.

     (e)  Each  Reference  Bank  agrees  to use  its  best  efforts  to  furnish
quotations to the Administrative  Agent as contemplated by this Section.  If any
Reference Bank does not furnish a timely  quotation,  the  Administrative  Agent
shall  determine  the relevant  interest  rate on the basis of the  quotation or
quotations  furnished by the  remaining  Reference  Bank or Banks or, if none of
such  quotations is available on a timely basis,  the provisions of Section 8.01
shall apply.

     SECTION 2.06. Commitment Fees. During the Availability Period, the Borrower
shall pay to the  Administrative  Agent for the account of the Banks  ratably in
proportion to their  Commitments a commitment  fee equal to the  Commitment  Fee




                                       25

<PAGE>


Percentage  per annum of the daily amount by which the  aggregate  amount of the
Commitments  exceeds the aggregate  outstanding  principal  amount of the Loans.
Such  commitment  fee shall accrue from and including the Effective  Date to but
excluding the date of termination  of the  Commitments  in their  entirety,  and
shall be payable  quarterly in arrears on each Quarterly Date and on the date of
termination of the  Commitments in their  entirety.  Any overdue fees shall bear
interest,  payable on demand,  for each day until paid at a rate per annum equal
to the sum of 2% plus the rate otherwise  applicable to Base Rate Loans for such
day.

     SECTION 2.07. Optional Termination or Reduction of Commitments.  (a) During
the Availability Period, the Borrower may, upon at least three Domestic Business
Days' notice to the  Administrative  Agent, (i) terminate the Commitments at any
time, if no Loans are outstanding at such time, or (ii) ratably reduce from time
to time by an aggregate amount of $5,000,000 or a larger multiple of $1,000,000,
the aggregate  amount of the Commitments in excess of the aggregate  outstanding
principal  amount of the Loans.  Each reduction of Commitments  pursuant to this
Section 2.07 shall be applied  ratably to the respective  Tranche A Commitments,
Tranche B Commitments and Tranche C Commitments of the Banks.

     (b) Upon receipt of a notice of  reduction  pursuant to this  Section,  the
Administrative Agent shall promptly notify each Bank of the contents thereof, of
such  Bank's  ratable  share  of  such  reduction  and  of the  portion  thereof
applicable to the Tranche A  Commitments,  Tranche B  Commitments  and Tranche C
Commitments, and such notice shall not thereafter be revocable by the Borrower.

     SECTION 2.08.  Method of Electing Interest Rates. (a) The Loans included in
each  Borrowing  shall bear interest  initially at the type of rate specified by
the Borrower in the applicable Notice of Borrowing. Thereafter, the Borrower may
from time to time elect to change or continue the type of interest rate borne by
each Group of Loans  (subject in each case to the  provisions  of Article 8), as
follows:

               (i) if such Loans are Base Rate Loans,  the Borrower may elect to
               convert  such Loans to  Euro-Dollar  Loans as of any  Euro-Dollar
               Business Day and

               (ii) if such Loans are Euro-Dollar  Loans, the Borrower may elect
               to convert  such  Loans to Base Rate  Loans or elect to  continue
               such  Loans  as  Euro-Dollar  Loans  for an  additional  Interest
               Period,  subject  to  Section  2.12  in  the  case  of  any  such
               conversion  or  continuation  effective on any day other than the
               last day of the then current  Interest Period  applicable to such
               Loans.


                                       26

<PAGE>




Each  such  election  shall be made by  giving  irrevocable  telephonic  notice,
confirmed  immediately in writing (a "Notice of Interest Rate  Election") to the
Administrative Agent not later than 10:30 A.M. (New York City time) on the third
Euro-Dollar Business Day before the conversion or continuation  selected in such
notice is to be  effective.  A Notice of Interest  Rate  Election  may, if it so
specifies,  apply to only a portion  of the  aggregate  principal  amount of the
relevant  Group of Loans;  provided  that (i) such portion is allocated  ratably
among the Loans  comprising such Group and (ii) the portion to which such Notice
applies,  and the  remaining  portion  to  which  it does  not  apply,  are each
$5,000,000 or any larger multiple of $1,000,000.

     (b) Each Notice of Interest Rate Election shall specify:

               (i) the  Group of Loans  (or,  subject  to the last  sentence  of
               Section 2.02(a), portion thereof) to which such notice applies;

               (ii) the date on which the conversion or continuation selected in
               such  notice is to be  effective,  which  shall  comply  with the
               applicable clause of subsection (a) above;

               (iii) if the Loans comprising such Group are to be converted, the
               new Type of Loans and,  if the Loans  being  converted  are to be
               Euro-Dollar  Loans, the duration of the next succeeding  Interest
               Period applicable thereto; and

               (iv) if such Loans are to be continued as  Euro-Dollar  Loans for
               an additional  Interest  Period,  the duration of such additional
               Interest Period.

Each  Interest  Period  specified in a Notice of Interest  Rate  Election  shall
comply with the  provisions of the  definition  of Interest  Period set forth in
Section 1.01.

     (c) If,  upon the  expiration  of any  Interest  Period  applicable  to any
Eurodollar  Loan,  the Borrower has not given a timely  Notice of Interest  Rate
Election with respect to such Loan, the Administrative  Agent shall be deemed to
have  received a Notice of Interest Rate Election from the Borrower with respect
to such Loan requesting that such Loan be converted into a Base Rate Loan on the
last day of the Interest Period applicable to such Loan.

     (d) Upon receipt of a Notice of Interest  Rate  Election  from the Borrower
pursuant  to  subsection  (a) above or a deemed  receipt of a Notice of Interest



                                       27

<PAGE>


Rate Election pursuant to subsection (c) above, the  Administrative  Agent shall
promptly  notify each Bank of the  contents  thereof  and such notice  shall not
thereafter be revocable by the Borrower.

     (e) An election by the  Borrower to change or continue the rate of interest
applicable to any Group of Loans pursuant to this Section shall not constitute a
"Borrowing" subject to the provisions of Section 3.02.

     SECTION 2.09. Mandatory  Termination and Reduction of Commitments.  (a) The
Commitments shall terminate on the last day of the Availability Period.

     (b) On each Commitment  Reduction Date, the Commitments shall be reduced by
$10,000,000;  provided that if, during the 90-day period ending on and including
such Commitment Reduction Date, the Commitments shall have been reduced pursuant
to clause (c) below,  the  Commitments  shall be reduced only by the amount,  if
any, by which  $10,000,000  is greater than the amount by which the  Commitments
were reduced during such 90-day period pursuant to clause (c) below.

     (c) In addition:

               (i)  in  the  event  that  the  Parent  Guarantor  or  any of its
               Subsidiaries  shall at any time,  or from  time to time,  receive
               after the date  hereof  any Net Cash  Proceeds  of any  Reduction
               Event, the Commitments shall be reduced by an amount equal to the
               Reduction  Percentage  of such Net Cash  Proceeds  on the date of
               receipt of such Net Cash Proceeds; and

               (ii) on each date on which the Borrower is required to notify the
               Administrative  Agent of the Excess Cash Flow for any fiscal year
               pursuant to Section 5.02(b),  the Commitments shall be reduced by
               an amount equal to the  Reduction  Percentage of Excess Cash Flow
               for such fiscal year.

     (d) Each reduction of Commitments pursuant to this Section shall be applied
ratably to the  respective  Tranche A  Commitments,  Tranche B  Commitments  and
Tranche  C  Commitments  of  the  Banks.  The  amount  of any  reduction  of the
Commitments  pursuant to Section 2.07 or subsection (c) of this Section shall be
applied  to  reduce  the  amount  of  subsequent  scheduled  reductions  of  the
Commitments  pursuant  to  subsections  (a) and (b)  above in  inverse  order of
maturity;  provided that if the Commitments  are reduced  pursuant to subsection
(c) above  less than 90 days  prior to a  Commitment  Reduction  Date,  then the
portion,  if any, of such reduction not greater than (i)  $10,000,000  less (ii)
the aggregate amount of similar  reductions made less than 90 days prior to such
Commitment Reduction Date shall be applied in direct order of maturity.


                                       28

<PAGE>



     (e) On the date of any reduction of the Commitments  pursuant to subsection
(b) or (c) above,  the Borrower shall repay such principal amount of each Bank's
outstanding Tranche A Loans, Tranche B Loans and Tranche C Loans, if any, as may
be necessary so that after such  repayment the aggregate  outstanding  principal
amount of such Bank's Tranche A Loans,  Tranche B Loans and Tranche C Loans does
not exceed the amount of such Bank's Tranche A Commitments, Tranche B Commitment
and  Tranche  C  Commitment  as  so  reduced.   The  Borrower   shall  give  the
Administrative  Agent at least five  Euro-Dollar  Business  Days' notice of each
prepayment of Euro-Dollar Loans required pursuant to this subsection.

     SECTION  2.10.  Optional  Prepayments.  (a)  Subject  in  the  case  of any
Euro-Dollar  Borrowing  to Section  2.12,  the Borrower  may,  upon at least one
Domestic Business Day's notice to the Administrative  Agent, prepay any Group of
Base Rate Loans, or upon at least three Euro-Dollar Business Days' notice to the
Administrative  Agent,  prepay any Group of Euro-Dollar  Loans,  in each case in
whole  at any  time,  or from  time to  time  in  part  in  amounts  aggregating
$5,000,000 or any larger multiple of $1,000,000,  by paying the principal amount
to be prepaid  together with accrued interest thereon to the date of prepayment.
Each such optional  prepayment  shall be applied to prepay ratably the Tranche A
Loans, Tranche B Loans and Tranche C Loans of the several Banks included in such
Group.

     (b) Upon receipt of a notice of prepayment  pursuant to this  Section,  the
Administrative Agent shall promptly notify each Bank of the contents thereof and
of such  Bank's  ratable  share of such  prepayment  and such  notice  shall not
thereafter be revocable by the Borrower.

     SECTION 2.11.  General  Provisions as to Payments.  (a) The Borrower  shall
make each  payment  of  principal  of,  and  interest  on, the Loans and of fees
hereunder,  not later than 12:00 Noon (New York City time) on the date when due,
in  Federal  or other  funds  immediately  available  in New York  City,  to the
Administrative   Agent  at  its  address   referred  to  in  Section  5.03.  The
Administrative  Agent will promptly distribute to each Bank its ratable share of
each such payment  received by the  Administrative  Agent for the account of the
Banks, to be applied ratably to the Tranche A Loans, the Tranche B Loans and the
Tranche C Loans of the Banks.  Whenever any payment of principal of, or interest
on, the Base Rate Loans or of fees shall be due on a day which is not a Domestic
Business  Day,  the date for  payment  thereof  shall  be  extended  to the next
succeeding  Domestic  Business  Day.  Whenever any payment of  principal  of, or
interest  on,  the  Euro-Dollar  Loans  shall  be  due on a day  which  is not a
Euro-Dollar  Business Day, the date for payment thereof shall be extended to the




                                       29

<PAGE>


next succeeding  Euro-Dollar  Business Day unless such Euro-Dollar  Business Day
falls in another  calendar  month,  in which case the date for  payment  thereof
shall  be the  next  preceding  Euro-Dollar  Business  Day.  If the date for any
payment of  principal is extended by  operation  of law or  otherwise,  interest
thereon shall be payable for such extended time.

     (b) Unless the  Administrative  Agent shall have  received  notice from the
Borrower  prior to the date on which any  payment is due to the Banks  hereunder
that the Borrower will not make such payment in full, the  Administrative  Agent
may assume that the Borrower has made such payment in full to the Administrative
Agent on such date and the  Administrative  Agent  may,  in  reliance  upon such
assumption,  cause to be  distributed  to each  Bank on such due date an  amount
equal to the amount then due such Bank.  If and to the extent that the  Borrower
shall not have so made such payment, each Bank shall repay to the Administrative
Agent  forthwith on demand such amount  distributed  to such Bank  together with
interest thereon,  for each day from the date such amount is distributed to such
Bank until the date such Bank repays such amount to the Administrative Agent, at
the Federal Funds Rate.

     SECTION  2.12.  Funding  Losses.  If the  Borrower  makes  any  payment  of
principal  with  respect  to any  Euro-Dollar  Loan or any  Euro-Dollar  Loan is
converted (pursuant to Article 2, 6 or 8 or otherwise) on any day other than the
last  day of an  Interest  Period  applicable  thereto,  or the  last  day of an
applicable period fixed pursuant to Section 2.05(c), or if the Borrower fails to
borrow or prepay any  Euro-Dollar  Loans after notice has been given to any Bank
in accordance with Section  2.02(a),  2.09 or 2.10, the Borrower shall reimburse
each Bank within 15 days after demand for any resulting loss or expense incurred
by it (or by an  existing  or  prospective  Participant  in the  related  Loan),
including  (without  limitation) any loss incurred in obtaining,  liquidating or
employing  deposits from third  parties,  but  excluding  loss of margin for the
period  after any such  payment  or  conversion  or failure to borrow or prepay,
provided that such Bank shall have delivered to the Borrower a certificate as to
the amount of such loss or expense, which certificate shall be conclusive in the
absence of manifest error.

     SECTION 2.13. Computation of Interest and Fees. Interest based on the Prime
Rate and commitment  fees hereunder  shall be computed on the basis of a year of
365 days (or 366 days in a leap  year)  and paid for the  actual  number of days
elapsed (including the first day but excluding the last day). All other interest
shall be  computed  on the  basis of a year of 360 days and paid for the  actual
number of days elapsed (including the first day but excluding the last day).




                                       30

<PAGE>



                                    ARTICLE 3
                                   CONDITIONS

     SECTION 3.01. Closing.  The closing hereunder shall occur upon satisfaction
of the following conditions:

     (a) the  Documentation  Agent shall have received all of the following,  in
form and substance  satisfactory  to the  Documentation  Agent and in sufficient
copies for each Bank:

               (i) duly executed  Notes for the account of each Bank dated on or
               before the Closing Date  complying with the provisions of Section
               2.03;

               (ii) the articles or certificate of  incorporation of each of the
               Borrower, the Parent Guarantor,  the Borrower's  Subsidiaries and
               the  Shareholder  Guarantors  (other  than Baron  Capital)  as in
               effect on the Closing  Date,  certified by the Secretary of State
               or equivalent  official of the  jurisdiction of  incorporation of
               such Person as of a recent date and by the Secretary or Assistant
               Secretary of such Person as of the Closing  Date,  and the bylaws
               of such Person as in effect on the Closing Date, certified by the
               Secretary or Assistant Secretary of such Person as of the Closing
               Date;

               (iii) a good  standing  certificate  for each of the Borrower and
               the Parent  Guarantor from the Secretary of State of its state of
               incorporation  and each state where the  Borrower is qualified to
               do  business  as a  foreign  corporation  as  of a  recent  date,
               together  with a  bring-down  certificate  by telex or  telecopy,
               dated the Closing Date;

               (iv) copies of the  resolutions  of the board of directors of (x)
               the Borrower  approving and authorizing  the execution,  delivery
               and  performance  by the Borrower of this Agreement and the other
               Loan  Documents  to  be  delivered  by  it  and  authorizing  the
               borrowing  of the Loans,  certified as of the Closing Date by the
               Secretary or an Assistant Secretary of the Borrower, and (y) each
               of the Parent  Guarantor,  the  Borrower's  Subsidiaries  and the
               Shareholder  Guarantors (other than Baron Capital)  approving and
               authorizing  the  execution,  delivery  and  performance  by such
               Person of all Loan Documents to be delivered by it,  certified as
               of the Closing Date by the Secretary or an Assistant Secretary of
               such Person;

               (v) a certificate  of the Secretary or an Assistant  Secretary of
               each  of  the  Borrower,  the  Parent  Guarantor,   each  of  the




                                               31

<PAGE>


               Borrower's  Subsidiaries  and each  Shareholder  Guarantor (other
               than Baron Capital)  certifying the names and true  signatures of
               its  officers  authorized  to execute,  deliver and  perform,  as
               applicable, all Loan Documents to be delivered by it hereunder;

               (vi) a certificate signed by a Responsible Officer of each of the
               Borrower and the Parent Guarantor,  dated as of the Closing Date,
               stating that each of the conditions set forth in Sections 3.01(b)
               through (e) is satisfied as of such date;

               (vii) a Subsidiary  Guaranty  executed by each  Subsidiary of the
               Borrower;

               (viii) written advice relating to such Lien and judgment searches
               as either Agent shall have requested of the Parent  Guarantor and
               the Borrower,  and such termination statements or other documents
               as may be  necessary  to  release  any Lien in favor of any third
               party not otherwise permitted by Section 5.15;

               (ix) an opinion of (w) Randy S.  Segal,  counsel to the  Borrower
               and the Parent Guarantor,  substantially in the form of Exhibit B
               hereto, (x) counsel reasonably satisfactory to the Agents to each
               Shareholder Guarantor,  in form and substance satisfactory to the
               Documentation  Agent,  and (y)  Davis  Polk &  Wardwell,  special
               counsel  to the  Agents,  substantially  in the form of Exhibit C
               hereto;

               (x) a copy of the financial  statements  of the Parent  Guarantor
               referred  to  in  Section   4.10(a)  and  (b),   certified  by  a
               Responsible Officer of the Parent Guarantor;

               (xi) a Shareholder  Guaranty  duly  executed by each  Shareholder
               Guarantor,  the Baron  Capital  Letter of Credit  and the  Escrow
               Letter; and

               (xii)  all  documents  the  Documentation  Agent  may  reasonably
               request  relating to the  existence of the  Borrower,  any of the
               Borrower's Subsidiaries,  the Parent Guarantor or any Shareholder
               Guarantor,  the corporate  authority for and the validity of this
               Agreement, the Notes or the Shareholder Guaranties, and any other
               matters relevant hereto,  all in form and substance  satisfactory
               to the Documentation Agent;

     (b) all costs,  accrued and unpaid fees and  expenses  (including,  without
limitation,  participation  fees and legal fees and expenses) to the extent then
due and payable on the Closing  Date by the Borrower  hereunder  shall have been
paid;


                                       32

<PAGE>




     (c) the Borrower and the Parent Guarantor shall have received proceeds (net
of fees and interest  reserves) of not less than  $140,000,000 from the issuance
of the Senior Notes, all conditions to the Acquisition (including receipt of any
approvals of the FCC) shall have been satisfied and the  Acquisition  shall have
been consummated;

     (d) the Hughes Bridge Loan  Agreement  shall have been  terminated  and all
amounts payable thereunder shall have paid in full; and

     (e) the  Existing  Credit  Facilities  shall have been  terminated  and all
amounts payable thereunder shall have been paid in full.

The Documentation  Agent shall promptly notify the Borrower and the Banks of the
Closing  Date,  and such notice shall be  conclusive  and binding on all parties
hereto.

     SECTION 3.02. Borrowings.  The obligation of any Bank to make a Loan on the
occasion  of any  Borrowing  is subject  to the  satisfaction  of the  following
conditions:

     (a) the fact that the Closing Date shall have occurred on or prior to March
31, 1998;

     (b)  receipt  by the  Administrative  Agent of a  Notice  of  Borrowing  as
required by Section 2.02(a);

     (c)  the  fact  that,  immediately  after  any  Borrowing,   the  aggregate
outstanding  principal  amount of the Loans will not exceed the aggregate amount
of the Commitments;

     (d) the fact that, immediately before and after such Borrowing,  no Default
shall have occurred and be continuing; and

     (e) the fact that the  representations  and  warranties of the Borrower and
the Parent Guarantor  contained in the Loan Documents shall be true on and as of
the date of such Borrowing.

Each Borrowing  hereunder shall be deemed to be a representation and warranty by
the  Borrower and the Parent  Guarantor on the date of such  Borrowing as to the
facts specified in clauses (b) through (e) of this Section.



                                       33

<PAGE>



                                    ARTICLE 4
                         REPRESENTATIONS AND WARRANTIES

     Each of the Borrower and the Parent  Guarantor  represents and warrants (in
each case after  giving  effect to the  Acquisition;  provided  that for periods
prior to the Effective Date, the  representations and warranties with respect to
ARDIS are made to the  Borrower's and the Parent  Guarantor's  best knowledge in
reliance on the  representations and warranties in the ARDIS Purchase Agreement)
that,  except as set forth in the  section (if any) of the  Disclosure  Schedule
corresponding to the Section heading below:

     SECTION 4.01.  Corporate Existence and Power. Each of the Parent Guarantor,
the  Borrower,   and  each  of  its  Principal  Subsidiaries  and  Subsidiaries,
respectively,  (a) is a corporation duly  incorporated,  validly existing and in
good standing under the laws of the jurisdiction of its  incorporation;  (b) has
the power and authority and all material governmental licenses,  authorizations,
consents and approvals  required to carry on its business as now conducted;  (c)
is duly qualified as a foreign corporation,  licensed and in good standing under
the  laws of each  jurisdiction  where  its  ownership,  lease or  operation  of
property or the conduct of its business requires such qualification;  and (d) is
in compliance with all  Requirements  of Law except,  in the case of clauses (c)
and (d),  where  the  failure  to be so  qualified  or in  compliance  could not
reasonably be expected to have a Material Adverse Effect.

     SECTION 4.02.  Corporate  Authorization;  No Contravention.  The execution,
delivery and performance by each of the Parent Guarantor and its Subsidiaries of
any Loan  Document  to which it is a party  have  been  duly  authorized  by all
necessary  corporate action and do not and will not: (a) contravene the terms of
such  Person's  certificate  of  incorporation,  bylaws  or  other  organization
document;  (b) conflict with or result in any breach or contravention of, or the
creation  of any  Lien  under,  any  indenture,  agreement,  lease,  instrument,
Contractual Obligation,  injunction,  order, decree or undertaking to which such
Person is a party; or (c) violate any Requirement of Law.

     SECTION  4.03.  Government  Approvals.  All material  Government  Approvals
heretofore required to be obtained have been duly obtained, were validly issued,
are in full force and effect, are not subject to appeal and are held in the name
of, or for the  benefit  of, the  appropriate  Persons.  There is no  proceeding
pending  or, to the best  knowledge  of the  Borrower  or the Parent  Guarantor,
threatened  against  the Parent  Guarantor  or any of its  Subsidiaries,  or any
property of the Parent Guarantor or any of its Subsidiaries, which seeks, or may
reasonably be expected,  to rescind,  terminate,  materially adversely modify or
suspend any of the FCC  Licenses.  There has not  occurred  any event that would



                                       34

<PAGE>


make unlikely the delivery or issuance as anticipated of, and when and as needed
all such Government  Approvals.  No such Government Approval already obtained is
subject to any restriction,  condition, limitation or other provision that would
have a Material  Adverse Effect.  The information set forth in each  application
submitted  by the Parent  Guarantor,  the  Borrower  or any of their  respective
Subsidiaries in connection  with each such  Government  Approval is accurate and
complete in all material  respects  taken as a whole,  except for  statements or
omissions  which  could not  reasonably  be  expected  to affect  adversely  the
validity of such Government  Approvals.  No other material consent,  approval or
authorization of, or declaration or filing with, any other Person is required in
connection with the execution, delivery, performance, validity or enforceability
of this Agreement or any other Loan Document.

     SECTION 4.04.  Binding Effect.  This Agreement and each other Loan Document
to which the Parent  Guarantor or any of its  Subsidiaries is a party constitute
the legal,  valid and binding  obligations of such Person,  enforceable  against
such Person in accordance with their respective terms,  except as enforceability
may be limited by applicable bankruptcy,  insolvency,  or similar laws affecting
the  enforcement  of  creditors'  rights  generally or by  equitable  principles
relating to enforceability.

     SECTION 4.05.  Litigation.  Except for matters  arising after the Effective
Date which could not reasonably be expected to have a Material  Adverse  Effect,
there are no actions, suits, proceedings,  claims or disputes pending, or to the
best  knowledge  of  the  Parent  Guarantor  or  the  Borrower,   threatened  or
contemplated  at law,  in equity,  in  arbitration  or before  any  Governmental
Authority,  against the Parent  Guarantor or any of its  Subsidiaries  or any of
their  respective  properties  which:  (a)  purport to affect or pertain to this
Agreement, or any Loan Document, or any of the transactions  contemplated hereby
or thereby; or (b) if determined adversely to the Parent Guarantor or any of its
Subsidiaries,  could  have a  Material  Adverse  Effect.  No  injunction,  writ,
temporary  restraining  order or any order of any nature has been  issued by any
court or other  Governmental  Authority  purporting  to enjoin or  restrain  the
execution,  delivery  and  performance  of  this  Agreement  or any  other  Loan
Document,  or directing that the transactions provided for herein or therein not
be consummated as herein or therein provided.

     SECTION  4.06. No Default.  No Default or Event of Default  exists or would
result from the incurring of Obligations  by the Parent  Guarantor or any of its
Subsidiaries  under any Loan Document.  Neither the Parent  Guarantor nor any of
its  Subsidiaries  is in  default  under  or  with  respect  to any  Contractual
Obligation  in any  respect  which,  individually  or  together  with  all  such
defaults, could have a Material Adverse Effect.


                                       35

<PAGE>



     SECTION 4.07. ERISA Compliance. (a) Section 4.07 of the Disclosure Schedule
lists all Plans  maintained or sponsored by the Parent Guarantor or the Borrower
or to which either of them is obligated to contribute, and separately identifies
Plans  intended  to be  Qualified  Plans and  Multiemployer  Plans.  All written
descriptions  thereof  provided  to the  Agents  are  true and  complete  in all
material respects.  Each Plan is in compliance in all material respects with the
applicable  provisions  of  ERISA,  the Code and  other  Federal  or state  law,
including all requirements under the Code or ERISA for filing reports (which are
true and correct in all material  respects as of the date  filed),  and benefits
have been paid in accordance  with the  provisions of the Plan.  Each  Qualified
Plan has been  determined  by the IRS to qualify  under Section 401 of the Code,
and to the best knowledge of the Parent  Guarantor and the Borrower  nothing has
occurred which would cause the loss of such qualification.

     (b) There is no outstanding  liability under Title IV of ERISA with respect
to any Plan maintained or sponsored by any member of the Controlled Group (as to
which the  Parent  Guarantor  or the  Borrower  is or may be  liable),  nor with
respect to any Plan to which any member of the Controlled  Group  contributes or
is obligated to contribute  (wherein the Parent  Guarantor or the Borrower is or
may be liable).  No Plan maintained or sponsored by the Parent  Guarantor or the
Borrower provides medical or other welfare benefits or extends coverage relating
to such benefits  beyond the date of a  participant's  termination of employment
with the Parent Guarantor or Borrower,  except to the extent required by Section
4980B of the Code and at the sole expense of the  participant or the beneficiary
of the participant to the fullest extent  permissible  under such Section of the
Code. Each of the Parent Guarantor and the Borrower has complied in all material
respects with the notice and continuation coverage requirements of Section 4980B
of the Code.

     (c) No ERISA  Event has  occurred or is  reasonably  expected to occur with
respect to any Plan  maintained  or  sponsored  by the Parent  Guarantor  or the
Borrower  or to which the Parent  Guarantor  or the  Borrower  is  obligated  to
contribute.  There  are no  pending  or,  to the best  knowledge  of the  Parent
Guarantor and the Borrower,  threatened claims, actions or lawsuits,  other than
routine  claims for  benefits  in the usual and  ordinary  course,  asserted  or
instituted  against (i) any Plan maintained or sponsored by the Parent Guarantor
or the  Borrower or its  assets,  (ii) any member of the  Controlled  Group with
respect to any Qualified Plan of the Parent Guarantor or the Borrower,  or (iii)
any  fiduciary  with  respect to any Plan for which the Parent  Guarantor or the
Borrower  may  be  directly  or  indirectly  liable,   through   indemnification
obligations  or  otherwise.  Neither the Parent  Guarantor  nor the Borrower has
incurred  or  reasonably  expects to incur (i) any  liability  (and no event has
occurred  which,  with the giving of notice under  Section 4219 of ERISA,  would



                                       36

<PAGE>


result  in such  liability)  under  Section  4201 of  ERISA  with  respect  to a
Multiemployer  Plan or (ii) any  liability  under Title IV of ERISA  (other than
premiums due and not  delinquent  under Section 4007 of ERISA) with respect to a
Plan. Neither the Parent Guarantor nor the Borrower has transferred any Unfunded
Pension  Liability  outside of the  Controlled  Group or otherwise  engaged in a
transaction that could be subject to Section 4069 or 4212(c) of ERISA.

     (d) Neither the Parent Guarantor nor the Borrower has engaged,  directly or
indirectly,  in a non-exempt prohibited  transaction (as defined in Section 4975
of the  Code or  Section  406 of  ERISA)  in  connection  with any  Plan,  which
transaction could have a Material Adverse Effect.

     SECTION  4.08.  Title to  Property.  Each of the Parent  Guarantor  and its
Principal Subsidiaries and the Borrower and its Subsidiaries has good record and
marketable  title in fee  simple  to or valid  leasehold  interests  in all real
property  used in its  business,  except for such defects in title as could not,
individually  or in the aggregate,  have a Material  Adverse  Effect.  Such real
property  is free and clear of all Liens or rights of others,  except  Permitted
Liens.

     SECTION  4.09.  Taxes.  Each of the  Parent  Guarantor  and  its  Principal
Subsidiaries  and the Borrower and its  Subsidiaries  have filed all Federal and
other  material  tax returns and reports  required to be filed and have paid all
Federal  and other  material  taxes,  assessments,  fees and other  governmental
charges  levied  or  imposed  upon  them or their  properties,  income or assets
otherwise due and payable  except those which are being  contested in good faith
by appropriate proceedings and for which adequate reserves have been provided in
accordance with GAAP and no Notice of Lien has been filed or recorded.  There is
no  proposed  tax  assessment  against  the  Parent  Guarantor  or  any  of  its
Subsidiaries  which would, if the assessment were made, have a Material  Adverse
Effect.

     SECTION 4.10. Financial Condition.

     (a) The audited consolidated statements of financial position of the Parent
Guarantor  and its  Subsidiaries  dated  December  31,  1996,  and  the  related
consolidated  statements  of loss,  stockholders'  equity and cash flows for the
fiscal  year ended on that  date:  (i) were  prepared  in  accordance  with GAAP
consistently applied throughout the periods covered thereby, except as otherwise
expressly noted therein,  (ii) fairly  present,  in all material  respects,  the
financial  condition of the Parent Guarantor and its Subsidiaries as of the date
thereof and results of operations for the period covered  thereby and (iii) show
all material  Indebtedness and other liabilities,  direct or contingent,  of the
Parent  Guarantor  and its  consolidated  Subsidiaries  as of the  date  thereof
(including liabilities for taxes and material commitments).



                                       37

<PAGE>




     (b) The unaudited pro forma summary consolidated condensed balance sheet of
the Parent Guarantor and its Subsidiaries as of September 30, 1997 together with
the related pro forma summary  condensed  statement of  operations  data for the
nine months then ended  fairly  present,  in  conformity  with GAAP applied on a
basis  consistent  with the financial  statements  referred to in subsection (a)
above,  the  consolidated  financial  position of the Parent  Guarantor  and its
Subsidiaries as of such date, based on the assumptions set forth therein.  As of
such date and the Closing Date, the Parent  Guarantor and its  Subsidiaries  had
and  have no  material  liabilities,  contingent  or  otherwise,  which  are not
properly  reflected on such balance sheet  (including  liabilities for taxes and
material commitments).

     (c) Since September 30, 1997, there has been no Material Adverse Effect.

     SECTION 4.11. Environmental Matters. The operations of the Parent Guarantor
and  each  of  its  Subsidiaries  comply  in  all  material  respects  with  all
Environmental  Laws.  The Parent  Guarantor  and each of its  Subsidiaries  have
obtained all licenses, permits,  authorizations and registrations required under
any Environmental Law ("Environmental  Permits") necessary for its operations to
comply  in  all  material  respects  with  Environmental   Laws,  and  all  such
Environmental Permits are in full force and effect, and the Parent Guarantor and
each  of  its  Subsidiaries  are in  material  compliance  with  all  terms  and
conditions of such Environmental  Permits. None of the Parent Guarantor,  any of
its  Subsidiaries  or any of their  present or, to the  knowledge  of the Parent
Guarantor  and the  Borrower,  past  property  or  operations  is subject to any
outstanding  written order from or agreement with any Governmental  Authority or
other  Person,  nor  subject  to  any  judicial  or  administrative  proceeding,
respecting any Environmental  Law,  Environmental  Claim or Hazardous  Material.
There  are  no  conditions  or   circumstances   which  may  give  rise  to  any
Environmental  Claim arising from the operations of the Parent  Guarantor or its
Subsidiaries,  including  Environmental Claims associated with any operations of
the Parent Guarantor or its Subsidiaries,  with a potential  liability in excess
of  $5,000,000  in  the  aggregate.  Without  limiting  the  generality  of  the
foregoing,  the Parent Guarantor and its Subsidiaries  have met all notification
requirements under Title III of the Superfund Amendments and Reauthorization Act
of 1986 or any other Environmental Law.

     SECTION 4.12. Regulated Entities. None of the Parent Guarantor,  any Person
controlling  the  Parent  Guarantor,  or  any  Subsidiary  thereof,  is  (a)  an
"Investment  Company" within the meaning of the Investment  Company Act of 1940;




                                       38

<PAGE>


or (b) subject to regulation  under the Public  Utility  Holding  Company Act of
1935,  the Federal  Power Act,  the  Interstate  Commerce  Act, any state public
utilities code or any other Federal or state statute or regulation  limiting its
ability to incur Indebtedness.

     SECTION 4.13.  Subsidiaries.  As of the Closing Date, the Borrower does not
have any Subsidiaries and has no equity  investments in any other corporation or
entity.

     SECTION  4.14.   Insurance.   The   properties  of  the  Borrower  and  its
Subsidiaries  are  insured  with  financially  sound  and  reputable   insurance
companies,  in such amounts, with such deductibles and covering such risks as is
customarily  carried on by companies  engaged in similar  businesses  and owning
similar properties in localities where the Borrower or such Subsidiary operates.

     SECTION  4.15.  Business.  The  Borrower  and  its  Subsidiaries  have  not
conducted  any business  other than as  described  in the  Offering  Memorandum.
Neither the business nor the properties of the Borrower and its Subsidiaries are
or have been affected by any fire, explosion, accident, strike, lockout or other
labor dispute,  drought, storm, hail, earthquake,  embargo, act of God or of the
public enemy or other casualty  (whether or not covered by insurance)  which has
had a Material Adverse Effect.

     SECTION 4.16. Disclosure.  The information (including,  without limitation,
the information in the Offering Memorandum)  furnished in writing at or prior to
the Closing Date by the Parent Guarantor or the Borrower to any Agent or Bank in
connection with this Agreement and the transactions contemplated hereby is true,
complete and accurate in every material respect or based on reasonable estimates
on the date as of which  such  information  is  stated or  certified  and is not
incomplete  by  omitting  to state  any  material  fact  necessary  to make such
information  (taken as a whole)  not  misleading  in light of the  circumstances
under  which such  information  was made.  The pro forma  financial  projections
contained in the Offering Memorandum were made in good faith and the assumptions
on the basis of which such projections were made were (when made) and are (as of
the date of this  Agreement)  reasonable.  There is no fact  known to the Parent
Guarantor  or the  Borrower  on the date as of  which  this  representation  and
warranty is made that has not been disclosed in writing to the Agent which could
reasonably be expected to have a Material Adverse Effect.



                                       39

<PAGE>



                                    ARTICLE 5
                                    COVENANTS

     Each of the Borrower and the Parent  Guarantor  agrees that, so long as any
Bank has any Commitment  hereunder or any amount payable  hereunder or under any
Note remains unpaid:

     SECTION 5.01. Information. The Borrower will deliver to each of the Banks:

     (a) as soon as available,  but not later than 90 days after the end of each
fiscal year of the Borrower and the Parent Guarantor,  respectively,  commencing
with  the  fiscal  year  ending  December  31,  1997,  a  copy  of  the  audited
consolidated  balance sheets of the Borrower and the Parent  Guarantor as at the
end of such year and the  related  audited  consolidated  statements  of income,
stockholders'  equity and cash flows for such fiscal year, setting forth in each
case in comparative  form the figures for the previous year, and  accompanied by
the opinion of Arthur Andersen LLP or another nationally-recognized  independent
public accounting firm which report shall state that such consolidated financial
statements  present fairly, in all material  respects,  the financial  position,
results of  operations  and cash flows for the periods  indicated in  conformity
with GAAP applied on a basis consistent with prior years;

     (b) as soon as available,  but not later than 45 days after the end of each
of the first three fiscal quarters of each year,  commencing with the first such
fiscal  quarter  to end  after  the  Effective  Date,  a copy  of the  unaudited
consolidated  balance sheets of the Borrower and Parent  Guarantor as of the end
of such quarter and the related consolidated statements of income, stockholders'
equity and cash flows for the period  commencing  on the first day and ending on
the  last day of such  quarter,  and  certified  by an  appropriate  Responsible
Officer as fairly presenting,  in all material respects, in accordance with GAAP
(except for the absence of footnote disclosure),  the financial position and the
results of operations of the Borrower and the Parent Guarantor; and

     (c) as soon as  available,  any other interim  financial  statements of the
Borrower and its Subsidiaries  reasonably  requested by the Administrative Agent
at the direction of the Required Banks.

     SECTION 5.02. Certificates; Other Information. The Borrower will deliver to
each of the Banks:

     (a) concurrently with the delivery of the financial  statements referred to
in Section  5.01(a)  above, a certificate of the  independent  certified  public


                                       40

<PAGE>



accountants  reporting on such financial  statements  stating that in making the
examination necessary therefor no knowledge was obtained of any Default or Event
of Default, except as specified in such certificate;

     (b) concurrently with the delivery of the financial  statements referred to
in Section 5.01(a) above, a certificate of a Responsible Officer of the Borrower
(i) stating that, to the best of such officer's knowledge, the Borrower,  during
such  period,  has  observed  or  performed  all  of  its  covenants  and  other
agreements,  and satisfied  every  condition  contained in this  Agreement to be
observed,  performed  or  satisfied by it, and that such officer has obtained no
knowledge  of any  Default  or Event of  Default  except  as  specified  in such
certificate, (ii) when applicable, showing in detail the calculations supporting
such  statement in respect of Article 5 and (iii)  setting forth the Excess Cash
Flow for such  period,  together  with the  calculation  thereof  in  reasonable
detail;

     (c)  promptly  after  the same are  filed,  copies  of (if,  in the case of
reports to the FCC,  such reports are material)  all  financial  statements  and
regular,  periodical or special reports which the Borrower, the Parent Guarantor
or any  Subsidiary  of the  Parent  Guarantor  may make to,  or file  with,  the
Securities  and  Exchange  Commission,  the  FCC or  any  successor  or  similar
Governmental Authorities; and

     (d)  promptly,  such  additional  financial  and other  information  as the
Administrative  Agent,  at the  request  of any  Bank,  may  from  time  to time
reasonably request.

     SECTION 5.03.  Notices.  The Borrower shall promptly  notify the Agents and
each Bank of:

     (a)  the  occurrence  of  any  Default  or  Event  of  Default,  and of the
occurrence or existence of any event or  circumstance  that could  reasonably be
expected to become a Default or Event of Default;

     (b)  any (i)  breach  or  non-performance  of,  or any  default  under  any
Contractual  Obligation  which  could  reasonably  be  expected  to  result in a
Material Adverse Effect; or (ii) dispute, litigation, investigation,  proceeding
or suspension which may exist at any time between the Parent Guarantor or any of
its  Subsidiaries  and any  Governmental  Authority  and  which,  if  determined
adversely to the Parent Guarantor or any of its  Subsidiaries,  could reasonably
be expected to result in a Material Adverse Effect;

     (c) the commencement of, or any material  development in, any litigation or
proceeding  affecting the Parent  Guarantor or any  Subsidiary  (i) in which the
amount of  damages claimed is  $5,000,000 (or its equivalent in another currency

                                       41

<PAGE>




or currencies) or more, (ii) in which injunctive or similar relief is sought and
which, if adversely  determined,  could have a Material Adverse Effect, or (iii)
in which the relief sought is an injunction or other stay of the  performance of
any Loan  Document  or the  operations  of the  Parent  Guarantor  or any of its
Subsidiaries;

     (d) upon, but in no event later than ten days after,  becoming aware of (i)
any and all enforcement,  cleanup,  removal or other  governmental or regulatory
actions instituted,  completed or threatened against the Parent Guarantor or any
Subsidiary or any of their properties  pursuant to any applicable  Environmental
Laws, (ii) all other Environmental  Claims or (iii) any environmental or similar
condition on any real  property  adjoining or in the vicinity of the property of
the  Parent  Guarantor  or any of its  Subsidiaries  that  could  reasonably  be
anticipated  to cause  such  property  or any part  thereof to be subject to any
restrictions  on the  ownership,  occupancy,  transferability  or  use  of  such
property under any Environmental Laws;

     (e) any other  litigation or proceeding  affecting the Parent  Guarantor or
any of its  Subsidiaries  which the Parent Guarantor would be required to report
to the Securities and Exchange  Commission  pursuant to the Securities  Exchange
Act of 1934,  within four days after  reporting the same to the  Securities  and
Exchange Commission;

     (f) any ERISA Event  affecting the Borrower or any member of its Controlled
Group (but in no event more than ten days after such ERISA Event)  together with
(i) a copy of any notice  with  respect to such ERISA  Event filed with the PBGC
and (ii) any notice  delivered  by the PBGC to the Borrower or any member or its
Controlled Group with respect to such ERISA Event;

     (g) any Material  Adverse Effect  subsequent to the date of the most recent
audited financial  statements of the Borrower delivered to the Banks pursuant to
Section 5.01(a);

     (h) any  material  change in  accounting  policies or  financial  reporting
practices;

     (i) any labor  controversy  resulting  in or  threatening  to result in any
strike,  work stoppage,  boycott,  shutdown or other labor disruption against or
involving the Borrower or any Subsidiary;

     (j) any material revision of the Borrower's business plan;

     (k) the adoption of each capital expenditures budget by the Borrower;


                                       42

<PAGE>



     (l) any event  that  could  reasonably  be  expected  to result in Net Cash
Proceeds requiring a mandatory prepayment pursuant to Section 2.09; and

     (m) the  delivery  of, or  receipt  of, any  notice of (i) a  reduction  in
coverage of any insurance required to be maintained by Section 5.06 or otherwise
procured by the Borrower covering loss or damage to any material property of the
Borrower (other than a reduction in coverage or amount  resulting from a payment
thereunder)  or (ii) the  cancellation  or  non-renewal  of any  such  insurance
policy.

Each  notice  pursuant  to this  Section  shall be  delivered  promptly  after a
Responsible Officer becomes aware of the subject matter of such notice and shall
be accompanied by a written  statement by a Responsible  Officer of the Borrower
setting forth details and effective date of the  occurrence  referred to therein
and stating what action the Borrower proposes to take with respect thereto.

     SECTION 5.04.  Conduct of Business;  Preservation  of Corporate  Existence.
Each of the Parent Guarantor and the Borrower shall, and shall cause each of its
Principal Subsidiaries and Subsidiaries, respectively: (a) to engage in business
of the same  general  type as now  conducted  by the  Parent  Guarantor  and its
Subsidiaries  (including  ARDIS  and  AMRC  Holdings  and  Subsidiaries  of AMRC
Holdings);  (b) to preserve and maintain in full force and effect its  corporate
existence  and good  standing  under  the laws of its State or  jurisdiction  of
incorporation; (c) to preserve and maintain in full force and effect all rights,
privileges,  qualifications,  permits,  licenses  and  franchises  necessary  or
desirable  in the normal  conduct  of its  business;  (d) to use its  reasonable
efforts,  in the ordinary course and consistent with past practice,  to preserve
its  business  organization  and  preserve  the  goodwill  and  business  of the
customers,  suppliers and others having  business  relations with it; and (e) to
preserve  or renew all of its  registered  trademarks,  trade  names and service
marks, the non-preservation of which could have a Material Adverse Effect.

     SECTION 5.05. Maintenance of Property.  Each of the Borrower and the Parent
Guarantor shall maintain, and shall cause each of its Principal Subsidiaries and
Subsidiaries,  respectively, to maintain, and preserve all its property which is
used or useful in its business in good  working  order and  condition,  ordinary
wear and tear excepted.

     SECTION 5.06.  Maintenance of Insurance.  (a) The Borrower shall procure at
its own expense and  maintain in full force and effect at all times on and after
the Effective Date with responsible  insurance  carriers with a Best's rating of



                                       43

<PAGE>


A/VII or better  (except  for  policies  underwritten  by  Lloyds of London  and
companies  acceptable  to the  Agents and the  Required  Banks),  the  following
insurance:

                    (i) Workers' Compensation Insurance:  Except as to exposures
                    in those  jurisdictions in which the state government is the
                    sole source of such  insurance,  as  required by  applicable
                    state  laws  including,   without   limitation,   employer's
                    liability insurance with the following limits: bodily injury
                    by  accident:  $100,000  each  accident;  bodily  injury  by
                    disease:  $100,000  each  employee;  and  bodily  injury  by
                    disease: $500,000 policy limit (the policies with respect to
                    which shall include an all states' endorsement).

                    (ii)  Commercial  General  Liability:   Against  claims  for
                    personal  injury  (including  bodily  injury  and death) and
                    property damage in such amounts as are  customarily  carried
                    by companies of established  repute engaged in the same or a
                    similar  business  but  not  to  exceed  $5,000,000  in  the
                    aggregate.   Such  insurance  shall  provide   coverage  for
                    products/completed    operations,    blanket    contractual,
                    explosion,  collapse and  underground  coverage,  broad form
                    property   damage  and  personal   injury   insurance   with
                    $1,000,000 each  occurrence,  $1,000,000  general  aggregate
                    (other  than  products/completed   operations),   $1,000,000
                    personal   and    advertising    limit,    and    $1,000,000
                    products/completed operations aggregate limit.

                    (iii)  Business  Automobile  Liability:  Against  claims for
                    personal  injury  (including  bodily  injury  and death) and
                    property  damage covering all owned,  leased,  non-owned and
                    hired motor  vehicles (to the extent there are any thereof),
                    with a $2,000,000  minimum limit per occurrence for combined
                    bodily injury and property damage and in the aggregate where
                    applicable.

                    (iv)  Business   Interruption   Insurance:   To  the  extent
                    reasonably  obtainable on customary terms and conditions and
                    with customary exclusions,  with respect to any risk of loss
                    in respect of which the  Borrower in its  judgment  does not
                    then have  adequate  redundant  or  replacement  property or
                    assets   available   which   would   prevent   any  loss  or
                    interruption  of  any  cash  flow  if  such  loss  occurred,
                    business  interruption  insurance with a $2,000,000  minimum
                    limit per occurrence.

                    (v) Property Damage Insurance: (x) Property damage insurance
                    on an  "all  risk"  basis  (with  customary  conditions  and
                    exclusions) including coverage against damage or loss caused
                    by earth  movement and flood and providing  coverage for its



                                       44

<PAGE>


                    satellites and  communications  ground segment (the "Covered
                    Property"),  in a  minimum  aggregate  amount  equal  to the
                    lesser of (1) the  "full  insurable  value"  of the  Covered
                    Property and (2) 110% of all Obligations and (y) unless both
                    of the Agents shall otherwise agree, In-Orbit Insurance. For
                    purposes  of this  clause  (v) and  Section  5.06(b),  "full
                    insurable  value" shall mean the full  replacement  value of
                    the  Covered   Property,   including  any  improvements  and
                    equipment  and  supplies,  without  deduction  for  physical
                    depreciation and/or obsolescence; all such policies may have
                    deductibles of not greater than  $250,000,  except for earth
                    movement  insurance which will have the lowest deductible as
                    shall  (in  the  opinion  of the  Agents)  be  available  on
                    commercially reasonable terms in the insurance market place.
                    Such insurance shall include an "agreed amount" clause.  For
                    purposes of this clause (v), "In-Orbit Insurance" shall mean
                    in-orbit  insurance,  with insurance carriers  acceptable to
                    the  Agents,   in  a  minimum   aggregate  amount  equal  to
                    $184,000,000  and when the ACTEL Lease Agreement and the TMI
                    Purchase  Agreement become effective an additional amount of
                    in-orbit insurance of $50,000,000 shall be obtained to cover
                    MSAT-1  and  up  to  $50,000,000  of  such  $184,000,000  of
                    insurance  on MSAT-2 may be for the  account  and benefit of
                    ACTEL or other  lessee under a Satellite  Lease  Arrangement
                    (or if  coverage  in  such  amounts  is  unavailable  to the
                    Borrower  using its  reasonable  best  efforts,  such lesser
                    amounts  as the  Borrower  is able  to  obtain)  and  having
                    deductibles and other terms and conditions as are reasonably
                    available  in  the  market  at   reasonable   cost  and  are
                    acceptable to the Agents.

     (b) All  policies  of  insurance  required  to be  maintained  pursuant  to
Sections  5.06(a)(iv)  and  5.06(a)(v)  or  otherwise  procured by the  Borrower
covering loss or damage to any of the Borrower's property shall provide that (i)
there  shall be no  recourse  against  the  Agents or the Banks for  payment  of
premiums or other amounts with respect  thereto,  (ii) to the extent  available,
the insurer is required  to provide  the  Administrative  Agent with at least 30
days (or ten days, in the case of nonpayment of premiums)  prior written  notice
of reduction in coverage or amount (other than a reduction in coverage or amount
resulting from a payment thereunder),  cancellation or non-renewal of any policy
and (iii) the proceeds of all policies  (other than in respect of  comprehensive
general liability,  workers' compensation and comprehensive automobile liability
insurance)  shall be payable to the  Administrative  Agent  pursuant to standard
first mortgagee endorsement,  without contribution,  substantially equivalent to
the New York standard mortgagee  endorsement.  If the Borrower fails or may fail
to timely file any proof of loss, the Administrative  Agent shall have the right
to join the  Borrower in  submitting  a proof of any loss in excess of $250,000.
All such  policies  (other than in respect of workers'  compensation  insurance)
shall insure the interests of the Insured Parties, as their interest may appear,




                                       45

<PAGE>


and shall  further  provide,  to the extent such  insurance  is  available  at a
commercially  reasonable rate, that payments shall be made thereunder regardless
of any breach or  violation  by the  Borrower  of  warranties,  declarations  or
conditions  not  contained  in such  policies,  any  action or  inaction  of the
Borrower  (other than  nonpayment  of  premiums) or others,  or any  foreclosure
relating to its satellite or communications ground segment or any other business
of the  Borrower or any change in  ownership of all or any portion of thereof or
any other  business of the  Borrower.  Each such policy  shall (i) except in the
case of insurance required to be maintained pursuant to Sections 5.06(a)(iv) and
5.06(a)(v),  waive  any  right of  subrogation  against  the  Banks  (and  their
respective officers, employees and agents), (ii) except in the case of insurance
required  to be  maintained  pursuant to Sections  5.06(a)(iv)  and  5.06(a)(v),
include a severability of interest or cross liability clause, (iii) provide that
the insurance be primary and not excess of or  contributory  to any insurance or
self-insurance maintained by the Borrower, the Agents or the Banks, (iv) contain
a breach of warranty  clause in favor of the Agents and the Banks and (v) except
in the case of workers'  compensation  insurance,  name the  Insured  Parties as
their interests may appear, as additional insureds or loss payees.

     (c) The Borrower shall deliver to the Administrative  Agent, within 30 days
after the close of each  fiscal  year,  commencing  with the fiscal  year ending
December  31,  1998,  a  certificate  of  International  Space  Brokers,   Inc.,
Metro/Risk,  Inc. or other recognized independent insurance brokers,  reasonably
acceptable to the Required  Banks,  (i) confirming  that all insurance  policies
required  pursuant to this Section 5.06 are in force on the date  thereof,  (ii)
confirming the names of the companies  issuing such policies,  (iii)  confirming
the  amounts  and  expiration  date or dates of such  policies,  (iv)  including
certificates  evidencing  such policies marked "premium paid" for the prior year
and (v) stating that in such  broker's  opinion  after due  investigation,  such
policies substantially comply with the requirements of this Section 5.06.

     (d) In the event the Borrower  fails to take out or  maintain,  or fails to
cause to be taken out or  maintained,  the full insurance  coverage  required by
this Section 5.06, the Administrative  Agent (upon the direction of the Required
Banks),  upon 30 days' prior notice (unless the  aforementioned  insurance would
lapse  within  such  period,  in which event  notice  should be given as soon as
reasonably  possible) to the Borrower of any such failure, may (but shall not be
obligated  to) take out the required  policies of insurance and pay the premiums
on the same. All amounts so advanced therefor by the Administrative  Agent shall
be immediately  reimbursed by the Borrower to the Administrative  Agent, and the
Borrower shall forthwith pay such amounts to the Administrative  Agent, together
with  interest  thereon at the sum of 2% plus the rate  otherwise  applicable to
Base Rate Loans for each day until paid.


                                       46

<PAGE>




     (e) The  Administrative  Agent  shall  promptly  notify  each  Bank of each
written notice  received by it with respect to the  cancellation  of or material
adverse change in any insurance policy required to be maintained by the Borrower
pursuant to this Section 5.06.

     SECTION 5.07. Payment of Obligations.  Each of the Parent Guarantor and the
Borrower  shall,  and  shall  cause  each  of  its  Principal  Subsidiaries  and
Subsidiaries,  respectively,  to, pay and discharge as the same shall become due
and  payable,  all  its  obligations  and  liabilities,  including:  (a) all tax
liabilities,  assessments  and  governmental  charges  or levies  upon it or its
properties  or  assets,  unless  the same are being  contested  in good faith by
appropriate  proceedings and adequate reserves in accordance with GAAP are being
maintained by such Person; (b) all lawful claims which, if unpaid,  might by law
become a Lien upon its property  (excluding claims being contested in good faith
by the Borrower,  and for which adequate  reserves have been made or as to which
the corresponding liens have been bonded);  and (c) all Indebtedness as and when
due and payable but subject to any  subordination  provisions  contained  in any
instrument or agreement evidencing such Indebtedness.

     SECTION 5.08.  Compliance with Laws.  Each of the Parent  Guarantor and the
Borrower shall comply,  and shall cause each of its Principal  Subsidiaries  and
Subsidiaries,  respectively,  to  comply,  in all  material  respects  with  all
Requirements of Law of any Governmental Authority having jurisdiction over it or
its business (including the Federal Fair Labor Standards Act and ERISA),  except
such as may be  contested  in good faith or as to which a bona fide  dispute may
exist.

     SECTION  5.09.  Inspection  of Property and Books and Records.  Each of the
Parent  Guarantor and the Borrower shall  maintain,  and shall cause each of its
Principal Subsidiaries and Subsidiaries, respectively, to maintain, proper books
of record and account,  in which full,  true and correct  entries in  conformity
with GAAP consistently  applied shall be made of all financial  transactions and
matters  involving  the assets and  business  of the  Parent  Guarantor  and the
Borrower and such Principal  Subsidiaries.  Each of the Parent Guarantor and the
Borrower  will permit,  and will cause each of its  Principal  Subsidiaries  and
Subsidiaries,  respectively, to permit,  representatives of any Agent or Bank to
visit and inspect any of its properties, to examine its corporate, financial and
operating records and make copies thereof or abstracts therefrom, and to discuss
its affairs, finances and accounts with its directors,  officers,  employees and
independent  public  accountants at such reasonable times during normal business
hours and as often as may be reasonably desired,  upon reasonable advance notice
to the Parent Guarantor or the Borrower,  as the case may be; provided that when




                                       47

<PAGE>


an Event of Default exists representatives from the United States offices of any
Agent  or Bank may  visit  and  inspect  at the  expense  of the  Borrower  such
properties at any time during  business hours and without  advance  notice.  The
Borrower shall reimburse the Agents and the Banks for their reasonable  expenses
incurred in  conducting  such visits and  examinations  when an Event of Default
exists.

     SECTION 5.10.  Environmental Laws. (a) Each of the Parent Guarantor and the
Borrower shall, and shall cause each of its respective  Subsidiaries to, conduct
its  operations  and keep and  maintain  its  property  in  compliance  with all
Environmental Laws.

     (b) Upon written  request of any Agent or Bank,  the Borrower  shall submit
and cause  each of its  Subsidiaries  to submit,  to such Agent or Bank,  at the
Borrower's sole cost and expense at reasonable intervals,  a report providing an
update of the  status  of and any  environmental,  health  or safety  compliance
obligation, remedial obligation or liability, that could, individually or in the
aggregate, result in liability in excess of $5,000,000.

     SECTION 5.11.  Use of Proceeds.  The Borrower shall use the proceeds of the
Loans only for general corporate  purposes,  including capital  expenditures and
the  refinancing of  obligations  under the Hughes Bridge Loan Agreement and the
Existing Credit  Facilities.  No portion of the Loans will be used,  directly or
indirectly,  for the purpose,  whether  immediate,  incidental  or ultimate,  of
buying or carrying any "margin  stock"  within the meaning of  Regulation  U. No
proceeds  of any Loans will be used to acquire any  security in any  transaction
which is subject to Section 13 or 14 of the Securities  Exchange Act of 1934, as
amended.

     SECTION 5.12. No Subsidiaries. The Borrower shall not have any Subsidiaries
or equity  investments in any other corporation or entity except as set forth on
Schedule 4.13.

     SECTION 5.13.  Government  Approvals.  The Borrower shall,  and shall cause
each of its Subsidiaries to, comply with the terms of and maintain in full force
and effect the FCC Licenses,  and all amendments  thereto,  and shall, and shall
cause each of its Subsidiaries to, obtain, maintain and comply with the terms of
all other  Government  Approvals which are necessary  under  applicable laws and
regulations in connection with the Borrower's or such Subsidiary's  business. No
such  Government  Approval  shall  be  subject  to any  restriction,  condition,
limitation or other provision that would have a Material Adverse Effect.

     SECTION  5.14.  Further  Assurances.  Each of the  Borrower  and the Parent
Guarantor  shall  ensure  that all  written  information,  exhibits  and reports



                                       48

<PAGE>


furnished  to the Banks do not and will not  contain any untrue  statement  of a
material  fact and do not and will not omit to state  any  material  fact or any
fact necessary to make the statements  contained therein not misleading in light
of the circumstances in which made, and will promptly disclose to the Agents and
the Banks and correct any defect or error that may be  discovered  therein or in
any Loan Document or in the execution, acknowledgment or recordation thereof.

     SECTION  5.15.  Limitation on Liens.  Neither the Parent  Guarantor nor the
Borrower shall, nor shall either permit any member of the Parent Guarantor Group
to, directly or indirectly,  make, create,  incur, assume or suffer to exist any
Lien upon or with  respect to any part of its  property  or assets,  whether now
owned  or  hereafter  acquired,  or offer  or  agree  to do so,  other  than the
following ("Permitted Liens"):

     (a) any Lien existing on the Effective Date securing  Indebtedness existing
on the Effective Date and identified on Schedule 5.15;

     (b) any  Lien in  favor  of the  Administrative  Agent  created  under  the
Security and Pledge Agreement (as defined in the Term Credit  Agreement) and any
Lien  in  favor  of the  Shareholder  Guarantors  pursuant  to  the  Shareholder
Guarantor Security Agreement;

     (c) Liens for taxes, fees,  assessments or other governmental charges which
are not  delinquent or remain  payable  without  penalty,  or to the extent that
non-payment  thereof is permitted by Section  5.07,  provided  that no Notice of
Lien has been filed or recorded;

     (d)  carriers',  warehousemen's,   mechanics',  landlords',  materialmen's,
repairmen's  or other similar  Liens arising in the ordinary  course of business
which do not  secure  Indebtedness  and are not  delinquent  or  remain  payable
without penalty;

     (e) Liens  (other  than any Lien  imposed by ERISA) on the  property of any
member of the Parent Guarantor Group incurred,  or pledges or deposits required,
in connection  with  workmen's  compensation,  unemployment  insurance and other
social security legislation;

     (f) Liens on the  property  of any  member of the  Parent  Guarantor  Group
securing (i) the performance of bids,  trade contracts  (other than for borrowed
money), leases, statutory obligations, and (ii) obligations on surety and appeal
bonds,  and (iii) other  obligations  of a like nature  incurred in the ordinary
course of  business  which do not secure  Indebtedness,  provided  that all such
Liens in the aggregate could not cause a Material Adverse Effect;


                                       49

<PAGE>




     (g) easements,  rights-of-way,  restrictions and other similar encumbrances
incurred in the ordinary  course of business  which,  in the aggregate,  are not
substantial in amount,  and which do not in any case materially detract from the
value of the property  subject thereto or interfere with the ordinary conduct of
the businesses of the Parent Guarantor Group;

     (h) Liens on any asset  which is the  subject of a capital  lease  securing
Indebtedness incurred or assumed for the purpose of financing all or any part of
the  cost of  acquiring  such  asset,  provided  that  (x)  such  Lien  attaches
concurrently with or within 30 days after the acquisition  thereof,  and (y) the
sum of the aggregate principal amount of such Indebtedness secured by such Liens
shall not exceed $15,000,000;

     (i) Liens on  contract  rights  under  subscriber  equipment  leases  sold,
pledged or  otherwise  transferred  pursuant to any bona fide  financing of such
leases;

     (j) Liens on property and assets of AMRC Holdings and its Subsidiaries; and

     (k) Liens to secure  Vendor  Financing  Indebtedness  permitted  by Section
5.23(k);  provided  that such Liens  cover only the  assets  acquired  with such
Vendor Financing Indebtedness.

     SECTION 5.16.  Disposition of Assets,  Consolidations and Mergers.  Neither
the Parent  Guarantor nor the Borrower shall,  nor shall it permit any member of
the Parent Guarantor Group to, directly or indirectly,  (i) sell, assign, lease,
convey,  transfer  or  otherwise  dispose  of  (whether  in one or a  series  of
transactions) any of its assets,  business or property  (including  accounts and
notes  receivable  (with  or  without  recourse)  and  equipment  sale-leaseback
transactions) or (ii) merge or consolidate with any other Person,  or enter into
any agreement to do any of the foregoing described in clauses (i) or (ii) except
for the following;  provided that immediately  after giving effect to any of the
following, no Default or Event of Default would exist:

     (a) sales, transfers, or other dispositions of inventory, or used, worn-out
or surplus  property,  or property of no further use to the Parent Guarantor and
its Subsidiaries, all in the ordinary course of business;

     (b) sales,  transfers,  or other  dispositions of equipment in the ordinary
course of business to the extent that such  equipment  is  exchanged  for credit




                                       50

<PAGE>


against the purchase price of similar  replacement  equipment or the proceeds of
such  sale  are  reasonably  promptly  applied  to the  purchase  price  of such
replacement equipment;

     (c) sales,  transfers,  or other  dispositions of communications  services,
capacity or equipment pursuant to the customer contracts  providing for the sale
of  communications  services,  capacity or equipment  in the ordinary  course of
business;

     (d)  sales,   transfers  or  other  dispositions   pursuant  to  bona  fide
sale-leaseback  financings in which the lease gives rise solely to Capital Lease
Obligations;  provided,  however,  that  any  such  sales,  transfers  or  other
dispositions are not permitted with any assets of the communications network;

     (e)  sales,  transfers,  or other  dispositions  of assets in the  ordinary
course of business having a fair market value not exceeding $500,000 per item or
$1,000,000 in the aggregate in any fiscal year (excluding  sales,  transfers and
dispositions  theretofore  approved in accordance  with the terms hereof in such
fiscal year);

     (f) sales,  transfers or other  dispositions of assets to Sales Corporation
to be used in  connection  with the  sales  and  marketing  of  services  of the
Borrower  and  having  a fair  market  value  not  exceeding  $5,000,000  in the
aggregate during the term of this Agreement;

     (g)  sales,  transfers  or other  dispositions  of  contract  rights  under
subscriber equipment leases pursuant to any bona fide financing of such leases;

     (h) non-exclusive licenses of technology and other intangible assets;

     (i)  sales of mobile  earth  terminals  and  related  equipment,  and other
inventory;

     (j) any  Subsidiary of the Borrower may merge,  consolidate or combine with
or into, or transfer  assets to the Borrower or one or more  Subsidiaries of the
Borrower;  provided  that with  respect to any such  transaction  involving  the
Borrower,  the Borrower shall be the continuing or surviving  corporation and if
any  such  transaction   shall  be  between  a  Subsidiary  and  a  wholly-owned
Subsidiary,  the  wholly-owned  Subsidiary  shall be the continuing or surviving
corporation;

     (k) any Subsidiary of the Borrower may sell,  lease,  transfer or otherwise
dispose of any or all of its assets (upon  voluntary  liquidation or otherwise),
to the Borrower or another wholly-owned Subsidiary of the Borrower;


                                       51

<PAGE>




     (l) the Borrower or any Subsidiary  may merge,  consolidate or combine with
another  entity  if  the  Borrower  or  the  Subsidiary,  respectively,  is  the
corporation surviving the merger; and

     (m) the Satellite Lease Arrangements.

     SECTION  5.17.  Employee  Contracts  and  Arrangements.  Neither the Parent
Guarantor  nor  the  Borrower  shall,   nor  shall  either  permit  any  of  its
Subsidiaries  to,  enter into any  employment  contracts or  arrangements  whose
terms, including salaries,  benefits and other compensation,  are not normal and
customary  and   commercially   reasonable   for  companies  of  like  size  and
circumstances.

     SECTION 5.18.  Investments.  Neither of the Parent  Guarantor nor any other
member of the Parent  Guarantor Group will make or acquire any Investment in any
Person other than:

     (a) Investments in Persons which are Subsidiaries on the date hereof;

     (b) Cash Equivalents; and

     (c) any Investment not otherwise permitted by the foregoing clauses of this
Section if, immediately after such Investment is made or acquired, the aggregate
net book value of all  Investments  permitted by this clause (c) does not exceed
$10,000,000.

     SECTION 5.19. Transactions with Affiliates.  Except where such Affiliate is
a member of the Parent  Guarantor Group, the Parent Guarantor will not, and will
not permit any  Subsidiary to,  directly or indirectly,  (i) pay any funds to or
for the account of any  Affiliate,  (ii) make any  investment  in any  Affiliate
(whether by acquisition of stock or indebtedness,  by loan, advance, transfer of
property,  guarantee or other agreement to pay, purchase or service, directly or
indirectly,  any Indebtedness,  or otherwise),  (iii) lease,  sell,  transfer or
otherwise dispose of any assets,  tangible or intangible,  to any Affiliate,  or
(iv) participate in, or effect,  any transaction  with any Affiliate,  except in
each case on an arm's-length  basis on terms at least as favorable to the Parent
Guarantor or such Subsidiary as could have been obtained from a third party that
was not an  Affiliate  or as  otherwise  expressly  approved  in  writing by the
Required Banks.

     SECTION 5.20.  Compliance with ERISA.  Neither the Parent Guarantor nor the
Borrower shall directly or indirectly,  and neither the Parent Guarantor nor the
Borrower shall permit any member of the Controlled  Group directly or indirectly
(i) to  terminate,  any  Qualified  Plan subject to Title IV of ERISA,  so as to




                                       52

<PAGE>


result in any material (in the opinion of the Required  Banks)  liability to the
Borrower  or any  member of the  Controlled  Group,  (ii) to permit to exist any
ERISA  Event,  which  presents  the risk of a  material  (in the  opinion of the
Required  Banks)  liability of any member of the Controlled  Group,  or (iii) to
make a complete or partial withdrawal (within the meaning of ERISA Section 4201)
from any  Multiemployer  Plan so as to result in any material (in the opinion of
the  Required  Banks)  liability to any member of the  Controlled  Group or (iv)
permit the  present  value of all  nonforfeitable  accrued  benefits  under each
Qualified  Plan  (using  the  actuarial  assumptions  utilized  by the PBGC upon
termination  of a Qualified  Plan)  materially  (in the opinion of the  Required
Banks) to exceed the fair market  value of  Qualified  Plan assets  allocable to
such benefits, all determined as of the most recent valuation date for each such
Qualified Plan.

     SECTION 5.21. Restricted Payments. The Parent Guarantor will not declare or
make any dividend  payment or other  distribution of assets,  properties,  cash,
rights,  obligations  or securities on account of any shares of any class of its
capital stock or purchase,  redeem or otherwise acquire for value (or permit any
member of the Parent  Guarantor  Group to do so) any shares of its capital stock
or any  warrants,  rights or options to acquire  such  shares,  now or hereafter
outstanding.

     SECTION  5.22.  Accounting  Changes.  Neither the  Borrower  nor the Parent
Guarantor  will,  nor will permit any member of the Parent  Guarantor  Group to,
make any  significant  change in accounting  treatment and reporting  practices,
except as required by GAAP, or change the fiscal year of the Parent Guarantor or
any of its Subsidiaries.

     SECTION 5.23. Limitation on Indebtedness.  Neither the Parent Guarantor nor
the Borrower shall,  nor shall either permit any member of the Parent  Guarantor
Group (other than AMRC Holdings and  Subsidiaries  of AMRC Holdings) to, create,
incur, assume, guaranty, suffer to exist, or otherwise become or remain directly
or indirectly liable with respect to, any Indebtedness, except for:

     (a) accounts  payable to trade creditors for goods and services and current
operating liabilities (not the result of the borrowing of money) incurred in the
ordinary course of the Parent  Guarantor's,  the Borrower's or the  Subsidiary's
business, as the case may be, in accordance with customary terms and paid within
the specified time,  unless  contested in good faith by appropriate  proceedings
and reserved for in accordance with GAAP;

     (b) Indebtedness represented by Rate Contracts;



                                       53

<PAGE>



     (c) income taxes payable and deferred taxes;

     (d) accrued expenses and deferred income;

     (e)  Indebtedness  under the Senior Notes in an aggregate  principal amount
not  to  exceed  $335,000,000  and  Contingent  Obligations  of  the  Borrower's
Subsidiaries  and of the Parent  Guarantor in respect  thereof (such  Contingent
Obligations  of the Parent  Guarantor  to be  subordinated  as  described in the
Offering Memorandum);

     (f) Indebtedness under the Term Credit Agreement;

     (g) Contingent  Obligations incurred in connection with any lease financing
of mobile communications terminals, not exceeding $5,000,000 in the aggregate in
principal amount;

     (h)  Indebtedness  outstanding  on the  Effective  Date and  identified  on
Schedule 5.23;

     (i) Indebtedness  under the Financial  Management Account Line of Credit of
the Borrower  payable to the order of Wachovia Bank of North Carolina,  N.A., in
an aggregate principal amount at any time not exceeding $2,500,000;

     (j)  Indebtedness  incurred to finance  In-Orbit  Insurance in an aggregate
amount outstanding at any time not to exceed $6,000,000;

     (k) Vendor Financing Indebtedness in an aggregate amount outstanding at any
time not to exceed $10,000,000; and

     (l) any other Indebtedness incurred after the Effective Date; provided that
the aggregate outstanding principal amount of all such Indebtedness shall not at
any time exceed $15,000,000.



                                    ARTICLE 6
                                    DEFAULTS

     SECTION 6.01.  Events of Default.  If one or more of the  following  events
("Events of Default") shall have occurred and be continuing:

     (a) the  Borrower  shall fail to pay any  principal of any Loan when due or
any interest, any fees or any other amount payable hereunder within two Business


                                       54

<PAGE>



Days of the date when due, or one or more Shareholder Guarantors shall have made
more than two capital  contributions  or Investments in the Parent  Guarantor or
any Subsidiary thereof (or more than one during any twelve-month period) for the
principal  purpose of permitting  the Borrower to pay any  principal,  interest,
fees or other amounts payable hereunder;

     (b) the Borrower or the Parent  Guarantor  shall fail to observe or perform
any covenant contained in Article 5, other than those contained in Sections 5.01
through 5.05, 5.07 through 5.10, and 5.14;

     (c) the Borrower or the Parent  Guarantor  shall fail to observe or perform
any covenant or agreement  contained in this Agreement (other than those covered
by clause (a) or (b) above) for 20 days after  notice  thereof has been given to
the Borrower by the Administrative Agent at the request of any Bank;

     (d) any  representation,  warranty,  certification or statement made by the
Borrower, a Subsidiary of the Borrower or the Parent Guarantor in this Agreement
or any other Loan Document or in any certificate,  financial  statement or other
document delivered pursuant to this Agreement shall prove to have been incorrect
in any material respect when made (or deemed made);

     (e) the Parent  Guarantor or any Subsidiary of the Parent  Guarantor  shall
fail to make any payment in respect of (x) any obligation  under the Term Credit
Agreement  or (y) any other  Indebtedness  or  Contingent  Obligation  having an
aggregate  principal and face amount of more than $5,000,000,  in each case when
due (whether by scheduled maturity, required prepayment, acceleration, demand or
otherwise)  and such  failure  continues  after the  applicable  grace period or
notice period, if any, specified in the document relating thereto;

     (f) any event or condition shall occur which results in the acceleration of
the maturity of (x) any  Indebtedness  or Contingent  Obligation  under the Term
Credit Agreement or (y) any other  Indebtedness or Contingent  Obligation of the
Parent  Guarantor or any Subsidiary of the Parent  Guarantor having an aggregate
principal or face amount of more than $5,000,000 or enables (or, with the giving
of  notice  or lapse of time or  both,  would  enable)  the  holder  of any such
Indebtedness  or  Contingent  Obligation  or any Person  acting on such holder's
behalf to accelerate the maturity thereof;

     (g) the Parent  Guarantor  or any  Principal  Subsidiary  shall  commence a
voluntary case or other proceeding seeking liquidation,  reorganization or other
relief with respect to itself or its debts under any  bankruptcy,  insolvency or
other  similar law now or  hereafter in effect or seeking the  appointment  of a
trustee, receiver, liquidator,  custodian or other similar official of it or any




                                       55

<PAGE>


substantial part of its property,  or shall consent to any such relief or to the
appointment of or taking  possession by any such official in an involuntary case
or other proceeding commenced against it, or shall make a general assignment for
the  benefit  of  creditors,  or shall fail  generally  to pay its debts as they
become  due,  or  shall  take  any  corporate  action  to  authorize  any of the
foregoing;

     (h) an involuntary case or other proceeding shall be commenced  against the
Parent Guarantor or any Principal Subsidiary seeking liquidation, reorganization
or other relief with respect to it or its debts under any bankruptcy, insolvency
or other similar law now or hereafter in effect or seeking the  appointment of a
trustee, receiver, liquidator,  custodian or other similar official of it or any
substantial part of its property,  and such involuntary case or other proceeding
shall remain  undismissed  and unstayed for a period of 60 days; or an order for
relief shall be entered against the Parent Guarantor or any Principal Subsidiary
under the federal bankruptcy laws as now or hereafter in effect;

     (i) (1) any  member of the  Controlled  Group  shall  fail to pay when due,
after the expiration of any applicable  grace period,  any  installment  payment
with respect to its withdrawal  liability  under a  Multiemployer  Plan; (2) any
member  of  the  Controlled   Group  shall  fail  to  satisfy  its  contribution
requirements  under Section 412(c)(11) of the Code, whether or not it has sought
a waiver  under  Section  412(d) of the Code;  (3) in the case of an ERISA Event
involving the withdrawal from a Plan of a "substantial  employer" (as defined in
Section  4001(a)(2) or Section  4062(e) of ERISA),  the  withdrawing  employer's
proportionate  share of that Plan's  Unfunded  Pension  Liabilities is more than
$5,000,000  or 10% of its net  worth,  if  greater;  (4) in the case of an ERISA
Event involving the complete or partial  withdrawal  from a Multiemployer  Plan,
the  withdrawing  employer has  incurred a withdrawal  liability in an aggregate
amount exceeding $5,000,000 or 10% of its net worth, if greater; (5) in the case
of an ERISA  Event not  described  in clause (3) or (4),  the  Unfunded  Pension
Liabilities  of the relevant  Plan or Plans exceed  $5,000,000 or 10% of its net
worth,  if greater;  (6) a Plan that is intended to be qualified  under  Section
401(a) of the Code shall lose its qualification,  and the loss can reasonably be
expected  to  impose  on any  member  of the  Controlled  Group  liability  (for
additional taxes, to Plan participants, or otherwise) in the aggregate amount of
$5,000,000 or 10% of its net worth, if greater or more; (7) the  commencement or
increase of  contributions  to, the adoption of, or the  amendment of a Plan by,
any member of the  Controlled  Group shall  result in a net increase in unfunded
liabilities to the Borrower or an ERISA Affiliate in excess of $5,000,000 or 10%
of net worth,  if greater;  or (8) the  occurrence of any  combination of events
listed in clauses  (3)  through (7) that  involves a net  increase in  aggregate
Unfunded Pension Liabilities and unfunded liabilities in excess of $5,000,000 or
10% of its net worth, if greater;




                                       56

<PAGE>



     (j) one or more final judgments, orders or decrees shall be entered against
the Parent  Guarantor or any member of the Parent  Guarantor  Group involving in
the  aggregate a liability  (not fully  covered by insurance and as to which the
insurer has not acknowledged liability) more than an amount equal to the greater
of (i) $5,000,000 and (ii) 10% of the Parent Guarantor's net worth, and the same
shall remain unvacated, undischarged,  unstayed or unbonded pending appeal for a
period of 60 days after the entry thereof; or

     (k) any  non-monetary  judgment,  order or decree shall be rendered against
the Parent  Guarantor  or any of its  Subsidiaries  which  could  reasonably  be
expected to have a Material Adverse Effect,  and enforcement  proceedings  shall
have been commenced by any Person upon such judgment or order which shall remain
unstayed for any period of 10 consecutive days or more; or

     (l) the FCC or any other  Governmental  Authority  shall  revoke or fail to
renew any FCC License or any other material license,  permit or franchise of the
Parent Guarantor or any of its  Subsidiaries;  the Borrower shall for any reason
lose any FCC License or any other material license,  permit or franchise; or the
Borrower  shall  suffer  the  imposition  of  any  restraining  order,   escrow,
suspension or impound of funds in connection  with any  proceeding  (judicial or
administrative)  with respect to any FCC License or any other material  license,
permit or franchise;

     (m) there shall occur and be continuing a Material Adverse Effect;

     (n) the Borrower  shall breach or default  under any Rate Contract to which
any Bank is a party,  if the  effect of such  breach or  default is to allow the
Bank to proceed  against the  Borrower to satisfy any claim of the Bank  against
the Borrower in respect of such Rate Contract;

     (o) any  provision of Article 9 of this  Agreement  shall for any reason be
revoked or invalidated, or otherwise cease to be in full force and effect;

     (p) there shall occur a Change in Control;

     (q) any Shareholder  Guarantor (other than Baron Capital,  so long as, with
respect to any failure to make a payment  described  in clause  (ii)  below,  an
amount equal to such payment is paid under the Baron  Capital  Letter of Credit)
shall fail to make any payment (i) in respect of any  Indebtedness or Contingent
Obligation having an aggregate principal or face amount of more than $75,000,000
or (ii) under its Shareholder  Guaranty when due (whether by scheduled maturity,



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<PAGE>


required  prepayment,  acceleration,  demand  or  otherwise)  and  such  failure
continues after the applicable grace period or notice period, if any,  specified
in the document relating thereto;

     (r) any event or condition shall occur which results in the acceleration of
the maturity of any  Indebtedness  or Contingent  Obligation of any  Shareholder
Guarantor  (other than Baron  Capital)  having an  aggregate  principal  or face
amount of more than  $75,000,000 or enables the holder of such  Indebtedness  or
Contingent Obligation or any Person acting on such holder's behalf to accelerate
the maturity thereof;

     (s) any  Shareholder  Guaranty or the Baron Capital  Letter of Credit shall
for any reason be revoked or invalidated or otherwise  cease to be in full force
and effect (other than in accordance with its terms as the result of performance
in full of the relevant Shareholder  Guarantor's  obligations thereunder) or any
Shareholder  Guarantor  (other than Baron Capital) shall so assert in writing or
any  Shareholder  Guarantor  shall  bring an  action  to limit  its  liabilities
thereunder;

     (t) Hughes' senior  unsecured  long-term  securities  (without  third-party
credit  enhancement)  shall not be rated  Baa3 or above by  Moody's  and BBB- or
above by S&P; or

     (u) Hughes and either other  Shareholder  Guarantor shall have notified any
of the Agents and the banks of the  existence of a Guaranty  Issuance  Agreement
Event of Default;

then, and in every such event, the  Administrative  Agent shall (i) if requested
by Banks having more than 50% in aggregate amount of the Commitments,  by notice
to the Borrower  terminate the Commitments  and they shall thereupon  terminate,
and (ii) if requested by Banks holding more than 50% of the aggregate  principal
amount of the Loans, by notice to the Borrower  declare the Loans (together with
accrued  interest  thereon)  to  be,  and  the  Loans  shall  thereupon  become,
immediately due and payable without presentment, demand, protest or other notice
of any kind,  all of which are hereby waived by the  Borrower;  provided that in
the case of any of the  Events of Default  specified  in clause (g) or (h) above
with  respect to the  Borrower,  without any notice to the Borrower or any other
act by the  Administrative  Agent or the Banks, the Commitments  shall thereupon
terminate and the Loans  (together with accrued  interest  thereon) shall become
immediately due and payable without presentment, demand, protest or other notice
of any kind,  all of which are  hereby  waived by the  Borrower.  If any  amount
payable under this Agreement shall not be paid when due, then the Administrative
Agent  shall,  if  requested  by Banks  holding  more than 50% of the  aggregate
principal  amount  (excluding any Loans held by the Borrower or any  Shareholder




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<PAGE>


Guarantor or any Affiliate of the  foregoing) of the Tranche A Loans,  Tranche B
Loans or Tranche C Loans,  as the case may be, demand payment  thereof under the
relevant Shareholder Guaranty.

     SECTION 6.02. Notice of Default. The Administrative Agent shall give notice
to the Borrower under Section 6.01(c)  promptly upon being requested to do so by
any Bank and shall thereupon notify all the Banks thereof.



                                    ARTICLE 7
                                   THE AGENTS

     SECTION 7.01. Appointment and Authorization. Each Bank irrevocably appoints
and  authorizes  each  Agent to take such  action as agent on its  behalf and to
exercise  such  powers  under  this  Agreement,  the Notes and each  other  Loan
Document as are delegated to such Agent by the terms hereof or thereof, together
with all such powers as are reasonably incidental thereto.

     SECTION 7.02.  Agents and Affiliates.  Morgan Guaranty Trust Company of New
York shall have the same  rights and powers  under this  Agreement  as any other
Bank and may exercise or refrain from  exercising the same as though it were not
an Agent, and each of Toronto Dominion  (Texas),  Inc. and Morgan Guaranty Trust
Company of New York and its affiliates may accept  deposits from, lend money to,
and generally  engage in any kind of business  with the Parent  Guarantor or any
Subsidiary or affiliate of the Parent Guarantor as if it were not an Agent.

     SECTION 7.03. Action by Agents. The obligations of the Agents hereunder are
only those  expressly set forth herein.  Without  limiting the generality of the
foregoing,  the Agents  shall not be required to take any action with respect to
any Default, except as expressly provided in Article 6.

     SECTION  7.04.  Consultation  with  Experts.  Either Agent may consult with
legal  counsel  (who may be counsel for the  Borrower or the Parent  Guarantor),
independent public accountants and other experts selected by it and shall not be
liable  for any  action  taken or  omitted  to be  taken by it in good  faith in
accordance with the advice of such counsel, accountants or experts.

     SECTION 7.05. Liability of Agents. No Agent or any of its affiliates or any
of their respective directors, officers, agents or employees shall be liable for
any action taken or not taken by it in connection  herewith (i) with the consent
or at the request of the Required  Banks or (ii) in the absence of its own gross
negligence or willful  misconduct.  No Agent or any of its  affiliates or any of
their respective directors,  officers,  agents or employees shall be responsible



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<PAGE>


for or have any duty to  ascertain,  inquire  into or verify (i) any  statement,
warranty  or  representation  made in  connection  with  this  Agreement  or any
borrowing hereunder;  (ii) the performance or observance of any of the covenants
or agreements of the Borrower or the Parent Guarantor; (iii) the satisfaction of
any  condition  specified in Article 3, except  receipt of items  required to be
delivered to the  Documentation  Agent; or (iv) the validity,  effectiveness  or
genuineness  of this  Agreement,  the Notes or any other  instrument  or writing
furnished in connection  herewith.  No Agent shall incur any liability by acting
in reliance upon any notice, consent,  certificate,  statement, or other writing
(which may be a bank wire,  telex,  facsimile  transmission or similar  writing)
believed by it to be genuine or to be signed by the proper party or parties.

     SECTION 7.06. Indemnification.  Each Bank shall, ratably in accordance with
its  Commitment,  indemnify  each Agent,  its  affiliates  and their  respective
directors,  officers,  agents and employees (to the extent not reimbursed by the
Borrower or the Parent Guarantor)  against any cost,  expense (including counsel
fees and disbursements),  claim, demand,  action, loss or liability (except such
as result from such  indemnitee's  gross negligence or willful  misconduct) that
such  indemnitee  may suffer or incur in connection  with this  Agreement or any
action taken or omitted by such indemnitee hereunder.

     SECTION  7.07.  Credit  Decision.  Each  Bank  acknowledges  that  it  has,
independently  and without  reliance  upon either  Agent or any other Bank,  and
based on such documents and information as it has deemed  appropriate,  made its
own credit  analysis and decision to enter into this  Agreement.  Each Bank also
acknowledges that it will,  independently and without reliance upon either Agent
or any other Bank, and based on such documents and  information as it shall deem
appropriate at the time,  continue to make its own credit decisions in taking or
not taking any action under this Agreement.

     SECTION  7.08.  Successor  Agent.  Either  Agent may  resign at any time by
giving notice thereof to the Banks and the Borrower.  Upon any such resignation,
the  Required  Banks  shall have the right to appoint a successor  Agent.  If no
successor  Agent shall have been so appointed by the Required  Banks,  and shall
have accepted such  appointment,  within 30 days after the retiring  Agent gives
notice of  resignation,  then the  retiring  Agent may,  on behalf of the Banks,
appoint a  successor  Agent,  which  shall be a  commercial  bank  organized  or
licensed  under the laws of the United States of America or of any State thereof
and having a combined  capital  and  surplus of at least  $50,000,000.  Upon the
acceptance of its  appointment  as Agent  hereunder by a successor  Agent,  such
successor Agent shall thereupon succeed to and become vested with all the rights
and duties of the retiring  Agent,  and the retiring  Agent shall be  discharged
from  its  duties  and  obligations   hereunder.   After  any  retiring  Agent's



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<PAGE>


resignation  hereunder as Agent,  the  provisions of this Article shall inure to
its  benefit as to any  actions  taken or omitted to be taken by it while it was
Agent.

     SECTION 7.09.  Agents' Fees.  The Borrower  shall pay to each Agent for its
own account fees in the amounts and at the times previously  agreed upon between
the Borrower and such Agent.



                                    ARTICLE 8
                             CHANGE IN CIRCUMSTANCES

     SECTION 8.01. Basis for Determining  Interest Rate Inadequate or Unfair. If
on or prior to the first day of any Interest Period for any Euro-Dollar Loan:

     (a) the  Administrative  Agent  is  advised  by the  Reference  Banks  that
deposits in dollars (in the  applicable  amounts)  are not being  offered to the
Reference Banks in the London interbank market for such Interest Period, or

     (b)  Banks  having  50% or more of the  aggregate  principal  amount of the
affected  Loans  advise  the  Administrative  Agent  that  the  Adjusted  London
Interbank  Offered  Rate as  determined  by the  Administrative  Agent  will not
adequately  and  fairly  reflect  the  cost  to  such  Banks  of  funding  their
Euro-Dollar  Loans for such  Interest  Period,  the  Administrative  Agent shall
forthwith give notice thereof to the Borrower and the Banks, whereupon until the
Administrative Agent notifies the Borrower that the circumstances giving rise to
such  suspension  no  longer  exist,  (i) the  obligations  of the Banks to make
Euro-Dollar  Loans  or to  continue  or  convert  outstanding  Loans  as or into
Euro-Dollar Loans shall be suspended and (ii) each outstanding  Euro-Dollar Loan
shall be  converted  into a Base Rate  Loan on the last day of the then  current
Interest  Period   applicable   thereto.   Unless  the  Borrower   notifies  the
Administrative  Agent at least two Domestic Business Days before the date of any
Euro-Dollar  Borrowing for which a Notice of Borrowing has previously been given
that it elects not to borrow on such date,  such Borrowing shall instead be made
as a Base Rate Borrowing.  The Administrative Agent shall notify the Borrower as
soon as reasonably possible upon learning that the circumstances  giving rise to
such suspension no longer exist.

     SECTION 8.02. Illegality.  If, on or after the date of this Agreement,  the
adoption  of any  applicable  law,  rule or  regulation,  or any  change  in any
applicable  law,  rule or  regulation,  or any change in the  interpretation  or
administration thereof by any governmental authority, central bank or comparable




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<PAGE>


agency charged with the interpretation or administration  thereof, or compliance
by any Bank (or its  Euro-Dollar  Lending  Office) with any request or directive
(whether or not having the force of law) of any such authority,  central bank or
comparable  agency  shall make it  unlawful or  impossible  for any Bank (or its
Euro-Dollar  Lending Office) to make, maintain or fund its Euro-Dollar Loans and
such Bank shall so notify the  Administrative  Agent, the  Administrative  Agent
shall  forthwith  give  notice  thereof  to the other  Banks  and the  Borrower,
whereupon  until such Bank  notifies the Borrower and the  Administrative  Agent
that the  circumstances  giving rise to such  suspension  no longer  exist,  the
obligation of such Bank to make  Euro-Dollar  Loans,  or to convert  outstanding
Loans into Euro-Dollar  Loans,  shall be suspended.  Before giving any notice to
the Administrative  Agent pursuant to this Section,  such Bank shall designate a
different Euro-Dollar Lending Office if such designation will avoid the need for
giving  such notice and will not, in the  judgment  of such Bank,  be  otherwise
disadvantageous  to such Bank. If such notice is given, each Euro-Dollar Loan of
such Bank then outstanding  shall be converted to a Base Rate Loan either (a) on
the last day of the then current Interest Period  applicable to such Euro-Dollar
Loan if such Bank may  lawfully  continue to maintain and fund such Loan to such
day or (b)  immediately  if such Bank shall  determine  that it may not lawfully
continue to maintain and fund such Loan to such day.  Each Bank shall notify the
Administrative  Agent and the Borrower as soon as reasonably  possible after the
circumstances  giving  rise to any  suspension  by such Bank  described  in this
Section 8.02 no longer exist.

     SECTION 8.03.  Increased  Cost and Reduced  Return.  (a) If on or after the
date hereof,  the adoption of any  applicable  law, rule or  regulation,  or any
change  in  any  applicable  law,  rule  or  regulation,  or any  change  in the
interpretation or administration thereof by any governmental authority,  central
bank or comparable  agency  charged with the  interpretation  or  administration
thereof,  or compliance by any Bank (or its Applicable  Lending Office) with any
request  or  directive  (whether  or not  having  the  force of law) of any such
authority,  central  bank or  comparable  agency  shall  impose,  modify or deem
applicable any reserve  (including,  without  limitation,  any such  requirement
imposed by the Board of Governors of the Federal Reserve  System,  but excluding
any such requirement included in an applicable  Euro-Dollar Reserve Percentage),
special deposit,  insurance assessment or similar requirement against assets of,
deposits  with or for the  account of, or credit  extended  by, any Bank (or its
Applicable  Lending  Office)  or shall  impose  on any  Bank (or its  Applicable
Lending Office) or the London interbank market any other condition affecting its
Euro-Dollar  Loans, its Note or its obligation to make Euro-Dollar Loans and the
result  of any of the  foregoing  is to  increase  the cost to such Bank (or its
Applicable  Lending Office) of making or maintaining any Euro-Dollar Loan, or to
reduce  the  amount  of any sum  received  or  receivable  by such  Bank (or its
Applicable  Lending  Office) under this Agreement or under its Note with respect



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<PAGE>


thereto,  by an amount deemed by such Bank to be material,  then, within 15 days
after  demand  by  such  Bank  (with a copy to the  Administrative  Agent),  the
Borrower  shall pay to such  Bank such  additional  amount  or  amounts  as will
compensate  such Bank for such increased cost or reduction;  provided,  however,
that in the case of an increase  referred to above  resulting from the published
interpretation by a governmental authority,  such Bank shall be entitled to make
demand  on  the  Borrower  in  respect  thereof  only  within  180  days  of the
publication of such interpretation.

     (b) If any Bank shall have  determined  that,  after the date  hereof,  the
adoption of any applicable law, rule or regulation  regarding  capital adequacy,
or any  change  in any  such  law,  rule or  regulation,  or any  change  in the
interpretation or administration thereof by any governmental authority,  central
bank or comparable  agency  charged with the  interpretation  or  administration
thereof,  or any request or directive regarding capital adequacy (whether or not
having  the  force of law) of any such  authority,  central  bank or  comparable
agency,  has or would have the effect of reducing  the rate of return on capital
of such  Bank  (or its  Parent)  as a  consequence  of such  Bank's  obligations
hereunder  to a level  below  that which  such Bank (or its  Parent)  could have
achieved  but for such  adoption,  change,  request or  directive  (taking  into
consideration its policies with respect to capital adequacy) by an amount deemed
by such Bank to be material, then from time to time, within 15 days after demand
by such Bank (with a copy to the  Administrative  Agent), the Borrower shall pay
to such Bank such additional  amount or amounts as will compensate such Bank (or
its  Parent)  for  such  reduction;  provided,  however,  that in the case of an
increase  referred to above  resulting  from the published  interpretation  by a
governmental  authority,  such  Bank  shall be  entitled  to make  demand on the
Borrower  in respect  thereof  only within 180 days of the  publication  of such
interpretation.

     (c) Each Bank will  promptly  notify the  Borrower  and the  Administrative
Agent of any event of which it has knowledge,  occurring  after the date hereof,
which will entitle such Bank to  compensation  pursuant to this Section and will
designate a different  Lending  Office if such  designation  will avoid the need
for, or reduce the amount of, such compensation and will not, in the judgment of
such Bank, be otherwise  disadvantageous to such Bank. A certificate of any Bank
claiming compensation under this Section and setting forth the additional amount
or amounts to be paid to it  hereunder  shall be  conclusive  in the  absence of
manifest  error.  In determining  such amount,  such Bank may use any reasonable
averaging  and  attribution  methods.  Each Bank will notify the  Administrative
Agent and the Borrower as soon as  reasonably  possible  after any  circumstance
entitling such Bank to  compensation  pursuant to this Section 8.03(c) no longer
exists.



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<PAGE>



     SECTION  8.04.  Taxes.  (a) For the  purposes  of this  Section  8.04 , the
following terms have the following meanings:

     "Taxes" means any and all present or future taxes, duties, levies, imposts,
deductions,  charges or withholdings with respect to any payment by the Borrower
or the Parent Guarantor, as the case may be, pursuant to this Agreement or under
any Note, and all liabilities with respect thereto, excluding (i) in the case of
each Bank and Agent, taxes imposed on its income, and franchise or similar taxes
imposed on it, by a jurisdiction  under the laws of which such Bank or Agent (as
the case may be) is  organized  or in which its  principal  executive  office is
located or, in the case of each Bank, in which its Applicable  Lending Office is
located and (ii) in the case of each Bank,  any United  States  withholding  tax
imposed on such  payments  but only to the  extent  that such Bank is subject to
United  States  withholding  tax at the time such Bank first  becomes a party to
this Agreement.

     "Other  Taxes" means any present or future stamp or  documentary  taxes and
any other excise or property taxes,  or similar  charges or levies,  which arise
from any payment made  pursuant to this  Agreement or under any Note or from the
execution or delivery of, or  otherwise  with respect to, this  Agreement or any
Note.

     (b) Any and all payments by the Borrower or the Parent  Guarantor to or for
the  account  of any Bank or Agent  hereunder  or under  any Note  shall be made
without  deduction for any Taxes or Other Taxes;  provided that, if the Borrower
or the Parent  Guarantor  shall be  required by law to deduct any Taxes or Other
Taxes  from  any such  payments,  (i) the sum  payable  shall  be  increased  as
necessary  so that after making all required  deductions  (including  deductions
applicable to additional sums payable under this Section) such Bank or Agent (as
the case may be) receives an amount equal to the sum it would have  received had
no such deductions been made, (ii) the Borrower or the Parent Guarantor,  as the
case may be, shall make such  deductions,  (iii) the Borrower shall pay the full
amount  deducted  to the  relevant  taxation  authority  or other  authority  in
accordance with applicable law and (iv) the Borrower or the Parent Guarantor, as
the case may be,  shall  furnish to the  Administrative  Agent,  at its  address
referred to in Section  10.01 , the  original  or a certified  copy of a receipt
evidencing payment thereof.

     (c) The  Borrower  agrees  to  indemnify  each  Bank and Agent for the full
amount of Taxes or Other  Taxes  (including,  without  limitation,  any Taxes or
Other Taxes  imposed or asserted by any  jurisdiction  on amounts  payable under
this  Section) paid by such Bank or Agent (as the case may be) and any liability
(including penalties, interest and expenses, other than those resulting from any
act or failure to act by such Bank) arising  therefrom or with respect  thereto.




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This  indemnification  shall be paid within 15 days after such Bank or Agent (as
the case may be) makes demand therefor.

     (d) Each Bank organized under the laws of a jurisdiction outside the United
States,  on or prior to the date of its execution and delivery of this Agreement
in the case of each Bank listed on the signature pages hereof and on or prior to
the date on which it  becomes a Bank in the case of each  other  Bank,  and from
time to time  thereafter  if requested  in writing by the Borrower  (but only so
long as such Bank remains  lawfully  able to do so),  shall provide the Borrower
and the Administrative Agent with Internal Revenue Service form 1001 or 4224, as
appropriate,  or any successor form prescribed by the Internal  Revenue Service,
certifying  that such Bank is entitled to benefits under an income tax treaty to
which the United  States is a party which  exempts  the Bank from United  States
withholding  tax or reduces the rate of withholding  tax on payments of interest
for the account of such Bank or certifying that the income  receivable  pursuant
to this  Agreement  is  effectively  connected  with the  conduct  of a trade or
business in the United States.

     (e) For any period  with  respect to which a Bank has failed to provide the
Borrower  or the  Administrative  Agent with the  appropriate  form  pursuant to
Section  8.04(d)  (unless  such  failure  is due to a change in  treaty,  law or
regulation  occurring  subsequent to the date on which such form  originally was
required to be  provided),  such Bank shall not be  entitled to  indemnification
under  Section  8.04(b) or 8.04(c) with  respect to Taxes  imposed by the United
States;  provided that if a Bank, which is otherwise exempt from or subject to a
reduced rate of withholding tax, becomes subject to Taxes because of its failure
to deliver a form required hereunder, the Borrower shall take such steps as such
Bank shall reasonably request to assist such Bank to recover such Taxes.

     (f) If the Borrower or the Parent  Guarantor is required to pay  additional
amounts to or for the account of any Bank  pursuant to this  Section,  then such
Bank will change the  jurisdiction  of its Applicable  Lending Office if, in the
judgment  of such  Bank,  such  change  (i) will  eliminate  or reduce  any such
additional  payment  which  may  thereafter  accrue  and  (ii) is not  otherwise
disadvantageous to such Bank.

     SECTION 8.05. Base Rate Loans Substituted for Affected  Euro-Dollar  Loans.
If (i) the  obligation  of any Bank to make,  or convert  outstanding  Loans to,
Euro-Dollar  Loans has been suspended  pursuant to Section 8.02 or (ii) any Bank
has  demanded  compensation  under  Section  8.03 or 8.04  with  respect  to its
Euro-Dollar Loans and the Borrower shall, by at least five Euro-Dollar  Business
Days' prior notice to such Bank through the  Administrative  Agent, have elected
that the provisions of this Section shall apply to such Bank,  then,  unless and



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until such Bank notifies the Borrower that the circumstances giving rise to such
suspension or demand for compensation no longer exist:

     (a) all Loans which would  otherwise be made by such Bank as (or  continued
as or converted  into)  Euro-Dollar  Loans shall  instead be Base Rate Loans (on
which interest and principal shall be payable contemporaneously with the related
Euro-Dollar Loans of the other Banks); and

     (b) after each of its Euro-Dollar  Loans has been repaid (or converted to a
Base Rate Loan),  all payments of principal  which would otherwise be applied to
repay  such  Euro-Dollar  Loans  shall be  applied  to repay its Base Rate Loans
instead.

If such Bank  notifies the Borrower that the  circumstances  giving rise to such
notice no longer apply,  the principal  amount of each such Base Rate Loan shall
be converted  into a  Euro-Dollar  Loan on the first day of the next  succeeding
Interest Period applicable to the related Euro-Dollar Loans of the other Banks.



                                    ARTICLE 9
                                 PARENT GUARANTY

     SECTION  9.01.   The  Parent   Guaranty.   The  Parent   Guarantor   hereby
unconditionally  guarantees  the full and  punctual  payment  (whether at stated
maturity,  upon  acceleration  or otherwise) of the principal of and interest on
each Note issued by the Borrower  pursuant to this  Agreement,  and the full and
punctual  payment  of all other  amounts  payable  by the  Borrower  under  this
Agreement.  Upon failure by the Borrower to pay punctually any such amount,  the
Parent  Guarantor  shall  forthwith  on demand pay the amount not so paid at the
place and in the manner specified in this Agreement.

     SECTION  9.02.  Guaranty  Unconditional.  The  obligations  of  the  Parent
Guarantor  hereunder shall be  unconditional  and absolute and, without limiting
the generality of the foregoing, shall not be released,  discharged or otherwise
affected by:

     (a) any extension,  renewal, settlement,  compromise,  waiver or release in
respect of any  obligation of the Borrower  under this Agreement or any Note, by
operation of law or otherwise;

     (b) any modification or amendment of or supplement to this Agreement or any
Note;


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<PAGE>




     (c) any release, impairment,  non-perfection or invalidity of any direct or
indirect security for any obligation of the Borrower under this Agreement or any
Note;

     (d) any change in the  corporate  existence,  structure or ownership of the
Borrower,  or  any  insolvency,  bankruptcy,  reorganization  or  other  similar
proceeding  affecting  the  Borrower or its assets or any  resulting  release or
discharge of any  obligation of the Borrower  contained in this Agreement or any
Note;

     (e) the  existence  of any claim,  set-off or other rights which the Parent
Guarantor may have at any time against the Borrower,  either Agent,  any Bank or
any other Person, whether in connection herewith or any unrelated  transactions,
provided  that nothing  herein shall  prevent the assertion of any such claim by
separate suit or compulsory counterclaim;

     (f) any invalidity or unenforceability  relating to or against the Borrower
for any reason of this Agreement or any Note, or any provision of applicable law
or  regulation  purporting  to  prohibit  the  payment  by the  Borrower  of the
principal of or interest on any Note or any other amount payable by the Borrower
under this Agreement; or

     (g) any other act or omission to act or delay of any kind by the  Borrower,
either Agent, any Bank or any other Person or any other circumstance  whatsoever
which might,  but for the  provisions of this  paragraph,  constitute a legal or
equitable discharge of the Parent Guarantor's obligations hereunder.

     SECTION 9.03.  Discharge Only Upon Payment in Full;  Restatement in Certain
Circumstances. The Parent Guarantor's obligations hereunder shall remain in full
force and effect until the  Commitments  shall have terminated and the principal
of and interest on the Notes and all other amounts payable by the Borrower under
this  Agreement  shall have been paid in full. If at any time any payment of the
principal of or interest on any Note or any other amount payable by the Borrower
under this Agreement is rescinded or must be otherwise restored or returned upon
the insolvency,  bankruptcy or reorganization of the Borrower or otherwise,  the
Parent Guarantor's  obligations  hereunder with respect to such payment shall be
reinstated at such time as though such payment had been due but not made at such
time.

     SECTION  9.04.  Waiver  by  the  Parent  Guarantor.  The  Parent  Guarantor
irrevocably  waives  acceptance  hereof,  presentment,  demand,  protest and any



                                       67

<PAGE>


notice not provided for herein,  as well as any requirement that at any time any
action be taken by any Person against the Borrower or any other Person.

     SECTION 9.05. Subrogation. Until such time as all principal of and interest
on each Note issued by the  Borrower  pursuant to this  Agreement  and all other
amounts payable by the Borrower under this Agreement have indefeasibly been paid
in full,  the  Parent  Guarantor  shall not assert any rights to which it may be
entitled, by operation of law or otherwise, upon making any payment hereunder to
be  subrogated  to the rights of the payee  against the Borrower with respect to
such payment or against any direct or indirect security  therefor,  or otherwise
to be  reimbursed,  indemnified  or  exonerated  by or for  the  account  of the
Borrower in respect thereof.

     SECTION 9.06. Stay of Acceleration. If acceleration of the time for payment
of any amount payable by the Borrower under this Agreement or any Note is stayed
upon insolvency,  bankruptcy or reorganization of the Borrower, all such amounts
otherwise  subject  to  acceleration  under  the terms of this  Agreement  shall
nonetheless be payable by the Parent Guarantor  hereunder forthwith on demand by
the Administrative  Agent made at the request of the requisite proportion of the
Banks specified in Article 6 of the Agreement.

     SECTION 9.07.  Subordination.  (a) The obligations of the Parent  Guarantor
under  this  Article 9 will be  subordinated  in right of  payment  to the prior
payment in full of all Senior Indebtedness.

     (b) Upon  any  distribution  to  creditors  of the  Parent  Guarantor  in a
liquidation  or  dissolution  of  the  Parent  Guarantor  or  in  a  bankruptcy,
reorganization,  insolvency,  receivership or similar proceeding relating to the
Parent Guarantor or its property,  an assignment for the benefit of creditors or
any marshalling of the Parent Guarantor's assets and liabilities, the holders of
Senior  Indebtedness  will  be  entitled  to  receive  payment  in  full  of all
Obligations with respect to Senior  Indebtedness  (including  interest after the
commencement  of any such  proceeding  at the rate  specified in the Term Credit
Agreement or otherwise  applicable thereto) before the Banks will be entitled to
receive any payment under this Article 9, and until all Obligations with respect
to Senior  Indebtedness  are paid in full, any  distribution  to which the Banks
would be entitled  shall be made to the holders of Senior  Indebtedness  (except
that the Banks may receive and retain Permitted Junior Securities).

     (c) The Parent Guarantor may not make any payment upon or in respect of its
obligations under this Article 9 (except in Permitted Junior  Securities) if (i)
a default in the payment of the  principal of,  premium,  if any, or interest on
Designated  Senior  Indebtedness  occurs and is continuing beyond any applicable


                                       68

<PAGE>



period of grace or (ii) any other  default  occurs  with  respect to  Designated
Senior  Indebtedness that permits holders of the Designated Senior  Indebtedness
as  to  which  such  default   relates  to  accelerate   its  maturity  and  the
Administrative  Agent  receives  notice of such  default  (a  "Payment  Blockage
Notice")  from the Parent  Guarantor  or the  holders of any  Designated  Senior
Indebtedness.  Payments under this Article 9 may and shall be resumed (i) in the
case of a  payment  default,  upon the date on which  such  default  is cured or
waived and (ii) in the case of a nonpayment default,  the earlier of the date on
which such  nonpayment  default is cured or waived or 179 days after the date on
which the applicable Payment Blockage Notice is received, unless the maturity of
any  Designated  Senior  Indebtedness  has been  accelerated.  No new  period of
payment  blockage  may be  commenced  unless and until (i) 360 days have elapsed
since the  effectiveness  of the immediately  prior Payment  Blockage Notice and
(ii) all scheduled payments of principal,  premium,  if any, and interest on the
Notes that have come due have been paid in full with cash. No nonpayment default
that existed or was  continuing on the date of delivery of any Payment  Blockage
Notice  to the  Administrative  Agent  shall  be,  or be made,  the  basis for a
subsequent Payment Blockage Notice.

     (d)  The  Parent   Guarantor   shall  promptly  notify  holders  of  Senior
Indebtedness  if  payment  of the Loans is  accelerated  because  of an Event of
Default.

     (e) As used in this Section 9.07, the following  capitalized terms have the
meanings set forth below:

     "Capital  Stock" means (i) in the case of a corporation,  corporate  stock,
(ii) in the case of an  association  or  business  entity,  any and all  shares,
interests,  participations,  rights or other equivalents (however designated) of
corporate  stock,  (iii)  in the  case of a  partnership  or  limited  liability
company,  partnership or membership  interests  (whether general or limited) and
(iv) any other interest or  participation  that confers on a Person the right to
receive a share of the profits and losses of, or distributions of assets of, the
issuing Person.

     "Designated  Senior  Indebtedness"  means (i) any Indebtedness  outstanding
under the Loan  Documents (as defined in the Term Credit  Agreement) or (ii) any
other Senior  Indebtedness  the principal amount of which is $25,000,000 or more
and  that  has  been  designated  by the  Parent  Guarantor  in  writing  to the
Administrative Agent as "Designated Senior Indebtedness".

     "Equity  Interests" means Capital Stock and all warrants,  options or other
rights to  acquire  Capital  Stock  (but  excluding  any debt  security  that is
convertible into, or exchangeable for, Capital Stock).


                                       69

<PAGE>



     "Permitted  Junior   Securities"  means  Equity  Interests  in  the  Parent
Guarantor or debt  securities that are  subordinated to all Senior  Indebtedness
(and  any debt  securities  issued  in  exchange  for  Senior  Indebtedness)  to
substantially  the same extent as, or to a greater extent than, the  obligations
of  the  Parent  Guarantor  under  this  Article  9 are  subordinated  to  Senor
Indebtedness.

     "Senior  Indebtedness"  means  Obligations in respect of the Loan Documents
(as  defined in the Term Credit  Agreement)  and any other  Indebtedness  of the
Parent Guarantor now or hereafter incurred except such Indebtedness specifically
designated  by the Parent  Guarantor in writing to the  Administrative  Agent as
subordinated  indebtedness  at  the  time  of  its  incurrence.  Notwithstanding
anything to the contrary in the foregoing,  Senior Indebtedness will not include
(i) any liability for federal,  state, local or other taxes owed or owing by the
Parent  Guarantor,  (ii) any  Indebtedness of the Parent Guarantor to any of its
Subsidiaries  or  other  Affiliates,  (iii)  any  trade  payables  or  (iv)  any
Indebtedness that is incurred in violation of this Agreement.



                                   ARTICLE 10
                                  MISCELLANEOUS

     SECTION 10.01.  Notices. All notices,  requests and other communications to
any  party  hereunder  shall  be in  writing  (including  bank  wire,  facsimile
transmission  or similar  writing) and shall be given to such party:  (a) in the
case of the Borrower,  the Parent  Guarantor or either Agent,  at its address or
facsimile number set forth on the signature pages hereof, (b) in the case of any
Bank,  at its  address  or  facsimile  number  set  forth in its  Administrative
Questionnaire  or (c) in the case of any party,  such other address or facsimile
number as such  party may  hereafter  specify  for the  purpose by notice to the
Agents and the Borrower.  Each such notice, request or other communication shall
be effective (i) if given by facsimile  transmission,  when  transmitted  to the
facsimile  number  specified  in this  Section  and  confirmation  of receipt is
received,  (ii) if given by mail, 72 hours after such communication is deposited
in the mails with first class postage  prepaid,  addressed as aforesaid or (iii)
if given by any other means,  when  delivered  at the address  specified in this
Section;  provided that notices to the  Administrative  Agent under Article 2 or
Article 8 shall not be effective until received.

     SECTION 10.02. No Waivers.  No failure or delay by either Agent or any Bank
in exercising  any right,  power or privilege  hereunder or under any Note shall
operate as a waiver  thereof  nor shall any single or partial  exercise  thereof
preclude  any other or further  exercise  thereof or the  exercise  of any other



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<PAGE>


right,  power or privilege.  The rights and remedies  herein  provided  shall be
cumulative and not exclusive of any rights or remedies provided by law.

     SECTION 10.03.  Expenses;  Indemnification.  (a) The Borrower shall pay (i)
all  out-of-pocket  expenses  of  the  Agents,  including  reasonable  fees  and
disbursements  of  special  counsel  for the  Agents,  in  connection  with  the
preparation  and  administration  of  this  Agreement,  any  waiver  or  consent
hereunder or any amendment  hereof or any Default or alleged  Default  hereunder
and (ii) if an Event of Default occurs,  all out-of-pocket  expenses incurred by
each Agent and Bank, including (without  duplication) the fees and disbursements
of outside counsel and the allocated cost of inside counsel,  in connection with
such  Event  of  Default  and  collection,   bankruptcy,  insolvency  and  other
enforcement proceedings resulting therefrom.

     (b) The Borrower agrees to indemnify each Agent and Bank,  their respective
affiliates and the respective directors,  officers,  agents and employees of the
foregoing  (each an  "Indemnitee")  and hold each  Indemnitee  harmless from and
against any and all  liabilities,  losses,  damages,  costs and  expenses of any
kind,  including,  without limitation,  the reasonable fees and disbursements of
counsel,  which  may be  incurred  by such  Indemnitee  in  connection  with any
investigative,  administrative  or  judicial  proceeding  (whether  or not  such
Indemnitee shall be designated a party thereto)  brought or threatened  relating
to or arising out of this Agreement or any actual or proposed use of proceeds of
Loans  hereunder;  provided  that no  Indemnitee  shall  have  the  right  to be
indemnified  hereunder  for such  Indemnitee's  own gross  negligence or willful
misconduct as determined by a court of competent jurisdiction.

     SECTION 10.04.  Sharing of Set-offs.  Each Bank agrees that if it shall, by
exercising  any right of set-off or  counterclaim  or otherwise  (other than any
such right against a Shareholder Guarantor),  receive payment of a proportion of
the aggregate amount of principal and interest due with respect to any Note held
by it which is greater than the proportion received by any other Bank in respect
of the  aggregate  amount of principal and interest due with respect to any Note
held by such other Bank, the Bank receiving such proportionately greater payment
shall  purchase such  participations  in the Notes held by the other Banks,  and
such  other  adjustments  shall be  made,  as may be  required  so that all such
payments of principal  and interest  with respect to the Notes held by the Banks
shall be shared by the Banks pro rata;  provided  that  nothing in this  Section
shall  impair  the  right of any  Bank to  exercise  any  right  of  set-off  or
counterclaim it may have and to apply the amount subject to such exercise to the
payment of indebtedness  of the Borrower or the Parent  Guarantor other than its
indebtedness hereunder. Each of the Borrower and the Parent Guarantor agrees, to
the fullest  extent it may  effectively  do so under  applicable  law,  that any



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<PAGE>


holder of a  participation  in a Note,  whether or not acquired  pursuant to the
foregoing arrangements, may exercise rights of set-off or counterclaim and other
rights  with  respect  to such  participation  as fully as if such  holder  of a
participation  were a direct creditor of the Borrower or the Parent Guarantor in
the amount of such participation.

     SECTION 10.05.  Amendments and Waivers.  Any provision of this Agreement or
the Notes may be amended or waived if, but only if, such  amendment or waiver is
in writing and is signed by the  Borrower and the  Required  Banks (and,  if the
rights or duties of an Agent are affected thereby, by such Agent); provided that
no such amendment or waiver shall,  unless signed by all the Banks, (a) increase
or decrease the  Commitment  of any Bank  (except for a ratable  decrease in the
Commitments of all Banks) or subject any Bank to any additional obligation,  (b)
reduce the principal of or rate of interest on any Loan, or any fees  hereunder,
(c)  postpone  the date fixed for any payment of principal of or interest on any
Loan, or any fees hereunder or for any scheduled reduction or termination of any
Commitment,  (d) release the Parent Guarantor from its obligations  hereunder or
the  Shareholder  Guarantors  from  their  obligations  under  the  Shareholders
Guaranties,  or (e) change the percentage of the Commitments or of the aggregate
unpaid  principal  amount of the Notes,  or the number of Banks,  which shall be
required  for the Banks or any of them to take any action  under this Section or
any other provision of this Agreement.

     SECTION 10.06. Successors and Assigns. (a) The provisions of this Agreement
shall be binding  upon and inure to the benefit of the parties  hereto and their
respective  successors  and assigns,  except that the Borrower may not assign or
otherwise  transfer  any of its rights  under this  Agreement  without the prior
written consent of all Banks.

     (b)  Any  Bank  may at  any  time  grant  to one or  more  banks  or  other
institutions (each a "Participant") participating interests in its Commitment or
any or all of  its  Loans.  In the  event  of  any  such  grant  by a Bank  of a
participating  interest  to a  Participant,  whether  or not upon  notice to the
Borrower and the Agents,  such Bank shall remain responsible for the performance
of its obligations hereunder,  and the Borrower and the Agents shall continue to
deal solely and directly  with such Bank in  connection  with such Bank's rights
and obligations under this Agreement.  Any agreement  pursuant to which any Bank
may grant  such a  participating  interest  shall  provide  that such Bank shall
retain  the sole right and  responsibility  to enforce  the  obligations  of the
Borrower  hereunder  including,  without  limitation,  the right to approve  any
amendment,  modification or waiver of any provision of this Agreement;  provided
that such  participation  agreement may provide that such Bank will not agree to
any modification, amendment or waiver of this Agreement described in clause (a),
(b),  (c), (d) or (e) of the proviso to Section 10.05 without the consent of the



                                       72

<PAGE>


Participant.  The Borrower  agrees that each  Participant  shall,  to the extent
provided in its participation  agreement, be entitled to the benefits of Article
8 with respect to its  participating  interest.  An assignment or other transfer
which is not permitted by subsection  (c) or (d) below shall be given effect for
purposes  of this  Agreement  only to the  extent  of a  participating  interest
granted in accordance with this subsection (b).

     (c) Any Bank may at any time,  upon five Business  Days' written  notice to
each of the Agents,  assign to one or more banks or other  institutions (each an
"Assignee") all, or a proportionate part (equivalent to an initial Commitment of
not less than  $2,500,000)  of all,  of its  rights and  obligations  under this
Agreement  and the  Notes,  and such  Assignee  shall  assume  such  rights  and
obligations, pursuant to an Assignment and Assumption Agreement in substantially
the form of Exhibit D hereto executed by such Assignee and such transferor Bank,
with  (and  subject  to)  the  subscribed   consent  of  the  Borrower  and  the
Administrative  Agent,  which  consent  shall in each  case not be  unreasonably
withheld;  provided  that (x) if an Assignee is an affiliate of such  transferor
Bank or was a Bank immediately  prior to such assignment or if the Assignee is a
Shareholder Guarantor purchasing Notes pursuant to Section 1(e) of a Shareholder
Guaranty,   no  such  consent   shall  be  required  and  (y)  such  Bank  shall
contemporaneously  assign to such  Assignee an  equivalent  percentage  of loans
under the Term Credit Agreement.  Upon execution and delivery of such instrument
and payment by such Assignee to such  transferor  Bank of an amount equal to the
purchase  price agreed  between such  transferor  Bank and such  Assignee,  such
Assignee  shall be a Bank party to this  Agreement and shall have all the rights
and  obligations of a Bank with a Commitment as set forth in such  instrument of
assumption,  and the  transferor  Bank shall be  released  from its  obligations
hereunder to a  corresponding  extent,  and no further  consent or action by any
party shall be required.  Upon the  consummation  of any assignment  pursuant to
this  subsection  (c), the  transferor  Bank, the  Administrative  Agent and the
Borrower shall make appropriate arrangements so that, if required, a new Note is
issued to the Assignee,  and the  transferor  Bank shall provide  prompt written
notice of such  assignment to the  Documentation  Agent.  In connection with any
such assignment,  the transferor Bank shall pay to the  Administrative  Agent an
administrative  fee for processing such  assignment in the amount of $2,500.  If
the Assignee is not incorporated  under the laws of the United States of America
or a state  thereof,  it shall  deliver to the Borrower  and the  Administrative
Agent  certification as to exemption from deduction or withholding of any United
States federal income taxes in accordance with Section 8.04.

     (d) Any Bank may at any time assign all or any portion of its rights  under
this Agreement and its Note to a Federal Reserve Bank. No such assignment  shall
release the transferor Bank from its obligations hereunder.



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<PAGE>



     (e) No Assignee, Participant or other transferee of any Bank's rights shall
be entitled to receive any greater  payment under Section 8.03 or 8.04 than such
Bank would have been entitled to receive with respect to the rights transferred,
unless such transfer is made with the  Borrower's  prior  written  consent or by
reason of the  provisions of Section 8.02,  8.03 or 8.04  requiring such Bank to
designate a different  Applicable Lending Office under certain  circumstances or
at a time when the  circumstances  giving rise to such  greater  payment did not
exist.

     (f) Each Bank shall, upon receipt from a Shareholder Guarantor of an amount
equal to all of such Bank's  Guaranteed  Obligations (as defined in the relevant
Shareholder  Guaranty)  (the  "Transfer  Payment"),  assign to such  Shareholder
Guarantor the  corresponding  portion of its rights and  obligations  under this
Agreement and the Notes in accordance  with paragraph (c) of this Section 10.06;
provided that (i) the consent of the Borrower and the Administrative Agent shall
not be  required  for  such  assignment  and  (ii) no such  assignment  shall be
effective until each Bank has received its Transfer  Payment from the applicable
Shareholder Guarantor.

     SECTION 10.07.  Collateral.  Each of the Banks represents to the Agents and
each of the other  Banks that it in good faith is not  relying  upon any "margin
stock"  (as  defined  in  Regulation  U)  as  collateral  in  the  extension  or
maintenance of the credit provided for in this Agreement.

     SECTION 10.08.  Governing Law;  Submission to Jurisdiction.  This Agreement
and each Note shall be governed by and construed in accordance  with the laws of
the State of New York.  Each of the  Borrower  and the Parent  Guarantor  hereby
submits to the nonexclusive jurisdiction of the United States District Court for
the Southern District of New York and of any New York State court sitting in New
York City for  purposes of all legal  proceedings  arising out of or relating to
this Agreement or the transactions contemplated hereby. Each of the Borrower and
the Parent Guarantor irrevocably waives, to the fullest extent permitted by law,
any objection  which it may now or hereafter  have to the laying of the venue of
any  such  proceeding  brought  in such a court  and any  claim  that  any  such
proceeding brought in such a court has been brought in an inconvenient forum.

     SECTION 10.09. Counterparts; Integration; Effectiveness. This Agreement may
be signed in any number of  counterparts,  each of which  shall be an  original,
with the same effect as if the signatures  thereto and hereto were upon the same
instrument.  This Agreement  constitutes the entire agreement and  understanding
among  the  parties  hereto  and  supersedes  any and all prior  agreements  and
understandings,  oral or written,  relating to the subject matter  hereof.  This



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<PAGE>


Agreement  shall become  effective  upon receipt by the  Documentation  Agent of
counterparts hereof signed by each of the parties hereto (or, in the case of any
party as to which an executed counterpart shall not have been received,  receipt
by the  Documentation  Agent in form  satisfactory to it of telegraphic,  telex,
facsimile  or other  written  confirmation  from such  party of  execution  of a
counterpart hereof by such party).

     SECTION  10.10.  Waiver of Jury  Trial.  EACH OF THE  BORROWER,  THE PARENT
GUARANTOR,  THE AGENTS AND THE BANKS HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT
TO TRIAL BY JURY IN ANY LEGAL  PROCEEDING  ARISING  OUT OF OR  RELATING  TO THIS
AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.

     SECTION  10.11.  Confidentiality.  Each  Bank  agrees  to take  normal  and
reasonable  precautions and exercise due care to maintain the confidentiality of
all non-public  information provided to it by the Parent Guarantor or any of its
Subsidiaries by the Agents on the Parent Guarantor's or such Subsidiary's behalf
in connection  with this Agreement or any other Loan Document and neither it nor
any of its Affiliates  shall use any such  information for any purpose or in any
manner other than pursuant to the terms  contemplated by this Agreement,  except
to the extent such  information  (a) was or becomes  generally  available to the
public other than as a result of a disclosure by the Bank, or (b) was or becomes
available  on a  non-confidential  basis  from a source  other  than the  Parent
Guarantor  or  the  Borrower,  provided  that  such  source  is not  bound  by a
confidentiality agreement with the Parent Guarantor or the Borrower known to the
Bank; provided,  further, that any Bank may disclose such information (A) to any
other Bank or to the Agents,  (B) at the request of any regulatory  authority or
in  connection  with an  examination  of such  Bank by any such  authority;  (C)
pursuant  to  subpoena or other  court  process;  (D) when  required to do so in
accordance  with  the  provisions  of any  applicable  law;  (E) at the  express
direction of any other agency of any State of the United States of America or of
any other jurisdiction in which such Bank conducts its business; and (F) to such
Bank's independent  auditors and legal counsel.  Notwithstanding  the foregoing,
the Company  authorizes  each Bank to disclose  to any  Participant  or Assignee
(each, a "Transferee")  and any prospective  Transferee such financial and other
information in such Bank's possession  concerning the Parent Guarantor or any of
its  Subsidiaries  which  has  been  delivered  to the  Banks  pursuant  to this
Agreement or which has been  delivered  to the Banks by the Parent  Guarantor or
any of its  Subsidiaries in connection with the Banks' credit  evaluation of the
Parent  Guarantor and its  Subsidiaries  prior to entering into this  Agreement;
provided  that  such  Transferee  agrees  in  writing  to such Bank to keep such
information confidential to the same extent required of the Banks hereunder.



                                       75

<PAGE>



     IN WITNESS  WHEREOF,  the parties  hereto have caused this  Agreement to be
duly  executed by their  respective  authorized  officers as of the day and year
first above written.

 
                                   AMSC ACQUISITION COMPANY, INC.

                                   By  /s/Gary M. Parsons
                                       ------------------

                                   Name:      Gary M. Parsons
                                   Title:     Chief Executive Officer,
                                              President and Treasurer
                                   Address:   10802 Parkridge Boulevard
                                              Reston, VA 20191
                                   Attention: General Counsel
                                   Facsimile: 703-758-6134


                                   AMERICAN MOBILE SATELLITE CORPORATION

                                   By  /s/Gary M. Parsons
                                       ------------------

                                   Name:      Gary M. Parsons
                                   Title:     President and Chief
                                              Executive Officer
                                   Address:   10802 Parkridge Boulevard
                                              Reston, VA 20191
                                   Attention: General Counsel
                                   Facsimile: 703-758-6134



                                       76

<PAGE>



                                   TORONTO DOMINION (TEXAS), INC.


                                   By  /s/Jano Mott
                                       ------------
                                   Name:      Jano Mott
                                   Title:     Vice President


                                   MORGAN GUARANTY TRUST
                                   COMPANY OF NEW YORK


                                   By  /s/John M. Mikolay
                                       ------------------
                                   Name:      John M. Mikolay
                                   Title:     Vice President


                                   BANK OF AMERICA NATIONAL
                                   TRUST AND SAVINGS
                                   ASSOCIATION


                                   By  /s/Robert W. Troutman
                                       ---------------------
                                   Name:      Robert W. Troutman
                                   Title:     Managing Director



                                       77

<PAGE>



                                   MORGAN GUARANTY TRUST
                                   COMPANY OF NEW YORK, as
                                   Documentation Agent


                                   By  /s/John M. Mikolay
                                       ------------------

                                   Name:      John M. Mikolay
                                   Title:     Vice President
                                   Address:   500 Stanton Christiana Road
                                              Newark, DE 19713
                                   Attention: Victoria Fedale
                                   Facsimile: 302-634-1852


                                   TORONTO DOMINION (TEXAS),
                                   INC., as Administrative Agent


                                   By  /s/Jano Mott
                                       ------------

                                   Name:      Jano Mott
                                   Title:     Vice President
                                   Address:   909 Fannin Street
                                              Houston, TX 77010
                                   Attention: Jano Mott
                                   Facsimile: 713-951-9921




                                       78

<PAGE>



                               COMMITMENT SCHEDULE

<TABLE>
<CAPTION>

              Bank                Tranche A       Tranche B       Tranche C
                                  Commitment      Commitment      Commitment
<S>                              <C>                      <C>     <C>       
Toronto Dominion (Texas),        $37,500,000              $0      $6,250,000
Inc.
Morgan Guaranty Trust            $37,500,000              $0      $6,250,000
Company of New York
Bank of America National                  $0     $12,500,000              $0
Trust and Savings
Association
</TABLE>





                                        1

<PAGE>



                                PRICING SCHEDULE

     "Euro-Dollar  Margin" and "Commitment Fee Percentage" mean for any date the
rates set forth below in the column  corresponding  to the "Pricing  Level" that
applies at such date:

<TABLE>
<CAPTION>


                        Level I           Level II           Level III
<S>                      <C>                <C>                 <C>   
Euro-Dollar Margin       0.500%             0.750%              1.000%
Commitment Fee           0.125%             0.150%              0.175%
Percentage
- ------------------     ---------          -----------        ------------
</TABLE>


     For  purposes of this  Schedule,  the  following  terms have the  following
meanings:

     "Level  I  Pricing"  applies  at any  date  if,  as of such  date,  Hughes'
long-term debt is rated A3 or higher by Moody's and A- or higher by S&P

     "Level II  Pricing"  applies at any date if, as of such date,  (i)  Hughes'
long-term  debt is rated Baa2 or higher by Moody's  and BBB or higher by S&P and
(ii) Level I Pricing does not apply.

     "Level III  Pricing"  applies  at any date if neither  Level I nor Level II
Pricing applies.

     "Moody's" means Moody's Investors Service, Inc.

     "Pricing Level" refers to the  determination  of which of Level I, Level II
or Level III applies at any date.

     "S&P" means Standard & Poor's Rating Service.

     The credit  ratings to be utilized for purposes of this  Schedule are those
assigned to the senior  unsecured  long-term  debt  securities of Hughes without
third-party  credit  enhancement,  and any  rating  assigned  to any other  debt
security of Hughes shall be  disregarded.  The ratings in effect for any day are
those in effect at the close of business on such day.


                                        1

<PAGE>



                               DISCLOSURE SCHEDULE


Section 1.01 -- FCC Licenses.



Section 4.03 -- Government Approvals.



Section 4.05 -- Litigation.



Section 4.07 -- Plans.



Section 4.10(c) -- Material Adverse Effect.



Section 4.13 -- Subsidiaries and Equity Investments.



Section 5.15 -- Existing Liens.



Section 5.23 -- Existing Indebtedness.








                                        1

<PAGE>



                                                              EXHIBIT A -- Note



                                 REVOLVING NOTE

                               New York, New York
                                                              [DATE]

     For value received,  AMSC Acquisition Company, Inc., a Delaware corporation
(the "Borrower"),  promises to pay to the order of  ______________________  (the
"Bank"),  for the account of its Applicable Lending Office, the unpaid principal
amount of each Loan made by the Bank to the Borrower  pursuant to the  Revolving
Credit  Agreement  referred to below on the  maturity  date  provided for in the
Revolving Credit Agreement.  The Borrower promises to pay interest on the unpaid
principal  amount  of each  such  Loan on the  dates  and at the  rate or  rates
provided for in the Revolving Credit  Agreement.  All such payments of principal
and interest  shall be made in lawful  money of the United  States in Federal or
other immediately available funds at the office of The Toronto-Dominion Bank, 31
West 52nd Street, New York, New York.

     All Loans made by the Bank, the respective Types thereof and all repayments
of the  principal  thereof  shall be  recorded  by the Bank and,  if the Bank so
elects in  connection  with any  transfer  or  enforcement  hereof,  appropriate
notations to evidence the foregoing  information  with respect to each such Loan
then outstanding may be endorsed by the Bank on the schedule attached hereto, or
on a continuation of such schedule attached to and made a part hereof;  provided
that the failure of the Bank to make any such  recordation or endorsement  shall
not affect the  obligations  of the Borrower  hereunder  or under the  Revolving
Credit Agreement.

     This note is one of the Notes referred to in the Revolving Credit Agreement
dated as of March 31, 1998 among AMSC Acquisition Company, Inc., American Mobile
Satellite Corporation, the banks party thereto, Morgan Guaranty Trust Company of
New  York,  as  Documentation  Agent  and  Toronto  Dominion  (Texas),  Inc.  as
Administrative  Agent  (as the  same  may be  amended  from  time to  time,  the
"Revolving Credit  Agreement").  Terms defined in the Revolving Credit Agreement
are used  herein  with the same  meanings.  Reference  is made to the  Revolving
Credit  Agreement for provisions for the prepayment  hereof and the acceleration
of the maturity hereof.


                                        1

<PAGE>



     The  payment  in full of the  principal  and  interest  on this  note  has,
pursuant  to  the   provisions  of  the   Revolving   Credit   Agreement,   been
unconditionally guaranteed by American Mobile Satellite Corporation.

                                 AMSC ACQUISITION COMPANY, INC.



                                 By --------------------------------------------

                                 Name:
                                 Title:



                                        2

<PAGE>




                         LOANS AND PAYMENTS OF PRINCIPAL

- --------------------------------------------------------------------------
           Amount           Type        Amount of
               of             of        Principal            Notation
Date         Loan           Loan          Repaid              Made By
- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------

- --------------------------------------------------------------------------



                                        3

<PAGE>



                EXHIBIT B -- Opinion of Counsel for the Borrower
                            and the Parent Guarantor

                                   OPINION OF
                            COUNSEL FOR THE BORROWER
                            AND THE PARENT GUARANTOR



                                                  March __, 1998


To the Banks, Shareholder Guarantors and the Agents
Referred to Below
c/o Morgan Guaranty Trust Company
of New York, as Documentation Agent
60 Wall Street
New York, New York  10260

Dear Sirs:

         I am Vice President,  Secretary and General Counsel of AMSC Acquisition
Company,  Inc., a Delaware corporation (the "Acquisition"),  and American Mobile
Satellite  corporation,  a Delaware Corporation (the "AMSC"). In such capacity I
have become  familiar with the  $100,000,000  Revolving  Credit  Agreement  (the
"Revolving Credit Agreement") among  Acquisition,  AMSC, the banks listed on the
signature  pages  thereof,  Morgan  Guaranty  Trust  Company  of  New  York,  as
Documentation Agent and Toronto Dominion (Texas),  Inc. as Administrative Agent.
Capitalized terms not otherwise defined herein shall have the meanings set forth
in the  Revolving  Credit  Agreement.  This  opinion  is being  rendered  to you
pursuant to Section 3.01 of the Revolving Credit Agreement.

         In rendering this opinion, I have examined originals or copies of:

1.       the Revolving Credit Agreement, the Notes and each Subsidiary
         Guaranty (collectively, the "Loan Documents");

2.       the certificates of incorporation, as amended, of AMSC, Acquisition and
         each Subsidiary of Acquisition (collectively, the "Loan Parties");

3.       the bylaws, as amended, of each Loan Party;



                                        1

<PAGE>



4.       the  Certificates  of Good  Standing  with  respect  to each Loan Party
         issued by the  Secretary  of State of the State of Delaware not earlier
         than March 20, 1998;

5.       the Certificate of Good Standing as a Foreign  Corporation with respect
         to AMSC issued by the State Corporation  Commission of the Commonwealth
         of Virginia dated March __, 1998;

6.       certain  resolutions  adopted  by the Board of  Directors  of AMSC at a
         meeting of the Board held on March 19, 1998;

7.       certain  resolutions  adopted by unanimous written consent of the Board
         of Directors of Acquisition dated March 19, 1998; and

8.       certain   resolutions  adopted  by  the  Board  of  Directors  of  each
         Subsidiary of  Acquisition at meetings of such Boards held on March 19,
         1998;

upon all of which I have relied. I have not  independently  verified any factual
matters in connection with or apart from my review of the documents  referred to
above and,  accordingly,  I do not express any opinion as to matters  that might
have been disclosed by independent verification.

         In arriving at the opinions  expressed  below, I have assumed,  and not
verified, the authenticity of all documents submitted to me as originals and the
conformity to original documents of all documents  submitted to me as copies, as
well as the due and valid  authorization,  execution  and  delivery  of all such
documents by the appropriate party or parties (other than the Loan Parties), and
that each such party  (other than the  applicable  Loan  Parties)  has  adequate
power,  authority and legal right to enter into such  documents to which it is a
party and to  perform  its  obligations  under such  documents  to which it is a
party.

         Based solely upon the foregoing and in reliance thereon, and subject to
the  qualifications,  limitations  and  assumptions  set forth herein,  it is my
opinion that:

         1. Each Loan Party is a corporation duly incorporated, validly existing
and in good  standing  under  the  laws of  Delaware  and,  in the  case of AMSC
Subsidiary Corporation, under the laws of Virginia, has all corporate powers and
all material  governmental  licenses,  authorizations,  consents  and  approvals
required to carry on its business as now  conducted,  and is duly qualified as a
foreign  corporation,  licensed  and in good  standing  under  the  laws of each
jurisdiction where its ownership,  lease or operation of property or the conduct
of its  business  require such  qualification  except where the failure to be so



                                        2

<PAGE>



qualified  would not  reasonably  be  expected  to result in a Material  Adverse
Effect.

         2. The  execution,  delivery and  performance  by AMSC of the Revolving
Credit Agreement, by Acquisition of the Revolving Credit Agreement and the Notes
and by each  Subsidiary of Acquisition  of the Subsidiary  Guaranties are within
the corporate powers of AMSC, Acquisition or such Subsidiary,  as relevant, have
been duly authorized by all necessary  corporate action and do not and will not:
(a) contravene the terms of such Person's  certificate of incorporation,  bylaws
or other  organization  documents;  (b) conflict with or result in any breach or
contravention  of, or the creation of any Lien under, any indenture,  agreement,
lease,  instrument,   Contractual  Obligation,   injunction,  order,  decree  or
undertaking to which such Person is a party;  or (c) violate any  Requirement of
Law.

         3.  Each  Loan  Document  constitutes  the  legal,  valid  and  binding
obligations or agreements of each Loan Party party thereto,  enforceable against
such Loan Party in accordance with its terms.

         4. Except as set forth in Section 4.05 of the  Disclosure  Schedule and
for matters  arising  after the  Effective  Date which could not  reasonably  be
expected  to have a  Material  Adverse  Effect,  there  are no  actions,  suits,
proceedings,  claims  or  disputes  pending,  or to the  best of our  knowledge,
threatened  or  contemplated  at law, in equity,  in  arbitration  or before any
Governmental Authority,  against AMSC or any of its Subsidiaries or any of their
respective  properties  which:  (a)  purport  to affect or  pertain  to any Loan
Document, or any of the transactions  contemplated thereby; or (b) if determined
adversely  to AMSC or any of its  Subsidiaries,  could have a  Material  Adverse
Effect.  No injunction,  writ,  temporary  restraining order or any order of any
nature has been issued by any court or other Governmental  Authority  purporting
to enjoin or  restrain  the  execution,  delivery  and  performance  of any Loan
Document,  or  directing  that the  transactions  provided  for  therein  not be
consummated as therein provided.

         5.  None of  AMSC,  any  Person  controlling  AMSC,  or any  Subsidiary
thereof,  is (a) an  "Investment  Company"  within the meaning of the Investment
Company  Act of 1940;  or (b)  subject to  regulation  under the Public  Utility
Holding Company Act of 1935, or, to the best of our knowledge, the Federal Power
Act, the Interstate  Commerce Act, any state public  utilities code or any other
Federal  or  state  statute  or   regulation   limiting  its  ability  to  incur
Indebtedness.



                                        3

<PAGE>



         The  foregoing  opinions are subject to the following  assumptions  and
qualifications:

         (a) The  opinions set forth in paragraph 3 are subject to the effect of
any applicable  bankruptcy,  insolvency,  reorganization,  moratorium or similar
laws  affecting  creditors'  rights  generally  and  to  the  possible  judicial
application of foreign laws or governmental  action affecting the enforcement of
creditors' rights.

         (b) The  opinions  set forth in  paragraph 3 are subject to the further
qualification  that the  enforceability  of the  obligations of the Loan Parties
under Loan Documents are subject to general  principles of equity (regardless of
whether such  enforceability is considered in a proceeding in equity or at law).
Such  principles  of equity are of general  application  and, in  applying  such
principles,  a  court,  among  other  things,  might  not  allow a  creditor  to
accelerate  the  maturity  of a debt upon the  occurrence  of a  default  deemed
immaterial  or might  decline  to  order  that a  covenant  be  performed.  Such
principles  applied by a court might include,  among other things, a requirement
that creditors act with  reasonableness and good faith. Such a requirement might
be applied,  among other  situations,  to the  provisions  of any Loan  Document
requiring  the payment of an indemnity or  compensation  to any party thereto or
purporting to authorize conclusive determinations by any party thereto.

         (c) Without  limiting the foregoing,  I call to your attention  certain
exceptions noted below.

                  (i) With  respect  to my  opinion  in  paragraph  3 hereof,  I
         express no opinion as to  whether  the courts of a  jurisdiction  other
         than the State of New York would give  effect to the choice of New York
         law as  governing  the  agreements  as to which I express an opinion in
         paragraph 3.

                  (ii) I express no opinion as to the possible  applicability to
         transactions  contemplated  by the Loan Documents of Section 548 of the
         United  States  Bankruptcy  Code  or  comparable  provisions  of  other
         applicable law.

                  (iii) With respect to my opinion in paragraph 3 hereof,

                         (A)  No  opinion  is  expressed  with  respect  to  the
                    enforceability   of  any  provision  in  Article  9  of  the
                    Revolving  Credit  Agreement or Section 5 of each Subsidiary
                    Guaranty  purporting to guarantee a liability of Acquisition





                                        4

<PAGE>

                    despite the fact that the obligations  being  guaranteed are
                    unenforceable  due to illegality or the fact that any one of
                    the Agents or any one of the Banks had voluntarily  released
                    Acquisition's  liability  with  respect  to such  guaranteed
                    obligations.

                         (B)  Section  9.02(a) and (b) of the  Revolving  Credit
                    Agreement  and  Section  5(a) of each  Subsidiary  Guaranty,
                    which  provide that the liability of AMSC or a Subsidiary of
                    Acquisition  shall  not  be  affected  by  certain  changes,
                    modifications,  amendments  or waivers  referred to therein,
                    might be  enforceable  only to the extent that such changes,
                    modifications, amendments or waivers were not so material as
                    to constitute a new contract among the parties.

                         (C) I express no opinion  as to the  enforceability  of
                    Section 9.04 of the Revolving  Credit Agreement or Section 6
                    of each Subsidiary Guaranty insofar as either of them relate
                    to any waiver or extension of or agreement not to assert any
                    defense based upon an applicable statue of limitations.

     (d) The  foregoing  opinions  are  limited  to the laws of the State of New
York,  the General  Corporation  Law of the State of  Delaware,  the laws of the
Commonwealth  of Virginia  and the Federal law of the United  States  (except as
noted below),  and I do not express any opinion herein  concerning any other law
(including,  without limitation,  any such other law of any jurisdiction wherein
any party to any of Loan  Document  may be located or deemed  located or wherein
enforcement of any such  documents may be sought).  I do not express any opinion
as to any matters arising under the Communications  Act of 1934, as amended,  or
any rules or  regulations  of the Federal  Communications  Commission.  I do not
express  any  opinion  as to  any  matters  (including  Governmental  Approvals)
relating  to  international  law,  including  compliance  by any Loan Party with
treaties  involving  the  International  Maritime  Satellite  Organization,  the
International  Telecommunications  Satellite  Organization and the International
Telecommunication  Union.  I am not a member of the Bar of the State of Delaware
and insofar as the opinions  expressed  herein  relate to matters of the General
Corporation  Law of the State of Delaware,  I have relied on the latest standard
compilations of statutes available to me.

     The  opinions  herein are  rendered as of the date of this  opinion,  and I
assume no obligation to revise or supplement this opinion at any date subsequent
hereto.


                                        5

<PAGE>



     The opinions  set forth above  relate  solely to the matters as to which my
opinion  has been  requested  by you,  and you must judge  whether  the  matters
addressed herein are sufficient for your purposes.  I do not express any opinion
as to any other matters.

     This opinion is rendered to the  Documentation  Agent and is solely for its
benefit, for the benefit of the Shareholder  Guarantors,  and for the benefit of
any Bank party to the Revolving  Credit  Agreement in connection  with the above
transaction.  This opinion may not be relied upon by the Documentation Agent for
any other purpose, or furnished to, quoted to or relied upon by any other Person
other than any Bank or  Shareholder  Guarantor  referred  to in the  immediately
preceding sentence,  for any purpose without my prior written consent. It is not
to be filed with or furnished to any  Governmental  Authority or other Person in
either case without my prior written consent.

                                            Very truly yours,


                                            /s/Randy S. Segal
                                            Randy S. Segal
                                            General Counsel


                                        6

<PAGE>



             EXHIBIT C -- Opinion of Special Counsel for the Agents


                                   OPINION OF
                             DAVIS POLK & WARDWELL,
                         SPECIAL COUNSEL FOR THE AGENTS


                                                        March __, 1998


To the Banks and the Agents
Referred to Below
c/o Morgan Guaranty Trust Company
of New York, as Documentation Agent
60 Wall Street
New York, New York  10260

Dear Sirs:

         We have  participated in the preparation of the $100,000,000  Revolving
Credit Agreement (the "Revolving  Credit  Agreement") dated as of March 31, 1998
among AMSC Acquisition Company,  Inc., a Delaware  corporation  ("Acquisition"),
American Mobile Satellite  Corporation,  a Delaware  corporation  ("AMSC"),  the
banks listed on the signature pages thereof (the "Banks"), Morgan Guaranty Trust
Company of New York, as Documentation Agent, and Toronto Dominion (Texas), Inc.,
as Administrative Agent (collectively,  the "Agents"), and have acted as special
counsel for the Agents for the purpose of  rendering  this  opinion  pursuant to
Section 3.01 of the Revolving Credit  Agreement.  Terms defined in the Revolving
Credit Agreement are used herein as therein defined.

         We have examined originals or copies, certified or otherwise identified
to our  satisfaction,  of such  documents,  corporate  records,  certificates of
public   officials  and  other   instruments   and  have  conducted  such  other
investigations  of fact and law as we have deemed  necessary  or  advisable  for
purposes of this opinion.

         Upon the basis of the  foregoing,  we are of the opinion that  assuming
that the  execution,  delivery and  performance  by Acquisition of the Revolving
Credit Agreement and the Notes and by AMSC of the Revolving Credit Agreement are
within  such  Person's  corporate  powers and have been duly  authorized  by all
necessary  corporate action, the Revolving Credit Agreement  constitutes a valid




                                        1

<PAGE>


and binding  agreement of Acquisition and AMSC and each Note constitutes a valid
and binding  obligation of Acquisition,  in each case  enforceable in accordance
with its terms  except as may be limited by  bankruptcy,  insolvency  or similar
laws affecting creditors' rights generally and by general principles of equity.

         We are  members  of the Bar of the State of New York and the  foregoing
opinion is limited to the laws of the State of New York. In giving the foregoing
opinion,  we  express  no  opinion  as to the  effect (if any) of any law of any
jurisdiction  (except the State of New York) in which any Bank is located  which
limits the rate of interest that such Bank may charge or collect.

         This  opinion is rendered  solely to you in  connection  with the above
matter.  This  opinion  may not be relied  upon by you for any other  purpose or
relied upon by any other person without our prior written consent.

                                            Very truly yours,



                                        2

<PAGE>



                EXHIBIT D -- Assignment and Assumption Agreement



                       ASSIGNMENT AND ASSUMPTION AGREEMENT

         AGREEMENT  dated as of  _________,  19__ among [NAME OF ASSIGNOR]  (the
"Assignor"), [NAME OF ASSIGNEE] (the "Assignee"), AMSC ACQUISITION COMPANY, INC.
(the "Borrower") and TORONTO DOMINION  (TEXAS),  INC., as  Administrative  Agent
(the "Agent").

         WHEREAS,  this  Assignment and Assumption  Agreement (the  "Agreement")
relates to the  $100,000,000  Revolving  Credit  Agreement dated as of March 31,
1998  among the  Borrower,  American  Mobile  Satellite  Corporation,  as Parent
Guarantor,  the Assignor  and the other Banks party  thereto,  as Banks,  Morgan
Guaranty Trust Company of New York, as  Documentation  Agent, and the Agent (the
"Credit Agreement");

         WHEREAS,  as provided  under the Credit  Agreement,  the Assignor has a
Commitment to make Loans to the Borrower in an aggregate principal amount at any
time outstanding not to exceed $__________;*

         WHEREAS,  Loans made to the Borrower by the  Assignor  under the Credit
Agreement in the aggregate  principal  amount of $__________  are outstanding at
the date hereof; and

         WHEREAS,  the  Assignor  proposes to assign to the  Assignee all of the
rights of the Assignor under the Credit Agreement in respect of a portion of its
Commitment thereunder in an amount equal to $__________ (the "Assigned Amount"),
together with a corresponding portion of its outstanding Loans, and the Assignee
proposes  to accept  assignment  of such  rights and  assume  the  corresponding
obligations from the Assignor on such terms;

         NOW,  THEREFORE,  in  consideration  of the  foregoing  and the  mutual
agreements contained herein, the parties hereto agree as follows:

         1.  Definitions.  All  capitalized  terms  not otherwise defined herein
shall have the respective meanings set forth in the Credit Agreement.

- --------
        1 To be modified if assignment occurs after Commitments have terminated.



                                        1

<PAGE>



         2.  Assignment.  The Assignor  hereby assigns and sells to the Assignee
all of the rights of the  Assignor  under the Credit  Agreement to the extent of
the Assigned  Amount,  and the Assignee  hereby accepts such assignment from the
Assignor and assumes all of the  obligations  of the  Assignor  under the Credit
Agreement to the extent of the Assigned Amount,  including the purchase from the
Assignor of the corresponding  portion of the principal amount of the Loans made
by the Assignor  outstanding at the date hereof. Upon the execution and delivery
hereof by the  Assignor,  the  Assignee,  [the  Borrower  and the Agent] and the
payment of the  amounts  specified  in Section 3 required to be paid on the date
hereof (i) the Assignee shall, as of the date hereof,  succeed to the rights and
be obligated  to perform the  obligations  of a Bank under the Credit  Agreement
with a  Commitment  in an  amount  equal to the  Assigned  Amount,  and (ii) the
Commitment of the Assignor  shall,  as of the date hereof,  be reduced by a like
amount and the Assignor released from its obligations under the Credit Agreement
to the extent such obligations have been assumed by the Assignee. The assignment
provided for herein shall be without recourse to the Assignor.

         3. Payments.  As consideration for the assignment and sale contemplated
in Section 2 hereof,  the Assignee  shall pay to the Assignor on the date hereof
in Federal funds the amount  heretofore  agreed  between them.* It is understood
that  commitment  and/or  facility  fees  accrued to the date hereof are for the
account of the  Assignor  and such fees  accruing  from and  including  the date
hereof  are for the  account  of the  Assignee.  Each  of the  Assignor  and the
Assignee hereby agrees that if it receives any amount under the Credit Agreement
which is for the account of the other party  hereto,  it shall  receive the same
for the account of such other party to the extent of such other party's interest
therein and shall promptly pay the same to such other party.

         [4.  Consent  of  the  Borrower  and  the  Agent.   This  Agreement  is
conditioned  upon the consent of the Borrower and the Agents pursuant to Section
10.06 of the Credit  Agreement.  The execution of this Agreement by the Borrower
and the Agents is  evidence  of this  consent.  Pursuant  to Section  2.03,  the
Borrower  agrees  to  execute  and  deliver a Note  payable  to the order of the
Assignee to evidence the assignment and assumption provided for herein.]

         5.  Non-Reliance on Assignor.  The Assignor makes no  representation or
warranty in connection with, and shall have no  responsibility  with respect to,
the  solvency, financial  condition, or statements of the Borrower or the Parent

- --------
         1 Amount should combine  principal  together with accrued  interest and
breakage compensation, if any, to be paid by the Assignee, net of any portion of
any upfront fee to be paid by the Assignor to the Assignee. It may be preferable
in an appropriate case to specify these amounts generically or by formula rather
than as a fixed sum.



                                        2

<PAGE>



Guarantor, or the validity and enforceability of the obligations of the Borrower
or the Parent  Guarantor  in respect of the Credit  Agreement  or any Note.  The
Assignee  acknowledges  that it has,  independently  and without reliance on the
Assignor,  and  based  on  such  documents  and  information  as it  has  deemed
appropriate,  made its own  credit  analysis  and  decision  to enter  into this
Agreement and will  continue to be  responsible  for making its own  independent
appraisal of the business, affairs and financial condition of the Borrower.

         6. Governing Law. This Agreement  shall be governed by and construed in
accordance with the laws of the State of New York.

         7.  Counterparts.  This  Agreement  may  be  signed  in any  number  of
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto and hereto were upon the same instrument.

         IN WITNESS  WHEREOF,  the  parties  have caused  this  Agreement  to be
executed and  delivered by their duly  authorized  officers as of the date first
above written.

                                  [NAME OF ASSIGNOR]


                                  By -------------------------------------------

                                  Name:
                                  Title:


                                  [NAME OF ASSIGNEE]


                                  By -------------------------------------------

                                  Name:
                                  Title:


                                  AMSC ACQUISITION COMPANY, INC.


                                  By -------------------------------------------

                                  Name:
                                  Title:





                                        3

<PAGE>



                                   TORONTO DOMINION (TEXAS), INC.,
                                   as Administrative Agent


                                   By ------------------------------------------

                                   Name:
                                   Title:




                                        4

<PAGE>



                         EXHIBIT E - Subsidiary Guaranty


                               SUBSIDIARY GUARANTY


TO:  Toronto Dominion (Texas), Inc.,
     as Administrative Agent


                             PRELIMINARY STATEMENTS:

         A.  AMSC  Acquisition  Company,   Inc.,  a  Delaware  corporation  (the
"Borrower"),  the Banks named  therein  (the  "Banks"),  Morgan  Guaranty  Trust
Company of New York, as Documentation Agent and Toronto Dominion (Texas),  Inc.,
as Administrative Agent (the "Agent"),  are parties to a $100,000,000  Revolving
Credit Agreement dated as of March 31, 1998 (said agreement, as it may hereafter
be amended,  supplemented,  restated or otherwise modified from time to time, is
referred to herein as the "Revolving Credit Agreement").

         B. The  undersigned  Guarantor  ("Guarantor")  is a  Subsidiary  of the
Borrower and it is a requirement  of the  Revolving  Credit  Agreement  that the
Guarantor enter into this Guaranty  guaranteeing all obligations of every nature
of the  Borrower  from time to time owed under or in  respect  of the  Revolving
Credit Agreement and the other Loan Documents (the "Guarantied Obligations").

         NOW, THEREFORE, the Guarantor agrees as follows:

         1.   For   valuable    consideration,    the   undersigned    Guarantor
unconditionally,  absolutely and  irrevocably  guarantees and promises to pay to
the Agent,  or order,  on  demand,  when due  (whether  by  scheduled  maturity,
required prepayment,  acceleration, demand, or otherwise) in lawful money of the
United States and in immediately  available funds, any and all present or future
Guarantied  Obligations  owing to the  Agents and the Banks  (collectively,  the
"Guarantied  Parties").  The term  Guarantied  Obligations is used herein in its
most comprehensive sense and include any and all advances,  debts,  obligations,
and liabilities of the Borrower,  now, or hereafter made, incurred,  or created,
whether  voluntary or  involuntarily,  and however arising,  including,  without
limitation,  any and all attorneys' fees, costs, premiums,  charges, or interest
owed by the Borrower to the Guarantied Parties, whether due or not due, absolute
or contingent, liquidated or unliquidated,  determined or undetermined,  whether
the Borrower may be liable individually or jointly with others, whether recovery




                                        1

<PAGE>


upon such  indebtedness  may be or  hereafter  becomes  barred by any statute of
limitations or whether such  indebtedness  may be or hereafter  become otherwise
unenforceable.

         2. Notwithstanding the foregoing, the liability of Guarantor under this
guaranty  shall be limited to an aggregate  amount  equal to the largest  amount
that would not render  its  obligations  hereunder  subject to  avoidance  under
Section 548 of the United States Bankruptcy Code or any comparable provisions of
any applicable state law.

         3.  This  Guaranty  is a  continuing  guaranty  which  relates  to  any
Guarantied Obligation, including those which arise under successive transactions
which  shall  either  cause the  Borrower to incur new  Guarantied  Obligations,
continue the Guarantied  Obligations from time to time, or renew them after they
have been  satisfied.  The  Guarantor  agrees that  nothing  shall  discharge or
satisfy its obligations created hereunder except for the full payment in cash of
the Guarantied Obligations with interest as applicable.

         4. The Guarantor agrees that it is directly liable to the Agent for the
benefit of the Guarantied  Parties for payment of the Guarantied  Obligations if
the Borrower  has failed to make payment  thereof when due (whether by scheduled
maturity,  required prepayment,  acceleration,  demand, or otherwise),  that its
obligations  hereunder are  independent  of the  Guarantied  Obligations  of the
Borrower,  or of any other guarantor,  and that a separate action or actions may
be brought and  prosecuted  against  the  Guarantor,  whether  action is brought
against the  Borrower  or whether  the  Borrower is joined in any such action or
actions.  The  Guarantor  agrees  that any  releases  which  may be given by the
Guarantied  Parties to the Borrower or any other  guarantor shall not release it
from this Guaranty.

         5. The  obligations  of the Guarantor  under this Guaranty shall not be
affected,  modified or impaired upon the occurrence  from time to time of any of
the following, whether or not with notice to or the consent of the Guarantor:

         (a)      the compromise, settlement, change, modification, amendment
(whether material or otherwise) or partial termination of any or all of the
Guarantied Obligations;

         (b) the failure to give notice to the  Guarantor of the  occurrence  of
any Event of Default under the terms and provisions of the Agreement;

         (c)      the waiver of the payment, performance or observance of any of
the Guarantied Obligations;



                                        2

<PAGE>



         (d) the taking or omitting  to take any  actions  referred to in any of
the Loan Documents or of any action under this Guaranty;

         (e) any  failure,  omission  or  delay  on the  part of the  Guarantied
Parties to enforce,  assert or exercise any right,  power or remedy conferred in
this Guaranty,  the Revolving Credit  Agreement,  any other Loan Document or any
other  indulgence or similar act on the part of the  Guarantied  Parties in good
faith and in compliance with applicable law;

         (f) the  voluntary or  involuntary  liquidation,  dissolution,  sale or
other  disposition  of all or  substantially  all of the assets,  marshalling of
assets,  receivership,  insolvency,  bankruptcy,  assignment  for the benefit of
creditors or  readjustment  of, or other  similar  proceedings  which affect the
Guarantor,  any other  guarantor  of any of the  Guarantied  Obligations  of the
Borrower or any of the assets of any of them, or any allegation of invalidity or
contest of the validity of this Guaranty in any such proceeding;

         (g) to the extent  permitted  by law,  the release or  discharge of any
other  guarantors  of  the  Guarantied   Obligations  from  the  performance  or
observance of any obligation,  covenant or agreement contained in any guaranties
of the Guarantied Obligations by operation of law; or

         (h) the default or failure of any other  guarantors  of the  Guarantied
Obligations  fully to perform any of their  respective  obligations set forth in
any such guaranties of the Guarantied Obligations.

         To the  extent any of the  foregoing  refers to any  actions  which the
Guarantied  Parties may take,  the Guarantor  hereby agrees that the  Guarantied
Parties may take such actions in such manner, upon such terms, and at such times
as the Guarantied Parties, in their discretion, deem advisable,  without, in any
way or respect, impairing,  affecting,  reducing or releasing the Guarantor from
its undertakings  hereunder and the Guarantor hereby consents to each and all of
the foregoing actions, events and occurrences.

         6. The Guarantor hereby waives:

         (a) any and all rights to require the  Guarantied  Parties to prosecute
or seek to enforce any  remedies  against the Borrower or any other party liable
to the Guarantied Parties on account of the Guarantied Obligations;

         (b) any right to assert  against  the  Guarantied  Parties any legal or
equitable  defense  (other than  indefeasible  payment in full of the Guarantied
Obligations or as expressly provided in this Guaranty),  set-off,  counterclaim,




                                        3

<PAGE>



or claim which the Guarantor may now or at any time  hereafter  have against the
Borrower  or any other  party  liable to the  Guarantied  Parties  in any way or
manner under the Revolving Credit Agreement;

         (c) all  defenses,  counterclaims  and  off-sets of any kind or nature,
arising  directly or indirectly  from the present or future lack of  perfection,
sufficiency,  validity or  enforceability  of any Loan Document and the security
interest granted pursuant thereto;

         (d) any defense arising by reason of any claim or defense based upon an
election of remedies by the Guarantied  Parties including,  without  limitation,
any direction to proceed by judicial or  nonjudicial  foreclosure  or by deed in
lieu thereof, which, in any manner impairs, affects, reduces, releases, destroys
or extinguishes the Guarantor's  subrogation  rights,  rights to proceed against
the Borrower for reimbursement,  or any other rights of the Guarantor to proceed
against  the  Borrower,  against  any  other  guarantor,  or  against  any other
security,  with the Guarantor  understanding that the exercise by the Guarantied
Parties of certain  rights and remedies may offset or eliminate the  Guarantor's
right of subrogation against the Borrower,  and that the Guarantor may therefore
incur partially or totally non-reimbursable liability hereunder; and

         (e)   all   presentments,   demands   for   performance,   notices   of
non-performance,  protests,  notices of protest, notices of dishonor, notices of
default,  notice of acceptance of this  Guaranty,  and notices of the existence,
creation, or incurring of new or additional indebtedness,  and all other notices
or formalities to which the Guarantor may be entitled.

         7. The  Guarantor  hereby  agrees that unless and until all  Guarantied
Obligations have been paid to the Guarantied  Parties in full, it shall not have
any rights of subrogation, reimbursement or contribution as against the Borrower
or any other  guarantor,  if any,  and shall not seek to assert or  enforce  the
same. The Guarantor  understands that the exercise by the Guarantied  Parties of
certain  rights  and  remedies  contained  in the Loan  Documents  may affect or
eliminate the Guarantor's  right of subrogation if any, against the Borrower and
that the Guarantor may therefore  incur a partially or totally  non-reimbursable
liability hereunder;  nevertheless, the Guarantor hereby authorizes and empowers
the  Guarantied  Parties to exercise,  in their sole  discretion,  any right and
remedy, or any combination thereof, which may then be available, since it is the
intent and purpose of the  Guarantor  that the  obligations  hereunder  shall be
absolute, independent and unconditional under any and all circumstances.

         8. The Guarantor is presently  informed of the  financial  condition of
the  Borrower  and of all other  circumstances  which a diligent  inquiry  would




                                        4

<PAGE>



reveal and which bear upon the risk of nonpayment of the Guarantied Obligations.
The Guarantor  hereby covenants that it will continue to keep itself informed of
the financial condition of the Borrower, the status of other guarantors, if any,
and of all  other  circumstances  which  bear upon the risk of  nonpayment.  The
Guarantor hereby waives its right, if any, to require the Guarantied  Parties to
disclose  to it  any  information  which  they  may  now  or  hereafter  acquire
concerning such condition or  circumstances  including,  but not limited to, the
release of any other guarantor.

         9. The Guarantied  Parties' books and records evidencing the Guarantied
Obligations shall be admissible in any action or proceeding and shall be binding
upon the Guarantor for the purpose of  establishing  the terms set forth therein
and shall constitute prima facie proof thereof.

         10. The  Guarantor  represents  and  warrants  for and with  respect to
itself that:

         (a) The Guarantor is a corporation  duly  organized and existing  under
the laws of the state of , and is properly licensed and in good standing in, and
where  necessary to maintain its rights and  privileges  have  complied with the
fictitious  name statute of, every  jurisdiction  in which it is doing business,
except  where the failure to be  licensed or be in good  standing or comply with
any such statute will not have a material  adverse  effect on the ability of the
Guarantor  to perform  its  obligations  hereunder  or under any  instrument  or
agreement required hereunder;

         (b) The  execution,  delivery and  performance of this Guaranty and any
instrument  or  agreement  required  hereunder  are  within  the  power  of  the
Guarantor,  have been duly authorized by, and are not in conflict with the terms
of any charter, by-law or other organization papers of, the Guarantor;

         (c) No approval, consent, exemption or other action by, or notice to or
filing with,  any  governmental  authority is necessary in  connection  with the
execution,  delivery,  performance  or  enforcement  of  this  Guaranty  or  any
instrument or agreement required hereunder, except as may have been obtained and
certified  copies of which  have  been  delivered  to Agent  and the  Guarantied
Parties;

         (d) There is no law,  rule or  regulation,  nor is there any  judgment,
decree or order of any court or governmental authority binding on the Guarantor,
which  would  be  contravened  by  the  execution,   delivery,   performance  or
enforcement of this Guaranty or any instrument or agreement required hereunder;


                                        5

<PAGE>



         (e) This  Guaranty  is a legal,  valid  and  binding  agreement  of the
Guarantor,  enforceable  against the Guarantor in accordance with its terms, and
any  instrument or agreement  required  hereunder,  when executed and delivered,
will  be  similarly  legal,  valid,   binding  and  enforceable,   except  where
enforceability  thereof may be limited by applicable law relating to bankruptcy,
insolvency,  moratorium  or  other  similar  laws  affecting  creditors'  rights
generally or by the application of general principles of equity;

         (f) There is no action,  suit or proceeding pending against,  or to the
knowledge  of the  Guarantor,  threatened  against or affecting  the  Guarantor,
before any court or  arbitrator  or any  governmental  body,  agency or official
which in any manner draws into question that validity or  enforceability of this
Guaranty; and

         (g) The  execution,  delivery and  performance by the Guarantor of this
Guaranty  does  not  constitute,  to the  best  knowledge  of the  Guarantor,  a
"fraudulent conveyance," "fraudulent obligation" or "fraudulent transfer" within
the meanings of the Uniform  Fraudulent  Conveyances  Act or Uniform  Fraudulent
Transfer Act, as enacted in any jurisdiction.

         11. Any one of the following events shall constitute a "Guarantor Event
of Default:"

         (a) The  Guarantor  is  generally  not paying or admits in writing  its
inability  to pay its debts as such debts  become due, or files any  petition or
action  for  relief  under  any  bankruptcy,   reorganization,   insolvency,  or
moratorium law or any other law for the relief of, or relating to, debtors,  now
or hereafter in effect, or makes any assignment for the benefit of creditors, or
takes any corporate action in furtherance of any of the foregoing;

         (b) An  involuntary  petition is filed against the Guarantor  under any
bankruptcy  statute  now or  hereafter  in  effect,  or a  custodian,  receiver,
trustee,  assignee for the benefit of creditors (or other  similar  official) is
appointed  to  take  possession,  custody  or  control  of any  property  of the
Guarantor,  unless such  petition or  appointment  is set aside or  withdrawn or
ceases to be in effect  within  sixty (60) days from the date of said  filing or
appointment.

THEN,  any and all of the  Guarantor's  obligations  under this  Guaranty  shall
become due,  payable and  enforceable  against the Guarantor  whether or not the
Guarantied  Obligations  are then due and payable without  presentment,  demand,
protest or other  requirements  of any kind,  all of which are hereby  expressly
waived by the Guarantor,  and the obligation of each Bank to make any Loan under
the Revolving Credit Agreement shall thereupon terminate.



                                        6

<PAGE>



         12. This Guaranty  shall be binding upon the  successors and assigns of
the  Guarantor  and  shall  inure  to the  benefit  of the  Guarantied  Parties'
successors  and  assigns.  This  Guaranty  cannot be assigned  by the  Guarantor
without the prior written  consents of the Guarantied  Parties which shall be in
the Guarantied Parties' sole and absolute discretion.

         13. No failure or delay by the  Guarantied  Parties in  exercising  any
right, power or privilege  hereunder shall operate as a waiver thereof nor shall
any single or partial  exercise  thereof  preclude any other or further exercise
thereof or the exercise of any other right,  power or privilege.  The rights and
remedies  herein provided shall be cumulative and not exclusive of any rights or
remedies provided by law.

         14. The Guarantor shall pay all out-of-pocket  expenses incurred by the
Agent and the Guarantied  Parties,  including fees and  disbursements of counsel
(including the allocated cost of inhouse counsel and staff),  in connection with
the enforcement of this Guaranty (whether or not suit is brought).

         15. No modification of this Guaranty shall be effective for any purpose
unless  it is in  writing  and  executed  by an  officer  of the  Agent  and the
Guarantor   authorized  to  do  so.  This  Guaranty  merges  all   negotiations,
stipulations  and  provisions  relating to the subject  matter of this  Guaranty
which preceded or may accompany the execution of this Guaranty.

         16.  This  Guaranty  and the  rights  and  obligations  of the  parties
hereunder  shall be construed in accordance  with and be governed by the laws of
the State of New York without  reference to the  principles of conflicts of laws
thereof.

         17. This Guaranty may be executed in any number of counterparts  and by
the different  parties  hereto on separate  counterparts,  each of which when so
executed and  delivered  shall be an original,  but all of which shall  together
constitute one and the same instrument.

         18. Any  indebtedness  of the  Borrower  now or  hereafter  held by the
Guarantor  is hereby  subordinated  to the  indebtedness  of the Borrower to the
Agent and the Guarantied  Parties;  and such indebtedness of the Borrower to the
Guarantor if the Agent so requests shall be collected,  enforced and received by
the  Guarantor as trustee for the Agent and the  Guarantied  Parties and be paid
over to the Agent on account of the  indebtedness  of the  Borrower to the Agent
and the Guarantied  Parties but without  reducing or affecting in any manner the
liability of the Guarantor under the other provisions of this Guaranty.



                                        7

<PAGE>



         19. This Guaranty shall become  effective upon execution  hereof by the
Guarantor.  The Guarantor  shall deliver to the Agent all of the  following,  in
form and  substance  satisfactory  to the Agent and the Banks and in  sufficient
copies for each Bank:

         (a)      Resolutions; Incumbency Certificate.

                           (i)  Copies  of  the  resolutions  of  the  board  of
                  directors  of the  Guarantor  approving  and  authorizing  the
                  execution,  delivery and  performance  of this Guaranty by the
                  Guarantor, certified as of the date hereof by the Secretary or
                  an Assistant Secretary of the Guarantor; and

                           (ii) A  certificate  of the  Secretary  or  Assistant
                  Secretary  of the  Guarantor  certifying  the  names  and true
                  signatures  of the  officers of the  Guarantor  authorized  to
                  execute and deliver this Guaranty.

         (b)  Articles  of  Incorporation;  By-laws  and  Good  Standing  of the
Guarantor. Each of the following documents:

                           (i) the articles or certificate of  incorporation  of
                  the  Guarantor as in effect on the date  hereof,  certified by
                  the  Secretary of State of the State of  incorporation  of the
                  Guarantor  as  of a  recent  date  and  by  the  Secretary  or
                  Assistant Secretary of the Guarantor as of the date hereof and
                  the bylaws of the  Guarantor  as in effect on the date hereof,
                  certified  by the  Secretary  or  Assistant  Secretary  of the
                  Guarantor as of the date hereof; and

                           (ii) a good  standing  certificate  for the Guarantor
                  from the Secretary of State of its state of incorporation  and
                  each state where the  Guarantor is qualified to do business as
                  a foreign corporation as of a recent date.

         20. Unless otherwise specified herein or therein,  all terms defined in
this  Guaranty  shall have  meanings  assigned to them in the  Revolving  Credit
Agreement.

         21. All notices and other communications  hereunder shall be delivered,
in the manner and with the effect  provided in the  Revolving  Credit  Agreement
and, in the case of the Guarantor, care of the Borrower.




                                        8

<PAGE>



         22. It is not necessary for the Guarantied  Parties to inquire into the
powers of any Guaranteed Party or of the officers, directors or agents acting or
purporting  to act on its  behalf,  and  any  indebtedness  made or  created  in
reliance  upon  the  professed  exercise  of such  powers  shall  be  guaranteed
hereunder.

         Executed as of the      day of         ,      .

                       [Guarantor]

                       By:        --------------------------------------------

                       Title:     --------------------------------------------



TORONTO DOMINION (TEXAS), INC.,
  as Administrative Agent



By: -------------------------------------






                                       9

<PAGE>



                                  EXHIBIT 11.1

                      AMERICAN MOBILE SATELLITE CORPORATION
                     ---------------------------------------
                    COMPUTATIONS OF EARNINGS PER COMMON SHARE
                     ---------------------------------------
                    (in thousands, except per share amounts)
                     ---------------------------------------

<TABLE>
<CAPTION>

                                                                   Three Months
                                                                  Ended March 31,

                                                                1998           1997
                                                                ----           ----
BASIC EARNINGS PER SHARE CALCULATION
- ------------------------------------

<S>                                                        <C>               <C>      
Net Loss                                                   ($25,242)         ($27,081)
                                                           =========         =========

Net Loss per common share                                    ($1.00)           ($1.08)
                                                             =======           =======

Weighted-average common shares                               25,241            25,109
                                                             =======           ======


DILUTED EARNINGS PER SHARE CALCULATION
- --------------------------------------
Net Loss                                                   ($25,242)         ($27,081)
                                                           =========         =========

Net Loss per common share                                    ($1.00)           ($1.08)
                                                             =======           =======

Weighted-average common shares (1)                           25,336            25,188
                                                             ======            ======



(1)  Calculated as follows:
      Historical weighted average number of
          shares outstanding                                 25,241            25,109
      Assumed exercise of stock options                          33                17
      Assumed exercise of stock purchase                         62                62
                                                           --------           -------

                                                             25,336            25,188
                                                             ======           =======


</TABLE>


<PAGE>



<TABLE> <S> <C>


<ARTICLE>                               5
<LEGEND>
     This schedule  contains summary  financial  information  extracted from the
     Company's unaudited  Consolidated  Statement of Loss,  Consolidated Balance
     Sheet, and Consolidated Statement of Cash Flows, in each case for the three
     months ended March 31, 1998, and is qualified in its entirety by reference
     to such financial statements.
</LEGEND>
<MULTIPLIER>                             1,000
<CURRENCY>                               U.S. Dollars
       
<S>                                      <C>
<PERIOD-TYPE>                            3-MOS
<FISCAL-YEAR-END>                        DEC-31-1998
<PERIOD-START>                           JAN-01-1998
<PERIOD-END>                             MAR-31-1998
<EXCHANGE-RATE>                                1
<CASH>                                    21,279
<SECURITIES>                             124,000
<RECEIVABLES>                             11,477
<ALLOWANCES>                                   0
<INVENTORY>                               41,038
<CURRENT-ASSETS>                         136,525
<PP&E>                                   264,261
<DEPRECIATION>                                 0
<TOTAL-ASSETS>                           585,528
<CURRENT-LIABILITIES>                     61,733
<BONDS>                                  465,706
                          0
                                    0
<COMMON>                                     317
<OTHER-SE>                                80,677
<TOTAL-LIABILITY-AND-EQUITY>             585,528
<SALES>                                    3,604
<TOTAL-REVENUES>                          10,022
<CGS>                                      3,881
<TOTAL-COSTS>                             18,262
<OTHER-EXPENSES>                          10,163
<LOSS-PROVISION>                               0
<INTEREST-EXPENSE>                         6,638
<INCOME-PRETAX>                          (25,242)
<INCOME-TAX>                                   0
<INCOME-CONTINUING>                      (25,242)
<DISCONTINUED>                                 0
<EXTRAORDINARY>                                0
<CHANGES>                                      0
<NET-INCOME>                             (25,242)
<EPS-PRIMARY>                              (1.00)
<EPS-DILUTED>                                  0
        


</TABLE>


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