AMERICAN MOBILE SATELLITE CORP
SC 13D/A, 1996-07-15
COMMUNICATIONS SERVICES, NEC
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                                UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                           Washington, D.C.  20549

                                 SCHEDULE 13D

                  UNDER THE SECURITIES EXCHANGE ACT OF 1934
                              (AMENDMENT NO. 2)*

                    American Mobile Satellite Corporation
 _____________________________________________________________________________
                        ______________________________
                               (Name of Issuer)

                         Common Stock $.01 Par Value
 _____________________________________________________________________________
                        ______________________________
                        (Title of Class of Securities)

                                 02755R 10 3
             ____________________________________________________
                                (CUSIP Number)
  Ms. Chan Su Shan, Company Secretary, Singapore Telecommunications Limited
      31 Exeter Road, Comcentre, Singapore 239732, Republic of Singapore
                           (011) (65) 838-2201 */
 _____________________________________________________________________________
                        ______________________________
                (Name, Address and Telephone Number of Person
              Authorized to Receive Notices and Communications)

                                 July 1, 1996
 _____________________________________________________________________________
                                    ______
           (Date of Event which Requires Filing of this Statement)



If  the  filing  person  has  previously  filed a statement on Schedule 13G to
report  the  acquisition  which  is  the  subject of this Schedule 13D, and is
filing  this  schedule because of Rule 13d-1(b)(3) or (4), check the following
box [  ] .

Check  the  following box if a fee is being paid with the statement[ ].  (A fee
is  not required only if the reporting person: (1) has a previous statement on
file  reporting beneficial ownership of more than five percent of the class of
securities  described  in  Item  1;  and (2) has filed no amendment subsequent
thereto reporting beneficial ownership of five percent or less of such class.)
 (See Rule 13d-7.)

Note:  Six  copies  of this statement, including all exhibits, should be filed
with  the  Commission.  See Rule 13d-1(a) for other parties to whom copies are
to be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial  filing  on this form with respect to the subject class of securities,
and  for  any  subsequent  amendment  containing information which would alter
disclosures provided in a prior cover page.

The  information  required  on  the  remainder of this cover page shall not be
deemed  to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the  Act but shall be subject to all other provisions of the Act (however, see
the Notes).

*/          With a copy to:  Phillip L. Spector, Esq., Paul, Weiss, Rifkind,
Wharton  &  Garrison,  1615 L Street, N.W., Suite 1300, Washington, DC  20036,
(202) 223-7340.

<PAGE>

                                 SCHEDULE 13D

CUSIP No.  02755R 10 3                                   Page    2  of    Pages

1     NAME OF REPORTING PERSON
      S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

      Singapore Telecommunications Limited

2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                  (a)[ ]
                                                                        (b)[X]


3     SEC USE ONLY


4     SOURCE OF FUNDS

           WC

5     CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
      ITEMS 2(d) or 2(e)                                                   [ ]




6     CITIZENSHIP OR PLACE OF ORGANIZATION

     Republic of Singapore

          7     SOLE VOTING POWER
         
                     4,512,796  shares  (if  the Issuer's Warrant dated 6/28/96
                     were exercisable in full:  4,731,546)
NUMBER OF
SHARES
BENEFICIALLY OWNED
BY EACH REPORTING
PERSON
WITH
          8     SHARED VOTING POWER

                        0 shares

          9     SOLE DISPOSITIVE POWER
         
                     4,512,796  shares  (if  the Issuer's Warrant dated 6/28/96
                     were exercisable in full:  4,731,546)

          10     SHARED DISPOSITIVE POWER

                        0 shares

11     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4,512,796  shares (if the Issuer's Warrant dated 6/28/96 were
            exercisable in full:  4,731,546)

12     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES [X]


13     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

           17.8%  (if  the Issuer's Warrant dated 6/28/96 were exercisable in
           full: 18.5%)

14     TYPE OF REPORTING PERSON

            CO

<PAGE>
                                 SCHEDULE 13D

CUSIP No.  02755R 10 3                                   Page    3  of    Pages

1     NAME OF REPORTING PERSON
      S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

      Temasek Holdings (Private) Limited

2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                  (a)
                                                                        (b)[x]

3     SEC USE ONLY


4     SOURCE OF FUNDS

           AF

5     CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
      ITEMS 2(d) or 2(e)                                                   [ ]


6     CITIZENSHIP OR PLACE OF ORGANIZATION

           Republic of Singapore

          7     SOLE VOTING POWER

               4,512,796  shares  (if  the Issuer's Warrant dated 6/28/96 were
               exercisable in full:  4,731,546)

NUMBER OF
SHARES
BENEFICIALLY OWNED
BY EACH REPORTING
PERSON
WITH
          8     SHARED VOTING POWER

                  0 shares

          9     SOLE DISPOSITIVE POWER

               4,512,796  shares  (if  the Issuer's Warrant dated 6/28/96 were
               exercisable in full:  4,731,546)

          10    SHARED DISPOSITIVE POWER

                  0 shares

11     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        4,512,796  shares (if the Issuer's Warrant dated 6/28/96 were
        exercisable in full:  4,731,546)

12     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES [X]


13     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

         17.8%  (if  the Issuer's Warrant dated 6/28/96 were exercisable in
         full: 18.5%)

14     TYPE OF REPORTING PERSON
 
        HC

<PAGE>
                                                                              4

                            AMENDED SCHEDULE 13D {1/}


Item 3.  Source and Amount of Funds or Other Consideration

          Item 3 is amended and restated in its entirety as follows:

          Prior  to  November  1992,  all  of  Singapore Telecom's holdings of
Common Stock were held indirectly through Mtel Space Technologies, L.P. ("Mtel
L.P."),  a Delaware partnership in which Singapore Telecom's legal predecessor
was  a limited partner until November 1992.{2/}  The sole assets of Mtel L.P.
were shares of Common Stock.  Singapore Telecom provided funds to Mtel L.P. both
by purchasing  limited  partnership  units  in  Mtel  L.P.  ("Mtel  LPUs") and
by purchasing  convertible  debentures issued by Mtel L.P. (the "Mtel
Convertible Debentures").    The  Mtel  Convertible  Debentures  were,  subject
to certain conditions,  convertible  into  Mtel  LPUs  which, upon conversion,
were to be redeemed immediately for shares of Common Stock held of record by
Mtel L.P.

          At  the  time Mtel L.P. was restructured in November 1992, Singapore
Telecom  had  contributed $6,667,000 to Mtel L.P. through the purchase of Mtel
LPUs  and  had  loaned  Mtel  L.P.  $24,266,355  through  the purchase of Mtel
Convertible  Debentures.    All  such  funds  came from the working capital of
Singapore Telecom.

          As  part  of  the  Mtel  L.P.  restructuring,  all Mtel LPUs held by
Singapore  Telecom  were redeemed for shares of Common Stock, and a portion of
the  Mtel  Convertible  Debentures  held by Singapore Telecom were converted. 
After  the  restructuring,  Singapore  Telecom held directly 467,810 shares of
Common  Stock  (equivalent  to  1,116,363  shares  of  Common  Stock after the
December  1993  stock  split  by  the Issuer).  In addition, Singapore Telecom
continued  to hold $14,660,015 principal amount of Mtel Convertible Debentures
that,  upon conversion into Mtel LPUs, were to be redeemed immediately by Mtel
L.P.  for  318,841  shares (760,869 post-split shares) of Common Stock held of
record by Mtel L.P.

          On  December 20, 1993, Singapore Telecom engaged in the transactions
that  required  the  filing  of an initial statement on Schedule 13D.  On that
date,  Singapore  Telecom  purchased  from the issuer 911,854 shares of Common
Stock  for  a

- ----------------------------
{1/}
Amending the Amended and Restated Schedule 13D dated December 28, 1995.

{2/}
In  April  1992,  pursuant to the Telecommunication Authority of Singapore Act
1992, Singapore Telecom became the successor in interest to telecommunications
businesses  owned  by  the  Telecommunication  Authority  of  Singapore (which
continues  to  exercise  regulatory  oversight over those businesses).  Unless
otherwise  indicated by the context, "Singapore Telecom" will be used to refer
both to Singapore Telecommunications Limited and to its legal predecessor.


<PAGE>
                                                                              5
cash purchase price of $18 million.  The funds used to make this
purchase came from the working capital of Singapore Telecom.

          On that same date, 1,317,460 shares were issued to Singapore Telecom
by  the  Issuer  upon conversion by Singapore Telecom of $27,666,677 principal
amount  of  subordinated  convertible notes previously issued by the Issuer to
Singapore  Telecom.    The  Singapore  Telecom  funds  loaned to the Issuer in
connection  with  such  convertible  notes  ($20  million  in  August 1992 and
$7,666,667  in  October  1993)  came  from  the  working  capital of Singapore
Telecom.

          In  December 1995, Singapore Telecom delivered to Mtel L.P. a notice
of conversion with respect to the remaining Mtel Convertible Debentures.  Upon
conversion, Singapore Telecom received 8451.71 Mtel LPUs that, as noted above,
were to be redeemed immediately by Mtel L.P. in exchange for 760,869 shares of
Common  Stock  held  of  record  by Mtel L.P.  On December 27, 1995, Mtel L.P.
redeemed the 8451.71 Mtel LPUs and directed the Issuer to transfer the 760,869
shares of Common Stock to Singapore Telecom (effective as of that date).

          On  July  1, 1996, upon the closing of a set of agreements providing
long-term  bank financing for the Issuer, Singapore Telecom received a warrant
from  the Issuer entitling it to purchase 625,000 shares of Common Stock at an
initial  exercise  price  of  $24  per share (the "Warrant").  The Warrant was
received  as  part of the consideration for Singapore Telecom's guaranty of up
to $25 million in principal amount of such long-term financing.  The number of
shares  of  Common  Stock for which the Warrant may be exercised is limited to
the  extent  that  certain  financial  performance tests restrict the Issuer's
ability  to  borrow  fully  under  the long-term loan agreements (as described
under  Item 6 below).  As of July 1, 1996, the Warrant is exercisable for only
406,250 shares of Common Stock.

          To  the  best  knowledge of the Reporting Persons, the funds used by
the  persons  listed  in  Schedules  I and II to purchase the shares of Common
Stock specified in Item 5 below came from personal savings of such persons.

Item 4.     Purpose of Transaction

          Item 4 is amended and restated in its entirety as follows:

          The  shares  of Common Stock held by Singapore Telecom were acquired
for  investment purposes, and continue to be held for such purposes.  Pursuant
to  the  cumulative voting rights that exist under the Issuer's Certificate of
Incorporation with respect to the election of the Issuer's board of directors,
and  pursuant  to  the  rights  that  exist  under the Stockholders' Agreement
(described  in  Item  6  below)  with  respect  to appointing directors to the
executive  committee of the Issuer's board of directors, Singapore Telecom has
the  right  to  be  represented  on  the  Issuer's  board of directors and its
executive  committee.   Singapore Telecom presently has two representatives on
the  Issuer's  board  of  directors  and  one  representative  on the Issuer's
executive  committee.  Singapore Telecom representatives also participate in
other committees of the Issuer's board of directors.  

<PAGE>
                                                                              6

          The  ability of Singapore Telecom to acquire or dispose of shares of
Common  Stock  is  limited  to some degree by certain agreements, as described
under  Item  6 below.  Subject to such agreements, Singapore Telecom may, from
time  to  time, make additional purchases of Common Stock of the Issuer either
in  the  open  market  or  in  private  transactions, depending upon Singapore
Telecom's  evaluation  of  the  Issuer's  business,  prospects,  and financial
condition,  the market for the Common Stock of the Issuer, other opportunities
available  to  Singapore Telecom, general economic conditions, money and stock
market  conditions,  regulatory approvals or restrictions, and other factors. 
Depending  upon  these  factors,  and  subject  to  such agreements, Singapore
Telecom may also decide to hold or dispose of all or part of its investment in
the Common Stock of the Issuer.

          Except  as  described  herein, the Reporting Persons have no present
plan or proposal that relates to or would result in:

(a)      the acquisition by any person of additional securities of the Issuer,
or the disposition of securities of the Issuer;

(b)      an  extraordinary  corporate  transaction,  such  as  a  merger,
reorganization,  or  liquidation,  involving  the  Issuer  or  any  of  its
subsidiaries;

(c)      a sale or transfer of a material amount of assets of the Issuer or any
of its subsidiaries;

(d)      any change in the present board of directors or management of the
Issuer;

(e)      any material change in the present capitalization or dividend policy
of the Issuer;

(f)      any  other  material change in the Issuer's business or corporate
structure;

(g)      changes in the Issuer's charter or bylaws or other actions which may
impede the acquisition of control of the Issuer by any person;

(h)      any act or course of conduct causing the Common Stock of the Issuer to
cease  to  be authorized to be quoted in an inter-dealer quotation system of a
registered national securities association;

(i)      any act or course of conduct causing the Common Stock of the Issuer to
become  eligible  for termination of registration pursuant to Section 12(g)(4)
of the Securities Exchange Act of 1934 (the "Act"); or

(j)      any action similar to any of those enumerated above.

          The  Reporting  Persons reserve the right to formulate such plans or
proposals,  and  to  take  such  action,  with  respect  to  any or all of the
foregoing matters and any other matters as they may deem appropriate.


<PAGE>
                                                                              7
                                       


          To  the  best  knowledge  of  the  Reporting  Persons,  all  shares
identified  in  Item  5  below  as  beneficially  owned  by  persons listed in
Schedules  I  and  II  were acquired by such persons for investment purposes. 
Such persons may buy or sell shares of Common Stock in the future as they deem
appropriate,  but,  to the best knowledge of the Reporting Persons, and except
as  otherwise  indicated herein, such persons have no present plan or proposal
that  relates  to  or  would  result in the actions or events specified in (a)
through (j) above.

Item 5.     Interest in Securities of the Issuer

          Item 5 is amended and restated in its entirety as follows:

(a)     Singapore Telecom owns beneficially 4,512,796 shares of Common Stock. 
Of  this  amount,  4,106,546  shares  of  Common  Stock are owned of record by
Singapore  Telecom,  and  406,250  shares of Common Stock could be obtained by
Singapore Telecom upon exercise of the Warrant.  If the Warrant were presently
exercisable  in full, Singapore Telecom would be able to obtain 625,000 shares
of  Common  Stock  upon exercise of the Warrant, and Singapore Telecom's total
beneficial  ownership  would  be  4,731,546  shares  of  Common  Stock.   (The
restrictions  upon exercise of the Warrant are described in Item 6 below.)  By
reason  of  its ownership stake in Singapore Telecom, Temasek may be deemed to
be  the  beneficial  owner of the shares of Common Stock beneficially owned by
Singapore Telecom.

          Based upon the information contained in the Issuer's Form 10-Q dated
May  14,  1996,  the  4,512,796  shares  of Common Stock beneficially owned by
Singapore  Telecom  constitute  approximately  17.8%  of  the  Common  Stock
outstanding  as  of March 31, 1996.{3/} If the Warrant were presently
exercisable in full, the 4,731,546 shares of Common Stock that would be
beneficially owned by  Singapore Telecom would constitute approximately 18.5% of
the Common Stock outstanding as of March 31, 1996.{4/}

          To  the best knowledge of the Reporting Persons, none of the persons
listed  in  Schedule  I  or  II  beneficially own or have the right to acquire
shares of Common Stock of the Issuer, except as set forth in the table below:


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

{3/}
For  the  purpose  of  computing this percentage, the Warrant was deemed to be
exercised  to the extent presently exercisable, and the shares of Common Stock
issuable upon such exercise were deemed to be outstanding.

{4/}
For  the  purpose  of  computing this percentage, the Warrant was deemed to be
fully  exercisable  and  exercised  in  full,  and  the shares of Common Stock
issuable upon such exercise were deemed to be outstanding.

<PAGE>
                                                                              8

   Name of
Beneficial Owner        Number of Shares           Percentage


Lim Toon                   2,000                      */

Raphael Leong Sai Mooi     1,000                      */

Chua Sock Koong            5,000                      */


*/   Less than 0.1%

          The  Reporting Persons may be deemed to comprise a group (within the
meaning  of Section 13(d)(3) of the Act) with the following entities by virtue
of  certain  agreements  described  in  Item  6 below:  (1) Hughes Electronics
Corporation  ("Hughes  Electronics")  and  Hughes  Communications  Satellite
Services,  Inc.  ("Hughes"  and, together with Hughes Electronics, the "Hughes
Entities"), an indirect wholly-owned subsidiary of Hughes Electronics; and (2)
Space Technologies Investments ("Investments") and the following affiliates of
Investments:    Transit  Communications,  Inc.,  and  Satellite Communications
Investments Corporation (collectively with Investments, the "AT&T Entities").
{5/}

          The Reporting Persons expressly disclaim beneficial ownership of the
shares  of Common Stock held by the Hughes Entities and the AT&T Entities, and
the  filing  of this statement by the Reporting Persons shall not be construed
as  an admission by the Reporting Persons that either of them is, for purposes
of  Section  13(d)  of  the  Act, the beneficial owner of any of the shares of
Common Stock held by the Hughes Entities or the AT&T Entities.

          Based upon the information set forth in the Issuer's Proxy Statement
dated  April 1, 1996 and the Issuer's Form 10-Q dated March 31, 1996, and upon
additional information received from the Issuer, the Reporting Persons believe
that  the Hughes Entities and the AT&T Entities beneficially own the number of
shares  of  Common  Stock  of  the  Issuer  set  forth  in  the  table  below,
constituting  in  each case that percentage of the outstanding Common Stock of
the Issuer set forth in the table:

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

{5/}
Prior  to  the  conversion  of  the  remaining  Mtel Convertible Debentures in
December  1995,  and  the  resulting  transfer of the 760,869 shares of Common
Stock  from  Mtel L.P. to Singapore Telecom, the following entities might also
have been deemed to be part of such group:  Mtel L.P., Mtel Space Technologies
Corporation  ("Mtel  Corp.")  (Mtel  L.P.'s  general  partner),  and  Mtel
Technologies,  Inc.  ("Mtel  Corp.  Affiliate")  (Mtel L.P.'s limited partner)
(collectively, the "Mtel Group").

<PAGE>
                                                                              9
Name of Beneficial Owner          Number of Shares     Percentage{6/}


Hughes Communications
  Satellite Services, Inc.{7/}      6,691,622          26.73

Hughes Electronics Corporation{8/}  2,437,500          8.88

      Hughes Entities as a Group    9,129,122          33.23

- ---------------------------------------------------------------------------- -
Space Technologies
  Investments, Inc.{9/}             1,855,539          7.23

Transit Communications, Inc.          681,818          2.73

Satellite Communications
  Investments Corporation{9/}.      1,344,067          5.32

     AT&T Entities as a Group       3,881,424         14.99

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

{6/}
For  the purpose of computing the percentage of the Common Stock of the Issuer
beneficially owned by the entities listed here, warrants held by such entities
were  deemed  to  be  exercised  to  the extent presently exercisable, and the
shares  of  Common  Stock  issuable  upon  such  exercise  were  deemed  to be
outstanding.

{7/}
Includes 25,000 shares of Common Stock issuable to Hughes upon the exercise of
certain  warrants  previously  issued  by  the  Issuer.    These  Warrants are
exercisable through January 19, 2001 at an exercise price of $.01 per share.

{8/}
Consists  of  2,437,500  shares of Common Stock issuable to Hughes Electronics
upon the exercise of a warrant that Hughes Electronics received as part of the
consideration  for  a  guaranty  that it provided in connection with long-term
bank  financing  for  the Issuer ("the Hughes Electronics Warrant").  Like the
Warrant  received  by  Singapore  Telecom  in  connection  with  the long-term
financing, the Hughes Electronics Warrant is only exercisable in full upon the
fulfillment of certain conditions tied to the Issuer's ability to borrow fully
under  the  long-term loan agreements.  If such conditions are met, the Hughes
Electronics  Warrant  is ultimately exercisable for 3,750,000 shares of Common
Stock.  The Hughes Electronics Warrant is exercisable through June 28, 2001 at
an initial exercise price of $24 per share of Common Stock.

{9/}
Includes  649,347  shares  of Common Stock issuable to Investments and 230,932
shares  of  Common  Stock  issuable  to  Satellite  Communications Investments
Corporation,  respectively,  upon  the exercise of certain warrants previously
issued  by  the  Issuer.   These warrants are exercisable through December 20,
1998 at an exercise price of $21 per share of Common Stock.


<PAGE>
                                                                           10

(b)        Singapore Telecom has sole power to vote or to direct the vote, and
sole  power  to  dispose or to direct the disposition of, the shares of Common
Stock  of  the  Issuer  beneficially owned by it, subject to the effect of the
agreements  referred  to  in  Item  6.    By  reason of its ownership stake in
Singapore Telecom, Temasek may be deemed to have the power to direct the vote,
or  to  direct  the  disposition  of, the shares of Common Stock of the Issuer
beneficially  owned  by  Singapore  Telecom,  subject  to  the  effect  of the
agreements referred to in Item 6.

          To  the best knowledge of the Reporting Persons, each of the persons
listed  in Schedule I or II has sole power to vote and to direct the vote, and
sole  power  to dispose and direct the disposition of, the Common Stock of the
Issuer beneficially owned by such person.

(c)        As noted under Item 3 above, on July 1, 1996, upon the closing of a
set of agreements providing long-term bank financing for the Issuer, Singapore
Telecom  received  the  Warrant from the Issuer, which entitles it to purchase
625,000 shares of Common Stock at an initial exercise price of $24 per share. 
The  Warrant was received as part of the consideration for Singapore Telecom's
guaranty of up to $25 million in principal amount of such long-term financing.
 The  number  of shares of Common Stock for which the Warrant may be exercised
is limited to the extent that certain financial performance tests restrict the
Issuer's  ability  to borrow fully under the long-term loan agreements.  As of
July  1,  1996,  the  Warrant is exercisable for only 406,250 shares of Common
Stock.

          To  the best knowledge of the Reporting Persons, none of the persons
listed in Schedule I or II has sold or purchased shares of Common Stock during
the  past  sixty  days.

          As noted under Item 5(a) above, on July 1, 1996, upon the closing of
a  set of agreements providing long-term bank financing for the Issuer, Hughes
Electronics  received  the  Hughes  Electronics Warrant from the Issuer, which
entitles  it  to  purchase  3,750,000  shares  of  Common  Stock at an initial
exercise  price of $24 per share.  The Hughes Electronics Warrant was received
as  part  of  the consideration for Hughes Electronics' guaranty of up to $150
million in principal amount of such long-term financing.  The number of shares
of  Common  Stock for which the Hughes Electronics Warrant may be exercised is
limited  to  the  extent that certain financial performance tests restrict the
Issuer's  ability  to borrow fully under the long-term loan

<PAGE>
                                                                             11

agreements.  As of July 1, 1996, the Hughes Electronics Warrant is exercisable
for only 2,437,500 shares of Common Stock.

          The  Reporting  persons  are  not aware of transactions in shares of
Common  Stock  that  were  effectuated by the AT&T Entities during the past 60
days.

(d)     The Reporting Persons do not know of any other person having the right
to  receive  or  the  power  to  direct  the receipt of dividends from, or the
proceeds  from  the  sale  of,  the  shares  of  Common  Stock  of  the Issuer
beneficially owned by the Reporting Persons.

(e)     Not applicable.

Item 6.     Contracts, Arrangements, Understandings or Relationships
            with Respect to Securities of the Issuer

          Item  6  is  amended  and  restated only with respect to the subject
headings listed below:

                          *     *     *     *     *

Right of First Offer Agreement

          The  Issuer,  Singapore  Telecom, Hughes, the AT&T Entities, and the
Mtel  Group  are  parties  to  a Right of First Offer Agreement ("ROFA") dated
November  30,  1993,  pursuant  to  which  each  party thereto (other than the
Issuer)  (a)  granted  to  each  of the other parties (other than the Issuer),
until September 30, 2003, a right of first offer with respect to the shares of
Common  Stock, and securities exercisable or convertible into shares of Common
Stock,  now  or hereafter held by such party (excluding shares of Common Stock
acquired  by  such  party  in  the  open  market, and subject to certain other
exceptions),  and  (b)  agreed  to  terminate  the  Investment Agreement dated
January 21, 1991 among the holders of Common Stock party to the ROFA (or their
predecessors  in  interest),  pursuant  to  which the parties had granted each
other certain rights of first refusal in certain circumstances with respect to
the shares of Common Stock held by them.{10/}

          On  June 28, 1996, in connection with the execution of documentation
for  the Issuer's long-term financing, the ROFA was amended so as to limit its
application solely  to  transfers  of  shares of Common Stock (and securities
exercisable  or  convertible  into  shares  of Common Stock) between and among
Singapore Telecom, Hughes, and the AT&T Entities.

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

{10/}
Since  the  redemption  of  the  remaining Mtel Convertible Debentures and the
resulting  transfer  of  the  760,869 shares of Common Stock from Mtel L.P. to
Singapore  Telecom  causes the collective holding of shares of Common Stock by
the  Mtel  Group  to  drop  below  5%, the Mtel Group is no longer entitled to
purchase shares of Common Stock from other parties under the ROFA.


<PAGE>
                                                                           12



                          *     *     *     *     *

Mtel Partnership Agreement

          Prior  to  the conversion by Singapore Telecom of the remaining Mtel
Convertible Debentures in December 1995, Mtel Corp., Mtel Corp. Affiliate, and
Singapore  Telecom  were  parties  to  the  Mtel  Partnership Agreement.  From
November  18,  1992 (when Mtel L.P. was restructured) through December 8, 1995
(when  Singapore  Telecom redeemed the remaining Mtel Convertible Debentures),
Mtel  Corp. was the general partner of Mtel L.P., and Mtel Corp. Affiliate was
the sole limited partner.  Upon conversion of the Mtel Convertible Debentures,
Singapore  Telecom  received  Mtel LPUs, and thus became a limited partner for
the  brief  period of time necessary for Mtel L.P. to effectuate redemption of
these  LPUs  in exchange for the 760,869 shares of Common Stock held of record
by Mtel L.P.  (Sections 3.1 and 3.2 of the Mtel Partnership Agreement)

          The Mtel Partnership Agreement required that, upon any conversion of
the  Mtel  Convertible  Debentures  by Singapore Telecom, partnership units of
Singapore  Telecom  on the one hand and Mtel Corp. and/or Mtel Corp. Affiliate
on  the  other hand were to be redeemed by Mtel L.P. on a pro rata basis.  The
Mtel  Partnership Agreement also provided that the Partnership would terminate
upon  the sale or other disposition of all shares of Common Stock held by Mtel
L.P.  Thus, the conversion in full of the Mtel Convertible Debentures led to a
complete  distribution  of all shares of Common Stock held by Mtel L.P., which
in  turn caused termination of the Partnership.  (Sections 3.3 and 10.2 of the
Mtel Partnership Agreement.)

          Mtel  L.P.,  Mtel  Corp., and Singapore Telecom were also parties to
the  Amended  and Restated Pledge and Voting Agreement dated November 18, 1992
("Pledge  and  Voting  Agreement"), which was appended to the Mtel Partnership
Agreement.    Under  the  terms  of  the  Mtel Partnership Agreement, the Mtel
Convertible  Debentures, and the Pledge and Voting Agreement, the repayment of
those  Debentures was secured by the pledge to Singapore Telecom of the shares
of  Common  Stock  purchased  by  Mtel  L.P.  with  the proceeds received from
Singapore  Telecom  for  the Debentures.  Prior to the conversion by Singapore
Telecom of the remaining Mtel Convertible Debentures in December 1995, 999,545
shares  of  Common Stock held of record by Mtel L.P. were pledged to Singapore
Telecom.   Pursuant to the Pledge and Voting Agreement, upon conversion of the
remaining Mtel Convertible Debentures, Singapore Telecom released its security
interest  in  these  pledged  shares of Common Stock. (Section 3.5 of the Mtel
Partnership  Agreement;  Section  8  of  the  Mtel Convertible Debentures; and
Sections 1.1, 1.2 and 4.4 of the Pledge and Voting Agreement)

          Under  the  Pledge  and  Voting  Agreement,  Singapore Telecom, Mtel
Corp.,  and  Mtel L.P. had also agreed to cooperate in certain matters related
to  (a)  the election of directors to the Issuer's board of directors and (b)
the  appointment of directors to the executive committee of the Issuer's board
of  directors.  These provisions of the Pledge and Voting Agreement terminated
upon  the conversion of the remaining Mtel Convertible Debentures by Singapore
Telecom. (Article 5 of the Pledge and Voting Agreement)

<PAGE>
                                                                           13

Guaranty Issuance Agreement

          Singapore  Telecom, Hughes Electronics, Baron Capital Partners, L.P.
(a  stockholder  of  the  Issuer)  ("Baron,"  and  collectively with Singapore
Telecom  and  Hughes  Electronics,  the  "Guarantors"),  the  Issuer, and AMSC
Subsidiary  Corporation (a subsidiary of the Issuer) ("Issuer Subsidiary") are
parties  to the Guaranty Issuance Agreement dated June 28, 1996.  The Guaranty
Issuance Agreement specifies the compensation to be provided by the Issuer and
the  Issuer Subsidiary to Singapore Telecom, Hughes Electronics, and Baron for
the  issuance by the Guarantors of guaranties of the obligations of the Issuer
Subsidiary under the long-term loan agreements that closed on July 1, 1996.

          Under  the Guaranty Issuance Agreement, the Issuer Subsidiary agreed
to  pay  each  Guarantor  a  fee  equal to 1.5% of the principal amount of its
respective  guaranty.    In  addition,  the  Issuer  agreed  to  issue to each
Guarantor  a  warrant  to  purchase its respective Pro Rata Share of 5,000,000
shares  of  Common  Stock  at an initial exercise price of $24 per share.  The
"Pro  Rata  Share"  of  each Guarantor is equal to the principal amount of its
guaranty divided by $200,000,000.  (Section 1)

          In  addition,  the  Issuer and the Issuer Subsidiary agreed that the
aggregate  outstanding  principal amount of the loans under the long-term loan
agreements, plus any amounts paid by the Guarantors with respect to principal,
would  not  exceed the Borrowing Limit specified in the Performance Schedule. 
The  Borrowing  Limit  is  $130,000,000 during the period July 1, 1996 through
November  15, 1996, and moves up on a quarterly basis thereafter provided that
(a)  the  Issuer Subsidiary has met certain Performance Tests specified in the
Performance  Schedule,  or (b) Guarantors having a Pro Rata Share greater than
50%  have  waived  compliance  with  the  Performance  Tests  and consented to
increased borrowings by the Issuer Subsidiary.  (Section 3)

          The  Guaranty  Issuance  Agreement  also  contains  a  limited
intercreditor  arrangement  among  the Guarantors.  If any Guarantor makes any
payment  under  its  guaranty  or  acquires any notes or obligations under the
long-term  loan  agreements,  thereafter  all decisions to act or refrain from
acting  with  respect  to the enforcement of such notes or obligations against
the Issuer Subsidiary or the Issuer (including enforcement with respect to any
collateral  security  therefor) must be approved by Guarantors having Pro Rata
Shares  equal  to  at  least  80%  of  the  outstanding obligations so paid or
purchased.    In  addition,  if any Guarantor does not make a required payment
under  its guaranty, and such payment is made by any other Guarantor, then the
defaulting  Guarantor  shall  be  liable to reimburse the paying Guarantor for
such  payment  on  demand, and any amounts which would otherwise be payable to
the  defaulting  Guarantor  by  the  Issuer  Subsidiary  or the Issuer or with
respect  to  any  collateral shall first be paid to the paying Guarantor until
such payment has been fully reimbursed.  (Section 13)

The Warrant and the Registration Rights Agreement

          Pursuant to the terms of the Guaranty Issuance Agreement, the Issuer
issued  to  Singapore  Telecom  the  Warrant dated June 28, 1996.  The Warrant
entitles

<PAGE>
                                                                             14

Singapore  Telecom  to  purchase  from  the Issuer 625,000 shares of
Common Stock (the "Warrant Share Amount") at a purchase price of $24 per share
(the  "Exercise  Price").    The  Warrant  is  exercisable as of July 1, 1996,
subject  to certain restrictions, and expires on June 28, 2001.  (Section 1 of
the Warrant)

          The  exercise  of  the Warrant is restricted where (a) such exercise
would  cause  the  Issuer's  Alien Ownership Percentage to exceed the Accepted
Alien  Ownership  Percentage Limitation (which is derived from alien ownership
restrictions  under  Section  310(b)  of  the Communications Act), or (b) such
exercise  would  require the Issuer to issue Common Stock without first having
the  stockholder  approval  necessary under Rule 4460(i)(1)(D) of the National
Association  of  Securities Dealers, Inc.  Under specified circumstances where
exercise  of  the  Warrant  is prevented in whole or in part for either of the
foregoing reasons, the Issuer is required to provide the holder of the Warrant
with  a  payment  of  funds in lieu of the shares of Common Stock that are not
issuable to such holder.  (Sections 3 and 4 of the Warrant)

          The  Warrant Share Amount and the Exercise Amount are to be adjusted
under  certain  conditions,  including stock splits and asset distributions to
holders of Common Stock.  (Section 10 of the Warrant)

          In  addition  to  the  restrictions  upon  exercise  of  the Warrant
described  above,  the  number of shares of Common Stock for which the Warrant
may  be  exercised is limited to the extent that certain financial performance
tests  restrict  the Issuer's ability to borrow fully under the long-term loan
agreements.    Specifically,  the Warrant provides that it can be exercised at
any given time only for the number of shares of Common Stock which is equal to
the  applicable Warrant Share Amount as in effect from time to time, minus the
Warrant  Share  Amount multiplied by a fraction, the numerator of which is the
amount  which, due solely to the applicable Borrowing Limit (as defined in the
Guaranty  Issuance  Agreement) in effect at such time, is not available to the
Issuer  Subsidiary under the long-term loan agreements, and the denominator of
which is $200,000,000.  (Section 15 of the Warrant)

          The  Warrant  provides that the holder of the Warrant is entitled to
certain registration rights under the Registration Rights Agreement dated June
28,  1996 with respect to the shares of Common Stock for which the Warrant may
be exercised (the "Warrant Shares").  (Section 16 of the Warrant)

          Singapore  Telecom,  Hughes  Electronics,  Baron, and the Issuer are
parties  to  the  Registration  Rights  Agreement  dated  June  28, 1996.  The
Agreement  provides  a  holder  of  the Warrant or Warrant Shares with certain
demand  and  piggyback  registration rights.  The same registration rights are
provided  to the holders of the warrants issued to the other Guarantors (i.e.,
Hughes Electronics and Baron).

<PAGE>
                                                                           15



Item 7.     Material to be Filed as Exhibits

Exhibit I -- Joint Filing Agreement dated July 15, 1996

Exhibit  II  -- Amended and Restated Stockholders' Agreement dated December 1,
1993

Exhibit III -- Right of First Offer Agreement dated November 30, 1993

Exhibit IV -- Letter Agreement dated October 11, 1993

Exhibit V -- Principal Stockholder Holdback and Waiver Agreement dated October
20, 1993

Exhibit VI -- Amended and Restated Limited Partnership Agreement of Mtel Space
Technologies, L.P. dated November 18, 1992

Exhibit  VII  --  Amendment No. 1 to Right of First Offer Agreement dated June
28, 1996

Exhibit VIII -- Guaranty Issuance Agreement dated June 28, 1996

Exhibit IX -- Warrant dated June 28, 1996

Exhibit X -- Registration Rights Agreement dated June 28, 1996



<PAGE>
                                                                           16
Signatures


          After  reasonable  inquiry  and  to  the  best  of its knowledge and
belief,  the  undersigned  certifies  that  the  information set forth in this
statement is true, complete and correct.

                         SINGAPORE TELECOMMUNICATIONS LTD.



                         By:/s/ Chia Choon Wei
                            ___________________________
                            Name:     Dr. Chia Choon Wei
                            Title:    Vice President

Dated: July 15, 1996


                         TEMASEK HOLDINGS (PRIVATE) LTD.



                         By:/s/ Janet Seow
                            ____________________________
                            Name:     Janet Seow
                            Title:    Company Secretary

Dated: July 15, 1996

<PAGE>
                                                                           17
                                EXHIBIT INDEX


      Exhibit
        No.


Exhibit I        Joint Filing Agreement dated July 15, 1996

Exhibit II       Amended and Restated Stockholders' Agreement dated December 1,
                 1993

Exhibit III      Right of First Offer Agreement dated November 30, 1993

Exhibit IV       Letter Agreement dated October 11, 1993

Exhibit V        Principal  Stockholder Holdback and Waiver Agreement dated
                  October 20, 1993

Exhibit VI       Amended and Restated Limited Partnership Agreement of Mtel
                  Space Technologies, L.P. dated November 18, 1992

Exhibit VII      Amendment No. 1 to Right of First Offer Agreement dated June
                 28, 1996

Exhibit VIII      Guaranty Issuance Agreement dated June 28, 1996

Exhibit IX        Warrant dated June 28, 1996

Exhibit X         Registration Rights Agreement dated June 28, 1996


                               SCHEDULES I & II


<TABLE>
<CAPTION>
                                               SCHEDULE I


                                  SINGAPORE TELECOMMUNICATIONS LIMITED
                                      DIRECTORS & EXECUTIVE OFFICERS



                                                                    Present Principal
Name                          Position      Business Address      Occupation/Employment      Citizenship
- ------------------------  ----------------  -----------------  ----------------------------  -----------
<S>                       <C>               <C>                <C>                           <C>

Mr. Koh Boon Hwee         Board Member      Singapore Telecom  Executive Chairman            Singapore
                          Chairman          31 Exeter Road     Wuthelam Holdings Pte Ltd.
                                            Comcentre          298 Tiong Bahru Road
                                            Singapore 239732   #08-00 Tiong Bahru Plaza
                                                               Singapore 168730


Mr. Wong Hung Khim        Board Member      Singapore Telecom  Chairman                      Singapore
                          Deputy Chairman   31 Exeter Road     Singapore Bus Service (1978)
                                            Comcentre             Ltd.
                                            Singapore 239732   205 Braddell Road
                                                               Singapore 579701


BG Lee Hsien Yang         Board Member      Singapore Telecom  President & CEO               Singapore
                          President & CEO   31 Exeter Road     Singapore Telecom
                                            Comcentre          31 Exeter Road
                                            Singapore 239732   Comcentre
                                                               Singapore 239732


Dr. Hong Hai              Board Member      Singapore Telecom  President & CEO               Singapore
                                            31 Exeter Road     Haw Par Brothers
                                            Comcentre          International Ltd.
                                            Singapore 239732   180 Clemenceau Avenue
                                                               #08-00 Haw Par Glass Tower
                                                               Singapore 239722

<PAGE>
                                                                                                      2

                                                               Present Principal
Name                      Position          Business Address   Occupation/Employment         Citizenship
- ------------------------  ----------------  -----------------  ----------------------------  -----------

Mr. Liew Heng San         Board Member      Singapore Telecom  Deputy Secretary              Singapore
                                            31 Exeter Road        (Communications)
                                            Comcentre          Ministry of Communications
                                            Singapore 239732   #39-00 PSA Building
                                                               460 Alexandra Road
                                                               Singapore 119963


Mr. Lim Ho Kee            Board Member      Singapore Telecom  Executive Vice President      Singapore
                                            31 Exeter Road       & CEO
                                            Comcentre          (East Asia)
                                            Singapore 239732   Union Bank of Switzerland
                                                               80 Raffles Place
                                                               #36-00 UOB Plaza 1
                                                               Singapore 048624


Mr. Quek Poh Huat         Board Member      Singapore Telecom  President                     Singapore
                                            31 Exeter Road     Temasek Holdings Pte Ltd.
                                            Comcentre          8 Shenton Way
                                            Singapore 239732   #38-03 Treasury Building
                                                               Singapore 068811

Mr. Quek Tong Boon        Board Member      Singapore Telecom  Director                      Singapore
                                            31 Exeter Road     Defence Materiels
                                            Comcentre          Organization
                                            Singapore 239732   Ministry of Defence
                                                               18th Storey, Tower A
                                                               Defence Technology Towers
                                                               Depot Road
                                                               Singapore 109676

<PAGE>
                                                                                                  3

                                                               Present Principal
Name                      Position          Business Address   Occupation/Employment         Citizenship
- ------------------------  ----------------  -----------------  ----------------------------  -----------

Mr. Keith Tay Ah Kee      Board Member      Singapore Telecom  Asia Quest Associates         Singapore
                                            31 Exeter Road        Pte Ltd.
                                            Comcentre          30 Robinson Road
                                            Singapore 239732   #03-02A Robinson Towers
                                                               Singapore 048546


Mrs. Yu-Foo Yee Shoon     Board Member      Singapore Telecom  Assistant Secretary           Singapore
                                            31 Exeter Road     General
                                            Comcentre          National Trades Union
                                            Singapore 239732   Congress
                                                               Trade Union House
                                                               Shenton Way
                                                               Singapore 068810


Mr. Lim Toon              Executive Vice    Singapore Telecom  Executive Vice President      Singapore
                          President         31 Exeter Road     (International Network)
                            (International  Comcentre          31 Exeter Road
                          Network)          Singapore 239732   Comcentre
                                                               Singapore 239732


Mr. Raphael Leong         Executive Vice    Singapore Telecom  Executive Vice President      Singapore
Sai Mooi                  President         31 Exeter Road      (Local Services)
                          (Local Services)  Comcentre          Singapore Telecom
                                            Singapore 239732   31 Exeter Road
                                                               Comcentre
                                                               Singapore 239732


<PAGE>
                                                                                                    4


                                                               Present Principal
Name                      Position          Business Address   Occupation/Employment         Citizenship
- ------------------------  ----------------  -----------------  ----------------------------  -----------
<S>                       <C>               <C>                <C>                           <C>

Ms. Chua Sock Koong       Senior Vice       Singapore Telecom  Senior Vice President         Singapore
                          President         31 Exeter Road     (Corporate Affairs
                          (Corporate        Comcentre            & Finance)
                          Affairs           Singapore 239732   Singapore Telecom
                          & Finance)                           31 Exeter Road
                                                               Comcentre
                                                               Singapore 239732

</TABLE>




<PAGE>
                                                                              

<TABLE>
<CAPTION>
                                                                                                     5         

                                            SCHEDULE II

                                 TEMASEK HOLDINGS (PRIVATE) LIMITED
                                    DIRECTORS & EXECUTIVE OFFICERS





                                                                 Present Principal
Name                    Position        Business Address       Occupation/Employment     Citizenship
- -------------------  ---------------  --------------------  ---------------------------  -----------
<S>                  <C>              <C>                   <C>                          <C>

Mr. Lee Ek Tieng     Board Chairman   Temasek Holdings      Managing Director, Monetary  Singapore
                                      Pte Ltd.              Authority of Singapore
                                      8 Shenton Way         10 Shenton Way
                                      #38-03 Treasury Bldg  29th Floor MAS Building
                                      Singapore 068811      Singapore 079117


Mr. Ngiam Tong Dow   Deputy Board     Temasek Holdings      Permanent Secretary          Singapore
                     Chairman         Pte Ltd.              Ministry of Finance,
                     (ex-officio)     8 Shenton Way         Revenue/Budget Divisions
                                      #38-03 Treasury Bldg  8 Shenton Way #43-00
                                      Singapore 068811      Treasury Bldg
                                                            Singapore 068811


<PAGE>
                                                                                                    6

                                      Present Principal
Name                 Position         Business Address      Occupation/Employment        Citizenship
- -------------------  ---------------  --------------------  ---------------------------  -----------

Mr. Lum Choong Wah   Board Member     Temasek Holdings      Executive Chairman           Singapore
                                      Pte Ltd.              SNP Corporation Ltd.
                                      8 Shenton Way         303 Upper Serangoon Road
                                      #38-03 Treasury Bldg  Singapore 347692
                                      Singapore 068811


Dr. Andrew Chew      Board Member     Temasek Holdings      Chairman                     Singapore
Guan Khuan                            Pte Ltd.              Central Provident Fund
                                      8 Shenton Way         Board
                                      #38-03 Treasury Bldg  #41-00 CPF Building
                                      Singapore 068811      79 Robinson Road
                                                            Singapore 068897


Mr. Fock Siew Wah    Board Member     Temasek Holdings      Chairman                     Singapore
                                      Pte Ltd.              Land Transport Authority
                                      8 Shenton Way         460 Alexandra Road
                                      #38-03 Treasury Bldg  #28-00 PSA Building
                                      Singapore 068811      Singapore 119963


Mr. Lim Siong Guan   Board Member     Temasek Holdings      Permanent Secretary          Singapore
                                      Pte Ltd.              Public Service Division
                                      8 Shenton Way         8 Shenton Way
                                      #38-03 Treasury Bldg  #47-01 Treasury Building
                                      Singapore 068811      Singapore 068811


<PAGE>
                                                                                                     7

                                                            Present Principal
Name                 Position         Business Address      Occupation/Employment        Citizenship
- -------------------  ---------------  --------------------  ---------------------------  -----------

Dr. Michael Y O Fam  Board Member     Temasek Holdings      Chairman                     Singapore
                                      Pte Ltd.              Fraser & Neave Ltd.
                                      8 Shenton Way         438 Alexandra Road
                                      #38-03 Treasury Bldg  #21-00 Alexandra Point
                                      Singapore 068811      Singapore 119958




Mr. Peter Chen Min   Board Member     Temasek Holdings      Non-Executive Director       Singapore
Liang                                 Pte Ltd.              Temasek Holdings Pte Ltd.
                                      8 Shenton Way         8 Shenton Way
                                      #38-03 Treasury Bldg  #38-03 Treasury Bldg
                                      Singapore 068811      Singapore 068811


Mr. Quek Poh Huat    President        Temasek Holdings      President                    Singapore
                                      Pte Ltd.              Temasek Holdings Pte Ltd.
                                      8 Shenton Way         8 Shenton Way
                                      #38-03 Treasury Bldg  #38-03 Treasury Bldg
                                      Singapore 068811      Singapore 068811


Mr. Quek Chee Hoon   Executive Vice   Temasek Holdings      Executive Vice President     Singapore
                     President        Pte Ltd.              Temasek Holdings Pte Ltd.
                                      8 Shenton Way         8 Shenton Way
                                      #38-03 Treasury Bldg  #38-03 Treasury Building
                                      Singapore 068811      Singapore 068811


<PAGE>
                                                                                                   8

                                                            Present Principal
Name                 Position         Business Address      Occupation/Employment        Citizenship
- -------------------  ---------------  --------------------  ---------------------------  -----------

Mrs. Janet Seow      Company          Temasek Holdings      Company Secretary/           Singapore
                     Secretary/       Pte Ltd.              Vice President
                     Vice President   8 Shenton Way         Temasek Holdings Pte Ltd.
                                      #38-03 Treasury Bldg  8 Shenton Way
                                      Singapore 068811      #38-03 Treasury Bldg
                                                            Singapore 068811

</TABLE>






                                                                     EXHIBIT I



                           JOINT FILING AGREEMENT



          In  accordance  with Rule 13d-1(f) under the Securities Exchange Act
of  1934,  as  amended,  the  persons named below agree to the joint filing on
behalf  of each of them of a statement on Schedule 13D dated July 15, 1996 with
respect  to  the  Common  Stock,  par value $.01 per share, of American Mobile
Satellite  Corporation,  a  Delaware corporation.  This Joint Filing Agreement
shall  be  included  as  an Exhibit to such joint filing.  In evidence thereof
each of the undersigned, being duly authorized, hereby executes this Agreement
this 15th day of July 1996.

                         SINGAPORE TELECOMMUNICATIONS LTD.



                         By:/s/ Chia Choon Wei
                            ______________________________
                            Name:     Dr. Chia Choon Wei
                            Title:    Vice President


                         TEMASEK HOLDINGS (PRIVATE) LTD.



                         By:/s/ Janet Seow
                            _____________________________
                            Name:     Janet Seow
                            Title:    Company Secretary



<PAGE>



                        [ Exhibit II previously filed  ]



                        [ Exhibit III previously filed ]



                        [ Exhibit IV previously filed  ]



                        [ Exhibit V previously filed   ]



                        [ Exhibit VI previously filed  ]

<PAGE>






                                                                   EXHIBIT VII


              AMENDMENT NO. 1 TO RIGHT OF FIRST OFFER AGREEMENT

     This  Amendment  No.  1  (the  "Amendment")  to  the Right of First Offer
Agreement  (the  "Agreement"),  made  and  entered  into as of the 30th day of
November,  1993,  by  and  among  AMSC,  Hughes,  ST, the Investments Entities
(including  SMT),  and Mtel Group, is entered into as of the 28th day of June,
1996,  by  the  requisite  Parties  to such Amendment.  Capitalized terms used
herein  without  definition  shall  have  the  respective  meanings attributed
thereto in the Agreement.

     WHEREAS,  the  Parties  desire  to  limit  the  scope of the restrictions
contained in the Agreement;

     NOW,  THEREFORE,  in  consideration  of  the Parties' mutual promises and
agreements set forth herein and other good and valuable consideration, receipt
of which is hereby acknowledged, the Parties agree as follows:

1.          The  Parties  agree that the Agreement is amended to apply only to
Transfers  between and among Hughes, ST and Investments Entities.  The Parties
agree  that,  except  as  provided  in the foregoing sentence, the Parties may
transfer their shares without restriction under the Agreement.

2.          AMSC  further  agrees  that,  upon  request  and tender of a stock
certificate(s)  by any Party to the Agreement, AMSC will cause any restrictive
legend relating to the Agreement to be removed.

     IN  WITNESS  WHEREOF,  the Parties have executed this Amendment as of the
28th day of June, 1996.

AMERICAN MOBILE SATELLITE CORPORATION
By:     /s/  Randy Segal
   ---------------------------         
Name:        Randy Segal
Title:       Vice President


HUGHES COMMUNICATIONS SATELLITE SERVICES, INC.
By:     /s/  Harold E. McDonnell
   -----------------------------
Name:        Harold E. McDonnell
Title:       Executive Vice President

<PAGE>

SINGAPORE TELECOMMUNICATIONS LTD.
By:     /s/  Lim Toon
   -----------------------------
Name:        Lim Toon
Title:       Executive Vice President



SATELLITE COMMUNICATIONS INVESTMENTS CORPORATION
By:     /s/  Andrew A. Quartner
   ------------------------------- 
Name:        
Title:       

SPACE TECHNOLOGIES INVESTMENTS, INC.
By:     /s/  Andrew A. Quartner
   ------------------------------      
Name:        
Title:       

SATELLITE MOBIL TELEPHONE COMPANY, L.P.
Satellite Communications Investments Corporation
a General Partner
By:      /s/ Andrew A. Quartner
   -----------------------------
Name:        
Title:       

TRANSIT COMMUNICATIONS, INC.
By:          Andrew A. Quartner
   -------------------------------
Name:        
Title        


<PAGE>


                                                                EXHIBIT VIII


                                                              [Execution Copy]



                        GUARANTY ISSUANCE AGREEMENT
                           (Longer-Term Financing)





          THIS  GUARANTY  ISSUANCE  AGREEMENT (this "Agreement") dated as of
June  28,  1996  is  by  and  among HUGHES ELECTRONICS CORPORATION, a Delaware
corporation  ("Hughes"),  SINGAPORE  TELECOMMUNICATIONS  LTD.,  a  Singapore
corporation  ("SingTel"),  BARON  CAPITAL PARTNERS, L.P., a Delaware limited
partnership  ("Baron"),  AMSC SUBSIDIARY CORPORATION, a Delaware corporation
dually  incorporated  as a Virginia public service corporation ("AMSC"), and
AMERICAN  MOBILE  SATELLITE  CORPORATION,  a  Delaware  corporation  ("AMSC
Parent").


                               R E C I T A L S:

          WHEREAS,  each  of  Hughes,  SingTel  and  Baron  is,  directly  or
indirectly, a shareholder of AMSC Parent;

          WHEREAS,  AMSC  and  AMSC  Parent  have  entered  into  that certain
Securities  Purchase  Agreement  dated  as  of  January 19, 1996 (the "Bridge
Loan")  pursuant  to  which  AMSC  has issued notes (i) in the aggregate face
amount  of  $10,000,000 to Hughes Communications Satellite Services, Inc., and
(ii)  in  the  aggregate  face amount of $15,000,000 each (for an aggregate of
$30,000,000) to each of Toronto Dominion Investments, Inc. and Morgan Guaranty
Trust Company of New York;

          WHEREAS,  on  April  19, 1996 AMSC borrowed $20,000,000 from Toronto
Dominion  (Texas),  Inc.  and  Morgan  Guaranty  Trust Company of New York and
issued  its  promissory  notes  in the aggregate face amount of $20,000,000 to
evidence  such  loan  and  on  June 7, 1996 borrowed an additional $10,000,000
(collectively,  the  "Interim  Loan,"  and  the  additional $10,000,000 loan
individually, the "$10,000,000 Loan");


<PAGE>


          WHEREAS,  at  the request of AMSC and AMSC Parent, Hughes issued its
guaranty  of the Bridge Loan (the "Bridge Loan Guaranty") and of the Interim
Loan  (as  amended  or  amended  and  restated from time to time, the "Hughes
Interim  Loan  Guaranty"),  and  Hughes,  AMSC and AMSC Parent entered into a
Guaranty  Issuance  Agreement  dated  as  of April 19, 1996, as amended by the
First Amendment to Guaranty Issuance Agreement dated as of June ___, 1996 (the
"Hughes  Guaranty Issuance Agreement") providing for certain compensation to
be paid to Hughes in connection with such transactions;

          WHEREAS,  at  the  request  of Hughes, AMSC and AMSC Parent, SingTel
issued  a  guaranty  of $5,000,000 in principal amount of the $10,000,000 Loan
(the  "SingTel  Interim  Loan  Guaranty")  and SingTel, AMSC and AMSC Parent
entered  into  a  Guaranty  Issuance  Agreement  dated as of June 7, 1996 (the
"SingTel Guaranty Issuance Agreement") providing for certain compensation to
be paid to SingTel in connection with such transaction;

          WHEREAS,  AMSC  now proposes to enter into that certain $150,000,000
Credit  Agreement  providing  for up to $150,000,000 of term loans (the "Term
Loan  Agreement") and that certain $75,000,000 Credit Agreement providing for
up  to  $75,000,000 of revolving loans (the "Revolving Credit Agreement" and
together with the Term Loan Agreement, the "Credit Agreements");

          WHEREAS,  in  order  to  obtain  the  financing  under  the  Credit
Agreements,  AMSC  and AMSC Parent have requested that each of Hughes, SingTel
and  Baron  issue a guaranty of a portion of the obligations of AMSC under the
Credit  Agreements  in  substantially  the  form  attached hereto as Exhibit A
(each, a "Guaranty" and collectively, the "Guaranties"); and

          WHEREAS,  each  of  Hughes,  SingTel and Baron is willing to issue a
Guaranty  on  the  terms, and subject to the conditions, set forth herein (the
parties  which  issue  Guaranties  hereunder  are  hereafter  referred  to  as
"Guarantors").



                              A G R E E M E N T:


          NOW,  THEREFORE,  in  consideration  of  the foregoing recitals, the
parties hereto hereby agree as follows:
         
                                       2
<PAGE>

1.       Consideration for the Issuance of the Guaranties.  In consideration
of  the  issuance  of  the  respective  Guaranties, and concurrently with (and
conditioned upon) the issuance of its Guaranty, (a) AMSC Parent 
shall  issue  to  each Guarantor warrants to purchase its "Pro Rata Share" (as
defined  below)  of  5,000,000  shares of the Common Stock, par value $.01 per
share,  of  AMSC Parent at an exercise price of $24.00 per share, on the terms
described  in  the form of warrant attached hereto as Exhibit B (collectively,
the "Warrants"); and (b) AMSC shall pay to each Guarantor a fee equal to one
and  one  half  percent  (1.5%)  of the principal amount of its Guaranty.  For
purposes  of  this  Agreement,  the  "Pro  Rata Share" of a Guarantor shall be
calculated by dividing the principal amount of its Guaranty by $200,000,000.

2.     Conditions to the Issuance of the Guaranties.   (a) The obligation of
Hughes to issue its Guaranty is subject to the concurrent repayment in full of
the Bridge Loan and the Interim Loan, and the concurrent release of the Bridge
Loan Guaranty and the Hughes Interim Loan Guaranty.

     (b)    The  obligation of SingTel to issue its Guaranty is subject to the
concurrent  repayment  in  full  of  the  $10,000,000  Loan and the concurrent
release of the SingTel Interim Loan Guaranty.

     (c)    The  obligations  of  each  Guarantor are severally subject to the
following conditions:

          (1)  AMSC Parent shall have executed and delivered to the respective
Guarantor  the  Warrants  and  a  Registration  Rights  Agreement  in the form
attached hereto as Exhibit C (the "Registration Rights Agreement"), and AMSC
shall have paid to the respective party its fee, all as set forth in Paragraph
1;

          (2)    AMSC  and  AMSC  Parent  shall have received all consents and
approvals  (including  from  shareholders)  required for each of them to enter
into this Agreement, the Warrants and the Registration Rights Agreement and to
perform  its  obligations  thereunder,  and shall have delivered copies of all
such consents and approvals to each Guarantor;

          (3)    Each  Guarantor shall have approved the form and substance of
the  Credit  Agreements  and  all  documents  and  instruments  delivered  in
connection therewith, and shall have received evidence satisfactory to it that
the  liens  and  security interests of the lenders under the Credit Agreements
have been duly perfected;

          (4)    Each  Guarantor  shall have received copies, certified by the
Secretary  of each of AMSC and AMSC Parent, of resolutions duly adopted by the
Board of Directors of the applicable 

                                       3
<PAGE>

party approving the Credit Agreements and the  transactions  contemplated
thereby, this Agreement, the Warrants and the Registration Rights Agreement;

          (5)    Each  Guarantor  shall  have received the written opinions of
counsel  to  AMSC  and  AMSC Parent as to the due authorization, execution and
enforceability  of  this  Agreement,  the Warrants and the Registration Rights
Agreement, in form and substance satisfactory to each Guarantor;

          (6)  Each Other Guarantor shall have issued its Guaranty and, in the
case  of  Hughes  and  SingTel, Baron shall have obtained the letter of credit
required under the Credit Agreements; and

          (7)    The  Board of Directors of AMSC Parent shall have received an
opinion from Donaldson, Lufkin & Jenrette Securities Corporation to the effect
that  the  compensation  provided  to Guarantors pursuant to this Agreement is
fair to AMSC and AMSC Parent from a financial point of view.

3.     Limitations on Amounts of Guaranties.

     AMSC  and  AMSC  Parent have delivered to Guarantors AMSC's business plan
for  the next three fiscal years, including its projected borrowing needs (the
"Plan"),  which  has  formed  the  basis  for the agreement of Guarantors to
deliver  their  respective  Guaranties.  In consideration of the agreements of
Guarantors  to issue such Guaranties to support the extensions of credit under
the  Credit  Agreements,  AMSC agrees that the outstanding principal amount of
the  loans which are guaranteed (such outstanding amount and any payments made
by  Guarantors  with  respect  to  principal  under  the Credit Agreement, the
"Guaranteed  Amount")  shall  be  subject  to  its ability to meet certain
quarterly performance tests based on such Plan (the "Performance Tests"), as
set  forth  on  the  schedule  attached hereto as Exhibit D (the "Performance
Schedule").    Within  45 days after the end of each fiscal quarter beginning
with  the  third  quarter  of  1996,  AMSC  shall  deliver to each Guarantor a
compliance  certificate,  duly  executed  by  its  chief  financial  officer,
certifying  as  to  AMSC's  compliance with each of the four Performance Tests
specified  for such fiscal quarter on the Performance Schedule, and showing in
detail  the  calculation  of  such  compliance.    Such  certificate  shall be
accompanied  by the unaudited consolidated and consolidating balance sheets of
AMSC  and  AMSC  Parent  as  of  the  end  of  such  quarter  and  the related
consolidated  and consolidating statements of income, stockholders' equity and
cash flows, and certified by the chief financial officer as fairly presenting,
in  all  material  respects,  in accordance with generally accepted accounting
principles  (except  for  the  absence  of footnote disclosure), the financial
position and the results of operations of AMSC and AMSC Parent.

                                       4
<PAGE>

     AMSC  and  AMSC  Parent  agree  that  the aggregate outstanding principal
amount  of  the  loans  under  the  Credit Agreements plus any amounts paid by
Guarantors  with  respect  to principal shall not exceed the Guaranteed Amount
and  the  Guaranteed Amount during each applicable period shall not exceed the
"Borrowing  Limit" specified in the Performance Schedule.  If as of the end of
any  fiscal  quarter AMSC has met each of the four Performance Tests specified
for  such  fiscal  quarter on the Performance Schedule, on the forty-sixth day
after  the end of the fiscal quarter the Guaranteed Amount shall automatically
increase  to  the

 "Borrowing Limit" on such Performance Schedule for the next
period  (each, an "Increased Level").  If AMSC has failed to meet any of the
four  Performance  Tests specified on the Performance Schedule for that fiscal
quarter, the Borrowing Limit shall remain at its then current level, and shall
not increase to the next Increased Level; provided, however, that Guarantors
having  Pro  Rata  Shares  greater than 50% ("Requisite Guarantors") may, by
written notice delivered to AMSC, waive compliance with such Performance Tests
and  consent  to borrowings by AMSC which would increase the Guaranteed Amount
up  to  the  "Borrowing  Limit"  specified  in  such waiver.  A waiver granted
hereunder  shall  be  effective only as to the compliance with the Performance
Tests  for  the  specific  period and shall not obligate Guarantors to grant a
waiver  for any subsequent period or consent to any additional increase in the
applicable Borrowing Limit.

     If AMSC has failed to meet any of the four Performance Tests specified in
the  Performance  Schedule  for  any  fiscal quarter, and compliance with such
tests  has not been waived by Requisite Guarantors, or if any borrowing causes
or  would  cause the Guaranteed Amount to exceed the then applicable Borrowing
Limit, then Requisite Guarantors may, by a written notice delivered to AMSC (a
"Guarantor's  Notice"),  decline  to increase the Guaranteed Amount to cover
any  increased borrowings.  Under the terms of the Guaranties, Guarantors will
be  required  to  purchase  the  outstanding  notes  upon  the occurrence of a
"Guarantor  Event"  under the Credit Agreements, and the commitments to extend
further  financing  under  the Credit Agreements will terminate.  In addition,
the  provisions  of  Section  15  of  the  Warrants concerning cancellation of
warrants will be applicable.

     Under  the terms of the Credit Agreements, at the time of each borrowing,
AMSC  will be required to certify that it is in compliance with the provisions
of  this  Agreement.    AMSC  or AMSC Parent can so certify if the outstanding
amount of the loans after such borrowing will be less than the then applicable
"Borrowing  Limit"  or  if, and to the extent that, Requisite Guarantors shall
have  modified  such  Borrowing  Limit or waived AMSC's noncompliance with the
Performance  Tests  set  forth on the Performance Schedule.  At the request of
AMSC  and  AMSC  Parent, any "Borrowing Limit" as specified in the Performance
Schedule  or  any  of  the Performance Tests specified thereon may be modified
with  the  written  consent  of Requisite Guarantors.  If Requisite Guarantors
propose  to  increase  the  applicable  "Borrowing Limit" for any period to an
amount  in  excess of that set forth on the Performance Schedule (except as to
the  adjustments  provided  on  such  schedule  with respect to the

                                       5
<PAGE>

receipt of insurance  proceeds),  such  proposal  shall  be  discussed  with
the  other Guarantors prior to granting such consent.

     Any  action  by  Requisite  Guarantors  in accordance with this Section 3
shall  bind  all Guarantors.  Any notice delivered under this Section shall be
delivered  to  all  Guarantors,  but failure of all Guarantors to receive such
notice shall not affect the validity of such notice.

     Nothing in this Section shall limit the enforceability by the "Guaranteed
Parties" of any Guaranty in accordance with its terms.

4.         Amendments, Etc.  No amendment or waiver of any provision of this
Agreement  shall in any event be effective unless the same shall be in writing
and  with  respect  to its enforcement against any party, signed by such party
except  as  specifically  provided  in  Section  3  with respect to actions by
Requisite Guarantors.

5.          No Waiver; Remedies.  No failure on the part of any Guarantor to
exercise,  and no delay in it's exercise of, any right hereunder shall operate
as  a  waiver  thereof;  nor shall any single or partial exercise of any right
hereunder  by  any Guarantor preclude any other or further exercise thereof or
the exercise of any other right by such party.  Any Guarantor may specifically
waive  any  breach of this Agreement by AMSC or AMSC Parent; provided that (x)
no  such  waiver  shall be effective or binding unless in writing, (y) no such
waiver  shall  be effective as to any Guarantor that has not provided a waiver
with  respect  to  such  breach,  and  (z)  no  such waiver shall constitute a
continuing  waiver  of  similar or other breaches.  Any party may specifically
waive  any  condition  to its own obligations hereunder, and such waiver shall
not affect the obligations of any other party.

6.        Notices, Etc.  All notices, demands, requests, consents, approvals
and  other  instruments  hereunder  shall be in writing and shall be deemed to
have  been  properly  given if given to the parties hereto at the addresses or
facsimile  number  set  forth  on  Exhibit  E hereto, or such other address or
facsimile  number  as may be notified to the other parties hereto in a written
notice.    Notices,  demands  and  requests  shall  be  effective  if given by
facsimile to the number specified in this Section when confirmation of receipt
is received; or if given by any other means, when delivered.

7.         Separability of This Agreement.  In case any term or provision of
this  Agreement  or  any application thereof to any circumstance shall, in any
circumstances  or  jurisdiction  and  to  any  extent,  be invalid, illegal or
unenforceable,  such  term  or  provision  shall  be  ineffective  as  to such
jurisdiction to the extent of such invalidity, illegality or unenforceability,
without  invalidating  or  rendering  unenforceable  any  remaining  terms and
provisions  hereof  or  the  application  of  such  term  or  provision

                                       6
<PAGE>

to circumstances  or  jurisdictions  other  than  those  as  to  which it is
held invalid, illegal or unenforceable.

8.     Further Assurances.  AMSC and AMSC Parent hereby agree to execute and
deliver  all  such  instruments and take all such action as Hughes, SingTel or
Baron  may  from  time to time reasonably request in order to fully effectuate
the purposes of this Agreement.

9.          Headings.    The  headings  contained  in this Agreement are for
convenience of reference only and shall not modify, define or limit any of the
terms or provisions hereof.

10.          GOVERNING  LAW  AND DAMAGE LIMITATION.  THIS AGREEMENT SHALL BE
GOVERNED  BY,  AND  CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW
YORK  APPLICABLE  TO  AGREEMENTS MADE AND TO BE PERFORMED ENTIRELY WITHIN SUCH
STATE.    THE  PARTIES HEREBY IRREVOCABLY WAIVE ANY RIGHT TO A JURY TRIAL WITH
RESPECT  TO  ANY  ACTION  OR  PROCEEDING  ARISING  OUT  OF OR RELATING TO THIS
AGREEMENT.   THE PARTIES AGREE THAT NO PARTY SHALL BE LIABLE HEREUNDER FOR ANY
SPECIAL,  INDIRECT,  CONSEQUENTIAL  OR  INCIDENTAL DAMAGES, INCLUDING, WITHOUT
LIMITATION, DAMAGES FOR LOST PROFITS OR BUSINESS.

11.         Representations and Warranties of AMSC and AMSC Parent.  Each of
AMSC and AMSC Parent represent and warrant to each Guarantor that:

          (a)          Each  of  AMSC  and  AMSC  Parent is a corporation duly
organized,  validly  existing  and  in  good  standing  under  the laws of the
jurisdiction  of  its incorporation, and has all requisite corporate power and
authority to enter into and perform its obligations under this Agreement.

          (b)         This Agreement has been duly authorized by all necessary
corporate  action on the part of, and has been duly executed and delivered by,
each  of  AMSC and AMSC Parent, and none of the execution and delivery hereof,
the  consummation  of  the  transactions  contemplated  hereby  (including the
issuance  of  the Warrants and the issuance of the common stock of AMSC Parent
upon  exercise  of the Warrants and the registration of such stock pursuant to
the  Registration Rights Agreement) or compliance by AMSC and AMSC Parent with
any  of the terms and provisions hereof or of the Warrants or the Registration
Rights  Agreement  (i)  requires  any  approval of stockholders (including any
consent  under  the  rules  of the National Association of Securities Dealers,
Inc.)  or approval or consent of any trustee or holders of any indebtedness or
obligations  of  AMSC  or AMSC Parent other than such approvals or consents as
have  been  obtained, (ii) contravenes any law,

                                       7
<PAGE>

judgment, governmental rule or
regulation  or order applicable to or binding on AMSC or AMSC Parent or any of
their  respective properties, the contravention of which would have a material
adverse  effect  on the financial condition of AMSC and its subsidiaries taken
as  a  whole  or  AMSC  Parent and its subsidiaries taken as a whole or on the
ability of AMSC and AMSC Parent to perform any of their obligations under this
Agreement,  the  Warrants  or  the  Registration  Rights  Agreement,  (iii)
contravenes  or results in any breach of or constitutes any default under, any
indenture,  mortgage,  chattel  mortgage,  deed  of  trust,  conditional sales
contract,  bank loan or credit agreement for borrowed money, contract or other
agreement  or  instrument  to which AMSC or AMSC Parent is a party or by which
AMSC  or  AMSC  Parent or any of their respective properties may be bound, the
contravention, breach or default of which would have a material adverse effect
on  the  financial  condition of AMSC and its subsidiaries taken as a whole or
AMSC  Parent  and  its subsidiaries taken as a whole or on the ability of AMSC
and  AMSC Parent to perform any of their obligations under this Agreement, the
Warrants  or  the  Registration  Rights  Agreement  or  (iv)  contravenes  its
corporate charter or by-laws.

          (c)      Neither the execution, delivery and performance by AMSC and
AMSC  Parent of this Agreement nor the consummation of any of the transactions
contemplated  hereby  (including the issuance of the Warrants and the issuance
of the common stock of AMSC Parent upon the exercise of any Warrants) requires
the  consent,  approval  or  authorization of, the giving of notice to, or the
registration,  recording  or filing of any document with, or the taking of any
other  action  in respect of, any governmental agency or authority, other than
any  registration  or  other  action  required  under  the Registration Rights
Agreement.

          (d)          This  Agreement  constitutes,  and the Warrants and the
Registration  Rights  Agreement will, upon execution thereof, constitute,  the
legal,  valid  and  binding  obligation  of  each  of  AMSC  and  AMSC Parent,
enforceable  against  each  of  AMSC  and AMSC Parent in accordance with their
terms,  except  as  such enforcement may be subject to bankruptcy, insolvency,
moratorium  or other similar laws affecting creditors' rights generally and to
general principles of equity.

          (e)     AMSC Parent has delivered copies of the consolidated balance
sheet  of  AMSC  Parent  and  its consolidated subsidiaries as of December 31,
1995,  and  related  statements  of  consolidated  income  and  cash  flow and
stockholder's equity for the fiscal year then ended, accompanied by the report
of  Arthur  Andersen  LLP,  independent  accountants.   Such statements fairly
present,  in  accordance  with  generally  accepted accounting principles, the
financial position of AMSC Parent and its consolidated subsidiaries as of such
date and the results of their operations and cash flows for such fiscal year.

                                       8
<PAGE>

          (f)     AMSC Parent has duly reserved shares of its Common Stock for
issuance upon exercise of the Warrants.

12.          Reimbursement Agreement.  If Hughes, SingTel or Baron makes any
payments under its Guaranty, each of AMSC and AMSC Parent agrees that it shall
be jointly and severally liable to reimburse such Guarantor for such payments,
and that such Guarantor will be fully subrogated to the extent of such payment
to  the rights and remedies (including any collateral security) of the lenders
under  the  Credit Agreements.  If Hughes, SingTel or Baron acquires any notes
evidencing  the  loans  under  either  Credit  Agreement,  or  any  of  such
obligations,  from  the  lenders, then such Guarantor shall acquire all of the
rights  and remedies (including any collateral security) of such lenders under
the applicable Credit Agreement.  Neither Hughes, SingTel nor Baron shall have
any duties to AMSC or AMSC Parent with respect to the exercise or non-exercise
of any of such rights and remedies.

13.     Intercreditor Agreements.  (a) If Hughes, SingTel or Baron makes any
payments  under its Guaranty or acquires any notes or obligations under either
Credit  Agreement, thereafter all decisions to act or refrain from acting with
respect  to  the enforcement of such notes or obligations against AMSC or AMSC
Parent  (including  enforcement  with  respect  to  any  collateral  security
therefor)  shall  be approved by Guarantors having Pro Rata Shares equal to at
least  80%  of  the  outstanding  obligations  so paid or purchased.  Prior to
taking any such action, each Guarantor shall discuss with each other Guarantor
the actions proposed to be taken.

       (b)  If  any  Guarantor  does  not  make any required payment under its
Guaranty  (a  "defaulting  Guarantor"),  and such payment is made by any other
Guarantor  (a  "funding  Guarantor"),  then  the defaulting Guarantor shall be
liable to reimburse the funding Guarantor for such payments on demand, and any
amounts  which  would otherwise be payable to the defaulting Guarantor by AMSC
or  AMSC  Parent  or with respect to any collateral shall first be paid to the
funding  Guarantor until such payment has been fully reimbursed.  For purposes
of  this Section 13, any payment made by a funding Guarantor shall be added to
the  Pro  Rata Share of the funding Guarantor and subtracted from the Pro Rata
Share  of the defaulting Guarantor.  The funding Guarantor shall be subrogated
to  the  rights  of  the  lenders  to  enforce  the Guaranty of the defaulting
Guarantor.





                           [signature page follows]

                                       9

<PAGE>



          IN  WITNESS  WHEREOF,  each  of  the  parties hereto has caused this
Agreement to be executed by its duly authorized officer.


AMSC SUBSIDIARY CORPORATION                


By:/s/ Richard J. Burnheimer
   _______________________
Name:  Richard J. Burnheimer
Title: Treasurer


AMERICAN MOBILE SATELLITE CORPORATION


By:/s/ Richard J. Burnheimer
   ______________________
Name:  Richard J. Burnheimer
Title: Treasurer


HUGHES ELECTRONICS CORPORATION


By:/s/ Charles H. Noski
   ______________________
Name:  Charles H. Noski 
Title: Senior Vice President and
       Chief Financial Officer            


SINGAPORE TELECOMMUNICATIONS LTD.
 
By:/s/ Lim Toon
   _______________________
Name:  Lim toon
Title: Executive Vice President
       (International Services)


BARON CAPITAL PARTNERS, L.P.,
a Delaware limited partnership

By: Baron Capital Management, Inc.,
a General Partner

By:/s/ Morty Schaja
   ____________________
Name:  Morty Schaja
Title: Vice President

<PAGE>


                                  EXHIBIT B


                        [Form of Warrant -- Excluded]

                       [See Exhibit IX to Schedule 13D]






                                  EXHIBIT C

             [Form of Registration Rights Agreement -- Excluded]

                       [See Exhibit X to Schedule 13D]


<PAGE>



                                  EXHIBIT D

                    American Mobile Satellite Corporation
                         Guarantee Issuance Agreement
                             Performance Schedule
                                   ($000's)

<TABLE>
<CAPTION>

<S>                  <C>             <C>          <C>         <C>         <C>       <C>
                      7/1/96         11/16/96     2/16/97     5/16/97     8/16/97   After
                     -11/15/96       -2/15/97     -5/15/97    -8/15/97    -11/15/97 11/15/97

Borrowing Limit*      130,000        155,000      170,000     180,000     190,000   200,000


                      3Q96           4Q96         1Q97        2Q97        3Q97      4Q97


Covenants

   Subscribers        12,224         19,809       27,336      35,969      45,514    55,058

   Net Revenue         2,851          6,628       10,083      13,347      17,090    21,072

   EBITDA bef.       (19,907)       (17,949)     (14,697)    (11,500)    (8,782)    (5,657)
   Capitalized Exp.

   Operating  Cash   (30,618)       (19,539)     (10,260)     (2,639)    (1,264)   (12,529)
   Flow


*        Assumes receipt of $60 million of insurance proceeds in 3Q96.  If $60
million  is  not received until 4Q96, the Borrowing Limit increases by $60M in
3Q96  to $190M availability.  When proceeds are received in 4Q96, they must be
applied to reduce debt and the Borrowing Limit is reduced to $155M.



<PAGE>
                                                                             
                                  EXHIBIT E

                               Notice Addresses

AMERICAN MOBILE SATELLITE CORPORATION
AMSC SUBSIDIARY CORPORATION
10802 Parkridge Blvd.
Reston, Virginia  22091
Attention: Chief Financial Officer
Fax: (703) 758-6142

HUGHES ELECTRONICS CORPORATION
7200 Hughes Terrace
M/S CI/A 700
Los Angeles, California  90045-0066
Attention: Treasurer
Fax: (310) 568-7834

SINGAPORE TELECOMMUNICATIONS LTD.
31 Exeter Road, Comcentre
Singapore  239732
Republic of Singapore
Attention: Dr. Chia Choon Wei
Fax: 011-65-732-0673

BARON CAPITAL PARTNERS, L.P.
a Delaware limited partnership
450 Park Avenue
Suite 2800
New York, NY  10022
Attention: Linda S. Martinson
Fax: (212) 759-7579

After August 1, 1996:
767 Fifth Avenue
24th Floor
New York, New York  10153


<PAGE>

</TABLE>




                                                                    EXHIBIT IX


THIS  SECURITY  HAS  NOT  BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED,  OR  ANY  STATE  SECURITIES  LAWS  AND MAY NOT BE TRANSFERRED OR SOLD
EXCEPT IN COMPLIANCE THEREWITH OR PURSUANT TO AN EXEMPTION THEREFROM.



                    AMERICAN MOBILE SATELLITE CORPORATION


                    WARRANT FOR THE PURCHASE OF SHARES OF
           COMMON STOCK OF AMERICAN MOBILE SATELLITE CORPORATION


NO. ___                                                    WARRANT TO PURCHASE
                                                                625,000 SHARES


          FOR  VALUE  RECEIVED,  AMERICAN  MOBILE  SATELLITE  CORPORATION,  a
Delaware  corporation  (the  "Company"),  hereby  certifies  that  SINGAPORE
TELECOMMUNICATIONS  LTD., its successor or permitted assigns (the "Holder"),
is  entitled,  subject to the provisions of this Warrant, to purchase from the
Company,  at  the  times  specified  herein,  Six Hundred Twenty Five Thousand
(625,000)  (the "Warrant Share Amount") fully paid and non-assessable shares
of  Common  Stock  of  the  Company,  par  value  $.01 per share (the "Common
Stock"),  at  a  purchase  price  per  share  equal to the Exercise Price (as
hereinafter  defined).  The  Warrant  Share  Amount and the Exercise Price are
subject to adjustment from time to time as hereinafter set forth.

               DEFINITIONS.    The  following  terms, as used herein, have the
following meanings:

          "Accepted  Alien Ownership Percentage Limitation" means 24.99% or,
in  the event of a modification of the Alien Ownership Restrictions subsequent
to  the  date  hereof,  such  percentage  limitation  upon the Company's Alien
ownership  as  may  be  in  effect  from  time  to  time  as  a result of such
modification, less 0.01%.

          "Alien"  means any alien or a representative thereof, or a foreign
government  or  a  representative  thereof,  or  a corporation or other entity
organized under the laws of any foreign government.

          "Alien  Ownership  Percentage"  means, with respect to any Person,
the  percentage  of total ownership in such Person owned of record, as well as
the percentage of total ownership in such Person voted, by Aliens; provided,
that  if under the Alien Ownership Restrictions such Person would be deemed to
have  a percentage of total ownership owned of record or voted by Aliens other
than  the  actual  percentage  so  owned  or  voted,  then such Person's Alien
Ownership Percentage shall be such deemed percentage.

<PAGE>
          "Alien  Ownership  Restrictions"  means  Section  310(b)  of  the
Communications  Act, as modified by any interpretation, ruling or order of the
Federal  Communications Commission (or any successor agency) applicable to the
Company or any of its subsidiaries.

          "AMSC"  means  AMSC Subsidiary Corporation, a Delaware corporation
dually incorporated as a Virginia public service corporation.

          "Board of Directors" means the Board of Directors of the Company.

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

          "Communications  Act"  means  the  Communications  Act of 1934, as
amended, or any successor statute.

          "Credit  Agreements"  means,  collectively, that certain Term Loan
Agreement  providing  for  up  to  $150,000,000 of term loans and that certain
Revolving  Credit  Facility  Agreement  providing  for  up  to  $75,000,000 of
revolving loans, in each case as described in the Guaranty Issuance Agreement.

          "Current  Market Price Per Common Share" has the meaning set forth
in Section 10.D.

          "Exercise  Date"  means  the  applicable  date of exercise of this
Warrant, as indicated on the Warrant Exercise Notice delivered by the Holder.

          "Exercise  Price"  means  initially  $24.00  per Warrant Share, as
adjusted from time to time.

          "Expiration  Date" means June 28, 2001, at 5:00 p.m. New York City
time.

          "Guaranty Issuance Agreement" means that certain Guaranty Issuance
Agreement  dated  as  of  June 28, 1996 by and among the Company, AMSC, Hughes
Electronics  Corporation,  Singapore Telecommunications Ltd. and Baron Capital
Partners, L.P.

          "Holder's  Guaranty"  means  the  guaranty  by  the  Holder  of  a
specified portion (as it may be adjusted from time to time) of the obligations
of AMSC under the Credit Agreements.

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

          "Securities Act" means the Securities Act of 1933, as amended, and
the rules and regulations promulgated thereunder.

          "Warrant  Exercise  Notice"  means  the  Warrant  Exercise  Notice
forming a part hereof.

          "Warrant  Margin"  means,  on  any date, the difference of (x) the
greater  of (A) the average of the Closing Prices (as defined in Section 10.D)
on  each  of  the  20 trading days immediately preceding such date and (B) the
Closing  Price  on  the trading day two trading days prior to such date, minus
(y) the Exercise Price.

                                       2
<PAGE>

          "Warrant  Share  Amount" has the meaning set forth in the preamble
hereof.

          "Warrant Shares" means the shares of Common Stock deliverable upon
exercise of this Warrant, as adjusted from time to time.


        2.       EXERCISE OF WARRANT.

           A.       Subject  to  Section  15 hereof, the Holder is entitled to
exercise  this  Warrant in whole or in part at any time, or from time to time,
to  and  including  the Expiration Date or, if such day is not a Business Day,
then  on  the  next  succeeding day that shall be a Business Day.  To exercise
this  Warrant,  the  Holder  shall  execute  and deliver to the Company at its
address set forth in Section 12 hereof a Warrant Exercise Notice substantially
in  the  form annexed hereto and shall deliver to the Company (x) this Warrant
Certificate,  including  the Warrant Exercise Subscription Form forming a part
hereof duly executed by the Holder, and (y) subject to Section 2.B, payment of
the Exercise Price then in effect for such Warrant Shares.  Upon such delivery
and  payment,  the  Holder  shall  be deemed to be the holder of record of the
Warrant  Shares  subject  to  such  exercise,  notwithstanding  that the stock
transfer  books  of  the  Company  shall  then  be closed or that certificates
representing  such  Warrant Shares shall not then be actually delivered to the
Holder.

          B.         The  Exercise Price may be paid in cash or by certified or
official  bank  check  or  bank  cashier's  check  payable to the order of the
Company  or  by  wire  transfer  of  immediately available funds to an account
designated  by  the  Company  or  by  cancellation of indebtedness owed to the
Holder  or by any combination of such methods.  In the alternative, the Holder
may  exercise  its  right to receive Warrant Shares on a net basis, such that,
without  the  exchange  of  any  funds, the Holder will receive that number of
Warrant  Shares (and such other consideration) otherwise issuable (or payable)
upon  exercise  of  this  Warrant less that number of Warrant Shares having an
aggregate  Current Market Price Per Common Share on the Exercise Date equal to
the aggregate Exercise Price that would otherwise have been paid by the Holder
for  the Warrant Shares.  The Company shall pay any and all documentary, stamp
or similar issue or transfer taxes payable in respect of the issue or delivery
of this Warrant and the issue and delivery of the Warrant Shares.

          C.        If the Holder exercises this Warrant in part, this Warrant
Certificate  shall  be  surrendered  by  the  Holder  to the Company and a new
Warrant  Certificate  of  the  same  tenor  and  for the unexercised number of
Warrant  Shares  shall be executed by the Company.  The Company shall register
the new Warrant Certificate in the name of the Holder or in such name or names
of  its  transferee(s)  pursuant  to  Section  8  hereof as may be directed in
writing by the Holder and deliver the new Warrant Certificate to the Person or
Persons entitled to receive the same.

          D.        Except  as otherwise provided in Section 3, upon surrender
of  this  Warrant Certificate in conformity with the foregoing provisions, the
Company  shall  transfer to the Holder of this Warrant Certificate appropriate
evidence  of  ownership  of  the shares of Common Stock or other securities or
property  (including any money) to which the Holder is entitled, registered or
otherwise  placed  in,  or  payable  to the order of, the name or names of the
Holder  or  its transferee(s) as may be directed in writing by the Holder, and
shall  deliver such evidence of ownership and any other securities or property
(including  any  money) to the Person or Persons entitled to receive the same,
together with an amount in cash in lieu of any fraction of a share as provided
in Section 7 below.

    3.         OWNERSHIP  LIMITATION.    If  at  any  time the exercise of any
Warrants  pursuant  to  Section  2  would  cause the Company's Alien Ownership
Percentage  to exceed the Accepted

                                       3   
<PAGE>

Alien Ownership Percentage Limitation, then in lieu of issuing shares of Common
Stock pursuant to Section 2:

       A.     the  Company  shall issue to each Holder exercising Warrants at
such  time (each an "Exercising Holder") whose Alien Ownership Percentage is
less  than  or equal to the Accepted Alien Ownership Percentage Limitation the
number  of  shares of Common Stock to which such Exercising Holder is entitled
pursuant to Section 2;



       B.      the  Company  shall issue to each Exercising Holder whose Alien
Ownership  Percentage  is greater than the Accepted Alien Ownership Percentage
Limitation  (each,  an  "Affected  Exercising Holder") a number of shares of
Common  Stock  equal  to  the quotient of (x) the product of (A) the number of
shares  of Common Stock that, immediately after giving effect to any issuances
of  Common  Stock  pursuant to the foregoing Section 3.A, could be issued to a
Person  with  a  100% Alien Ownership Percentage without causing the Company's
Alien  Ownership  Percentage to exceed the Accepted Alien Ownership Percentage
Limitation,  multiplied  by  (B) the number of shares of Common Stock to which
such  Affected  Exercising  Holder would be entitled pursuant to Section 2 but
for  the  application of this Section 3, divided by (y) the product of (A) the
aggregate  number  of  shares of Common Stock to which all Affected Exercising
Holders  would  be  entitled  pursuant to Section 2 but for the application of
this  Section  3,  multiplied  by  (B) such Affected Exercising Holder's Alien
Ownership  Percentage;  provided that in no event shall the number of shares
of  Common  Stock  issuable to any Affected Exercising Holder pursuant to this
Section 3.B exceed the number of shares of Common Stock to which such Affected
Exercising  Holder  would have been entitled pursuant to Section 2 but for the
application of this Section 3; and

        C.     the  Company  shall  deliver  by  wire  transfer of immediately
available funds to the account of each Affected Exercising Holder specified in
such  Affected Exercising Holder's Warrant Exercise Notice, an amount equal to
the product of (x) the number of shares of Common Stock to which such Affected
Exercising  Holder would have been entitled pursuant to Section 2 that are not
issuable  to such Affected Exercising Holder pursuant to the foregoing Section
3.B, multiplied by (y) the Warrant Margin on the Exercise Date.

   4.          NASD  LIMIT.   Notwithstanding the provisions of Sections 2 and
3,  in  no  event shall this Warrant be exercisable for an aggregate number of
shares of Common Stock equal to or greater than such number of shares as would
require  the  approval  of  the  Company's  stockholders  pursuant  to  Rule
4460(i)(1)(D)  of  the  National  Association of Securities Dealers, Inc. (the
"NASD  Limit") unless the Company's stockholders have, prior to any exercise
of  this  Warrant  that would require the issuance of Common Stock equal to or
greater  than  the  NASD  Limit,  approved  the  exercise  of  Warrants for an
aggregate  number  of shares of Common Stock equal to or greater than the NASD
Limit.    If,  upon  any exercise of this Warrant, shares of Common Stock that
would  otherwise  be  issuable  upon such exercise are not issuable due to the
provisions of the foregoing sentence, then in lieu of issuing shares of Common
Stock pursuant to Sections 2 or 3:

          (i)          the Company shall issue the maximum number of shares of
Common  Stock,  if  any, issuable up to the NASD Limit; provided, that if more
than one holder of Warrants is exercising Warrants at such time, such issuance
shall  be  prorated  in  proportion to the number of shares of Common Stock to
which  each  holder  of  Warrants  exercising  Warrants  at such time would be
entitled but for the provisions of this Section 4; and

                                       4
<PAGE>

          (ii)       the Company shall deliver by wire transfer of immediately
available  funds  to  the  account of each Exercising Holder specified in such
Exercising Holder's Warrant Exercise Notice, an amount equal to the product of
(x) the number of shares of Common Stock to which such Exercising Holder would
have  been  entitled  pursuant  to the foregoing Sections 2 and 3 that are not
issuable  to  such  Exercising  Holder  pursuant  to the foregoing clause (i),
multiplied by the Warrant Margin on the Exercise Date.

   5.          RESTRICTIVE  LEGEND.  Upon original issuance thereof, and until
such  time  as the same shall have been registered under the Securities Act or
sold  pursuant  to  Rule  144  promulgated  thereunder (or any similar rule or
regulation),  each Warrant Certificate and any certificates evidencing Warrant
Shares  shall  bear a legend substantially in the form of the legend set forth
on  the  first  page  hereof,  unless  in  the  opinion  of counsel reasonably
satisfactory  to  the  Company,  such  legend  is  no  longer  required by the
Securities Act.

   6.          RESERVATION  OF  SHARES.  The Company hereby agrees that at all
times it shall reserve for issuance and delivery upon exercise of this Warrant
such  number  of its authorized but unissued shares of Common Stock as will be
sufficient  to  permit  the exercise in full of this Warrant.  All such shares
shall be duly authorized and, when issued upon such exercise, shall be validly
issued,  fully  paid and non-assessable, free and clear of all liens, security
interests, charges and other encumbrances or restrictions on sale and free and
clear of all preemptive rights.

   7.          FRACTIONAL  SHARES.  No fractional shares or scrip representing
fractional  shares  shall  be  issued upon the exercise of this Warrant and in
lieu  of  delivery  of any such fractional share upon any exercise hereof, the
Company  shall  pay  to  the  Holder  an amount in cash equal to such fraction
multiplied by the Current Market Price Per Common Share on the Exercise Date.

   8.          EXCHANGE, TRANSFER OR ASSIGNMENT OF WARRANT.

               A.          The  Company  shall  from time to time register the
exchange  or  transfer  of  any  outstanding Warrant Certificates in a Warrant
register to be maintained by the Company upon surrender thereof accompanied by
a  written  instrument  or instruments of transfer in form satisfactory to the
Company,  duly  executed by the registered Holder or Holders thereof or by the
duly appointed legal representative thereof or by a duly authorized attorney. 
Each  taker  and  holder  of this Warrant Certificate by taking or holding the
same,  consents and agrees that the registered holder hereof may be treated by
the Company and all other Persons dealing with this Warrant Certificate as the
absolute  owner  hereof for any purpose and as the Person entitled to exercise
the rights represented hereby.

               B.        Prior to any proposed transfer of the Warrants or the
Warrant  Shares,  unless  such  transfer  is  made  pursuant  to  an effective
registration  statement  under  the Securities Act, the Holder will deliver to
the  Company, if so requested by the Company, an opinion of counsel reasonably
satisfactory  in  form  and  substance  to the Company, to the effect that the
Warrants  or  Warrant  Shares,  as  applicable,  may  be  sold  or  otherwise
transferred  without  registration  under  the Securities Act.  Subject to the
preceding  sentence,  the  Holder  of  this Warrant shall be entitled, without
obtaining  the consent of the Company, to assign and transfer this Warrant, at
any  time  in  whole  or from time to time in part, to any Person or Persons. 
Subject  to  the  foregoing,  upon  surrender  of this Warrant to the Company,
together  with the attached Warrant Assignment Form duly executed, the Company
shall,  without  charge,  execute and deliver a new Warrant in the name of the
assignee  or  assignees  named  in  such  instrument of assignment and, if the
Holder's entire interest is not being assigned, in the name of the Holder, and
this Warrant shall promptly be cancelled.

                                       5
<PAGE>

   9.          LOSS  OR  DESTRUCTION  OF WARRANT CERTIFICATE.  Upon receipt by
the  Company of evidence satisfactory to it (in the exercise of its reasonable
discretion)  of  the  loss,  theft,  destruction or mutilation of this Warrant
Certificate,  and  (if  requested by the Company in the case of loss, theft or
destruction)  of  reasonably  satisfactory indemnification, and upon surrender
and  cancellation of this Warrant Certificate, if mutilated, the Company shall
execute  and  deliver  a  new  Warrant  Certificate  of  like  tenor  and date
representing the right to purchase an equivalent number of Warrant Shares.

   10.          ANTI-DILUTION PROVISIONS.


               A.         In case the Company shall at any time after the date
hereof  (i)  declare a dividend or make a distribution on Common Stock payable
in  Common  Stock  or  other  shares  of  the  Company's  capital  stock, (ii)
subdivide,  split  or  reclassify  the  outstanding Common Stock into a larger
number  of  shares,  (iii)  combine or reclassify the outstanding Common Stock
into a smaller number of shares, or (iv) issue any shares of its capital stock
in  a reclassification of Common Stock (including any such reclassification in
connection  with  a  consolidation  or  merger  in  which  the  Company is the
continuing corporation), then in each such case the Warrant Share Amount shall
be  adjusted to equal the number of shares to which the holder of this Warrant
would have been entitled upon the occurrence of such event if this Warrant had
been  exercised immediately prior to such time.  Such adjustment shall be made
successively whenever any event listed above shall occur.

               B.          In case the Company shall fix a record date for the
making  of  a  distribution  to  holders  of  Common Stock (including any such
distribution  made  in  connection with a consolidation or merger in which the
Company is the continuing corporation) of evidences of indebtedness, assets or
other  property  (excluding  cash  dividends,  other  cash  distributions from
current or retained earnings or dividends payable in Common Stock for which an
adjustment  has  been made pursuant to Section 10.A), the Warrant Share Amount
to  be in effect after such record date shall be determined by multiplying the
Warrant  Share  Amount  in  effect  immediately prior to such record date by a
fraction,  the numerator of which shall be the Current Market Price Per Common
Share,  and  the  denominator  of which shall be such Current Market Price Per
Common  Share  on  such record date, less the fair market value (determined by
the  Board  of  Directors  of the Company; provided that if the Holder shall
object  to  any  such  determination,  the  Board of Directors shall retain an
independent  appraiser reasonably satisfactory to the Holder to determine such
fair market value) of the portion of the assets, other property or evidence of
indebtedness  so  to be distributed which is applicable to one share of Common
Stock.    Such  adjustments  shall be made successively whenever such a record
date  is  fixed;  and  in the event that such distribution is not so made, the
Warrant  Share  Amount  shall again be adjusted to be the Warrant Share Amount
which would then be in effect if such record date had not been fixed.

               C.     If as a result of any event or for any other reason, any
adjustment  is  made  which  increases  the  number  of shares of Common Stock
issuable  upon  conversion,  exercise  or exchange of, or in the conversion or
exercise  price or exchange ratio applicable to, any outstanding securities of
the  Company  that  are  convertible into, or exercisable or exchangeable for,
Common  Stock  of  the  Company, then a corresponding adjustment shall be made
hereunder to increase the Warrant Share Amount, but only to the extent that no
such  adjustment  has  been  made  pursuant  to Sections 10.A or B hereof with
respect to such event or for such other reason.

               D.        For the purpose of any computation under Section 3 or
Section  10.B hereof, on any determination date the "Current Market Price Per
Common  Share"  shall  be deemed to be the average (weighted by daily trading
volume) of the Closing Prices (as defined below) per share of

                                       6
<PAGE>

Common Stock for
the  20  consecutive  trading  days immediately prior to such date.  "Closing
Price"  means (1) if shares of Common Stock then are listed and traded on the
New  York  Stock  Exchange,  Inc. ("NYSE"), the closing price on such day as
reported  on  the  NYSE  Composite  Transactions Tape; (2) if shares of Common
Stock  then  are  not listed and traded on the NYSE, the closing price on such
day  as  reported  by  the principal national securities exchange on which the
shares  are  listed  and  traded;  (3)  if shares of Common Stock then are not
listed  and  traded  on  any  such securities exchange, the last reported sale
price  on  such  day  on  the  National  Market of the National Association of
Securities  Dealers,  Inc.  Automated Quotation System ("NASDAQ"); or (4) if
shares  of Common Stock then are not traded on the NASDAQ National Market, the
average  of  the  highest reported bid and lowest reported asked price on such
day  as  reported  by  NASDAQ.   If on any determination date shares of Common
Stock  are  not  quoted by any such organization, the Current Market Price Per
Common  Share  shall  be  the  fair  market  value  of  such  shares  on  such
determination date as reasonably determined by the Board of Directors.  If the
Holder  shall  object  to  any  determination by the Board of Directors of the
Current  Market  Price  Per  Common Share, the Current Market Price Per Common
Share  shall  be the fair market value per share of Common Stock as determined
by  an  independent  appraiser  retained  by  the  Company  at its expense and
reasonably  acceptable  to  the Holder.  For purposes of any computation under
this Section 10, the number of shares of Common Stock outstanding at any given
time  shall  not  include  shares  owned  or held by or for the account of the
Company.

               E.          Upon  each  adjustment  of the Warrant Share Amount
pursuant  to  this  Section  10, the Exercise Price applicable to each Warrant
outstanding  prior to the making of the adjustment in the Warrant Share Amount
shall thereafter be adjusted to reflect an adjusted Exercise Price (calculated
to the nearest tenth of a cent) obtained from the following formula:

                         E' = E x  W
                              W'

where:

          E' =     the adjusted Exercise Price per share following the
                   adjustment of the Warrant Share Amount.

          E  =     the Exercise Price prior to adjustment.

          W' =     the adjusted Warrant Share Amount.

          W  =     the Warrant Share Amount prior to adjustment.


               F.          No  adjustment  in  the Warrant Share Amount or the
Exercise  Price  shall  be  required  unless  such adjustment would require an
increase  or  decrease of at least one percent of such amount; provided that
any  adjustments  which  by reason of this Section 10.F are not required to be
made  shall  be  carried  forward  and  taken  into  account in any subsequent
adjustment.    All  calculations  under  this  Section 10 shall be made to the
nearest  one  tenth  of  a cent or to the nearest hundredth of a share, as the
case may be.

               G.          In  the  event that, at any time as a result of the
provisions  of  this  Section  10,  the holder of this Warrant upon subsequent
exercise  shall  become entitled to receive any shares of capital stock of the
Company other than Common Stock, the number of such other shares so receivable

                                       7
<PAGE>

upon  exercise  of this Warrant shall thereafter be subject to adjustment from
time  to  time in a manner and on terms as nearly equivalent as practicable to
the provisions contained herein.

               H.         Upon any adjustment pursuant to this Section 10, the
Company  shall  promptly  thereafter  (i) cause to be filed with the Company a
certificate  of  an  officer  of  the  Company setting forth the Warrant Share
Amount  and  Exercise  Price  after  such  adjustment  and  setting  forth  in
reasonable  detail  the  method  of  calculation and the facts upon which such
calculations  are  based, and (ii) cause to be given to each registered Holder
of  this Warrant Certificate at the address as set forth in Section 12 written
notice  of  such  adjustments.  Where appropriate, such notice may be given in
advance and included as a part of the notice required to be delivered pursuant
to Section 13.B.

  11.          REORGANIZATION,  CONSOLIDATION,  MERGER, OR SALE OF ASSETS.  In
case  of  any  reclassification,  redesignation,  reorganization  or
recapitalization  by  the  Company  (other than as set forth in Section 10) or
consolidation  of  the  Company with, or merger of the Company into, any other
Person,  any  merger  of  another Person into the Company (other than a merger
which  does  not  result  in  any  reclassification,  conversion,  exchange or
cancellation of outstanding shares of Common Stock) or any sale or transfer of
all  or substantially all of the assets of the Company or of the Person formed
by  such  consolidation  or  resulting from such merger or which acquires such
assets,  as  the  case  may  be, the Holder shall have the right thereafter to
exercise  this  Warrant  for the kind and amount of securities, cash and other
property receivable upon such reclassification, redesignation, reorganization,
recapitalization,  consolidation,  merger, sale or transfer by a holder of the
number  of  shares  of  Common  Stock  for  which  this  Warrant may have been
exercised  in  full immediately prior to such reclassification, redesignation,
reorganization,  recapitalization,  consolidation,  merger,  sale or transfer,
assuming  (i)  such  holder  of  Common  Stock  is not a Person with which the
Company consolidated or into which the Company merged or which merged into the
Company  or  to  which  such  sale  or  transfer  was made, as the case may be
("constituent  Person"), or an Affiliate of a constituent Person and (ii) in
the  case  of  a  consolidation,  merger,  sale  or transfer which includes an
election as to the consideration to be received by the holders, such holder of
Common  Stock  failed  to  exercise  its rights of election, as to the kind or
amount  of  securities,  cash  and  other  property  receivable  upon  such
consolidation, merger, sale or transfer (provided that if the kind or amount
of  securities,  cash  and  other property receivable upon such consolidation,
merger,  sale  or transfer is not the same for each share of Common Stock held
immediately  prior  to  such  consolidation, merger, sale or transfer by other
than a constituent Person or an Affiliate thereof and in respect of which such
rights  of  election  shall  not have been exercised ("non-electing share"),
then  for  the  purpose  of this Section 11 the kind and amount of securities,
cash  and  other  property receivable upon such consolidation, merger, sale or
transfer  by each non-electing share shall be deemed to be the kind and amount
so  receivable  per  share  by  a  plurality  of  the  non-electing  shares). 
Adjustments  for  events  subsequent  to  the  effective  date  of  such
reclassification,  redesignation,  reorganization,  recapitalization,
consolidation,  merger and sale of assets shall be as nearly equivalent as may
be  practicable  to the adjustments provided for in this Warrant.  In any such
event,  effective  provisions  shall be made in the certificate or articles of
incorporation  of  the  resulting or surviving corporation, in any contract of
sale,  conveyance,  lease or transfer, or otherwise so that the provisions set
forth  herein  for the protection of the rights of the Holder shall thereafter
continue  to  be  applicable;  and any such resulting or surviving corporation
shall  expressly  assume the obligation to deliver, upon exercise, such shares
of stock, other securities, cash and property.  The provisions of this Section
11  shall similarly apply to successive consolidations, mergers, sales, leases
or transfers.

    12.         NOTICES.  Any notice, demand or delivery authorized or required
by  this  Warrant  Certificate  shall  be in writing and shall be given to the
Holder  or  the  Company,  as  the  case may

                                       8
<PAGE>

be, at its address (or telecopier
number) set forth below, or such other address (or telecopier number) as shall
have  been  furnished  to  the  party  giving or making such notice, demand or
delivery:

          If to the Company:     American Mobile Satellite Corporation
                         10802 Parkridge Blvd.
                         Reston, VA 22091
                         Telecopy:  (703) 758-6134
                         Attention:  Randy Segal, General Counsel


          If to the Holder:      Singapore Telecommunications Ltd.
                         31 Exeter Road, Comcentre
                         Singapore  239732
                         Republic of Singapore
                         Telecopy: 011-65-732-0673
                         Attention: Dr. Chia Choon Wei

Each  such  notice,  demand  or  delivery  shall  be effective (i) if given by
telecopy,  when  such telecopy is transmitted to the telecopy number specified
herein  and  the  intended  recipient confirms the receipt of such telecopy or
(ii)  if  given  by  any  other  means, when received at the address specified
herein.

  13.          NOTICES TO WARRANT HOLDERS.

     A.               The  Company  shall provide to each Holder, at its address
and  in  the  manner  set  forth in Section 12, a notice of expiration of this
Warrant not less than 90 nor more than 120 days prior to the Expiration Date.

     B.               In the event:

         a.         the  Company  shall  authorize  the issuance to holders of
shares  of  Common  Stock  of  rights, options or warrants to subscribe for or
purchase  shares  of  Common  Stock  or  of  any  other subscription rights or
warrants; or

         b.         the Company shall authorize the distribution to holders of
shares  of  Common  Stock  of  assets,  including  cash,  evidences  of  its
indebtedness, or other securities; or

         c.         of  any  reorganization,  consolidation or merger to which
the  Company  is  a  party  and  for which approval of any shareholders of the
Company  is  required,  or of the conveyance or transfer of the properties and
assets of the Company substantially as an entirety, or of any reclassification
or  change of Common Stock issuable upon exercise of the Warrants, or a tender
offer or exchange offer for shares of Common Stock; or

          d.        of  the  voluntary or involuntary dissolution, liquidation
or winding up of the Company; or

                                       9
<PAGE>

          e.        the Company proposes to take any action that would require
an  adjustment  to  the Warrant Share Amount or the Exercise Price pursuant to
Section 10 hereof;

then  the  Company  shall  cause to be given to each registered Holder of this
Warrant  Certificate,  at  least  20  days prior to the applicable record date
hereinafter  specified,  or 20 days prior to the date of the event in the case
of  events  for which there is no record date a written notice stating (i) the
date  as  of which the holders of record of shares of Common Stock entitled to
receive  any  such  rights,  options,  warrants  or  distribution  are  to  be
determined,  or (ii) the initial expiration date set forth in any tender offer
or  exchange  offer for shares of Common Stock, or (iii) the date on which any
such  reorganization,  reclassification,  consolidation,  merger,  conveyance,
transfer,  dissolution,  liquidation  or  winding  up  is  expected  to become
effective or consummated, and the date as of which it is expected that holders
of  record of shares of Common Stock shall be entitled to exchange such shares
for  securities  or  other  property,  if  any,  deliverable  upon  such
reorganization, reclassification, consolidation, merger, conveyance, transfer,
dissolution,  liquidation  or  winding  up.    The  failure to give the notice
required  by  this  Section  13.B  or  any defect therein shall not affect the
legality  or  validity  of  any  distribution,  right,  option,  warrant,
consolidation,  merger,  conveyance,  transfer,  dissolution,  liquidation  or
winding up, or the vote upon any action.

  14.           RIGHTS  OF  THE  HOLDER.  Prior to the exercise of any Warrant,
the  Holder  shall  not,  by  virtue  hereof,  be  entitled to any rights of a
stockholder  of the Company, including, without limitation, the right to vote,
to  receive dividends or other distributions, to exercise any preemptive right
or  to  receive  any  notice  of meetings of stockholders or any notice of any
proceedings of the Company except as may be specifically provided for herein. 
Nothing contained herein shall impose any obligation on the Holder to purchase
any  securities  or  impose any liabilities on such Holder as a stockholder of
the  Company,  whether  such  obligation  or  liabilities  are asserted by the
Company or by creditors of the Company.

  15.           LIMITATION  ON EXERCISE OF WARRANT; CANCELLATION OF WARRANTS.  
Notwithstanding  anything  to the contrary in this Warrant, this Warrant shall
be  exercisable  at any given time only for the number of Warrant Shares which
is  equal  to  the  applicable  Warrant Share Amount as in effect from time to
time,  minus  the Warrant Share Amount multiplied by a fraction, the numerator
of which is the amount which, due solely to the applicable Borrowing Limit (as
defined  in  the  Guaranty  Issuance Agreement) in effect at such time, is not
available  to AMSC under the Credit Agreements and the denominator of which is
$200,000,000  (provided,  that  if  the  numerator of such fraction is zero,
there  shall  be no limitation on the exercise of this Warrant).  In the event
that  AMSC  receives a Guarantor's Notice (as defined in the Guaranty Issuance
Agreement),  the Company shall be entitled, upon written notice to the Holder,
to  cancel  a  portion  of this Warrant such that the applicable Warrant Share
Amount in effect at the time of delivery of the Guarantor's Notice shall equal
the  number  of  Warrant  Shares  determined  in accordance with the preceding
sentence.

  16.            REGISTRATION RIGHTS. The Holder of this Warrant is entitled to
certain  registration  rights with respect to the Warrant Shares issuable upon
the  exercise  thereof.    Said  registration  rights  are  set  forth  in  a
Registration  Rights  Agreement  dated  as  of June 28, 1996, by and among the
Company  and  certain  holders  of  warrants of the Company named therein (the
"Registration  Rights  Agreement").    By  acceptance  of  this  Warrant
Certificate,  the  Holder hereof agrees that upon exercise of this Warrant, in
whole  or  in  part,  such  Holder  will  be  bound by the Registration Rights
Agreement  as  a  holder  of  Registrable  Securities thereunder.  The Company
agrees  that  upon  transfer of this Warrant, in whole or in part, pursuant to
Section  8  hereof,  the transferee shall be entitled to become a party to the

                                       10
<PAGE>

Registration  Rights  Agreement if not already a party thereto.  A copy of the
Registration  Rights  Agreement  may  be  obtained  by  the Holder hereof upon
written request to the Company.

  17.           GOVERNING  LAW  AND  WAIVER  OF  JURY  TRIAL.    THIS  WARRANT
CERTIFICATE AND ALL RIGHTS ARISING HEREUNDER SHALL BE CONSTRUED AND DETERMINED
IN  ACCORDANCE  WITH  THE  INTERNAL  LAWS  OF  THE  STATE OF NEW YORK, AND THE
PERFORMANCE  THEREOF  SHALL  BE  GOVERNED AND ENFORCED IN ACCORDANCE WITH SUCH
LAWS.    THE  PARTIES  HERETO IRREVOCABLY WAIVE ANY RIGHT TO A JURY TRIAL WITH
RESPECT  TO  ANY  ACTION  OR  PROCEEDING  ARISING  OUT  OF OR RELATING TO THIS
AGREEMENT.

  18.           AMENDMENTS; WAIVERS.  Any provision of this Warrant Certificate
may  be  amended  or  waived  if,  and only if, such amendment or waiver is in
writing  and  signed,  in  the  case  of  an  amendment, by the Holder and the
Company,  or  in the case of a waiver, by the party against whom the waiver is
to be effective.  No failure or delay by either party 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.

  19.           COUNTERPARTS.   This Warrant Certificate may be executed in any
number  of  counterparts,  each of which shall be deemed to be an original and
all of which together shall constitute one and the same instrument.


                           (signature page follows)

                                       11
<PAGE>


          IN  WITNESS  WHEREOF,  the  Company  has  duly  caused  this Warrant
Certificate  to be signed by its duly authorized officer and to be dated as of
June 28, 1996.

                              AMERICAN MOBILE SATELLITE CORPORATION



                              By:/s/ Richard J. Burnheimer
                                 _______________________________
                              Name:  Richard J. Burnheimer
                              Title: Treasurer


Acknowledged and Agreed:

SINGAPORE TELECOMMUNICATIONS LTD.



By:/s/ Lim Toon
   ______________________________
Name:  Lim Toon
Title: Executive Vice President
       (International Services)

                                    S-1
<PAGE>
                           WARRANT EXERCISE NOTICE

              (To be delivered prior to exercise of the Warrant
           by execution of the Warrant Exercise Subscription Form)


To:  American Mobile Satellite Corporation
     10802 Parkridge Blvd.
     Reston, VA 22091

          The undersigned hereby notifies you of its intention to exercise the
Warrant  to  purchase  shares  of  Common  Stock, par value $.01 per share, of
American  Mobile  Satellite  Corporation.  The undersigned intends to exercise
the  Warrant  to  purchase _____________ shares (the "Shares") [at $_______ 
per  Share  (the "Exercise Price")] [pursuant to the net exercise provisions
of Section 2.B of the Warrant].  [The undersigned intends to pay the aggregate
Exercise  Price  for  the  Shares  in cash, certified or official bank or bank
cashier's  check  or  by  wire  transfer  of immediately available funds to an
account  to  designated by the Company or by cancellation of indebtedness owed
to the Holder (or a combination of such methods) as indicated below.]

          The  undersigned  hereby certifies that to the best of its knowledge
its Alien Ownership Percentage as of the date hereof is_____________________.

Date:________________,______ .


                              ---------------------------------------
                              (Signature of Owner)


                              ---------------------------------------
                              (Street Address)


                              ---------------------------------------
                              (City)          (State)     (Zip Code)




Payment:     $ ___________               cash

             $ ___________               check

             $ ___________               wire transfer

             $ ___________               cancellation of indebtedness


[Wire  Transfer  Instructions,  if  required pursuant to Section 3 or 4 of the
Warrant:______________________________________________________________________
_____________________________________________________________________________]  

<PAGE>

                      WARRANT EXERCISE SUBSCRIPTION FORM

              (To be executed only upon exercise of the Warrant
                  after delivery of Warrant Exercise Notice)


To:     American Mobile Satellite Corporation
        10802 Parkridge Blvd.
        Reston, VA 22091

          The  undersigned  irrevocably exercises the Warrant for the purchase
of                   shares (the "Shares") of Common Stock, par value $.01
per  share,  of  American  Mobile  Satellite  Corporation (the "Company") at
$_______ per Share (the "Exercise Price") and herewith makes payment of $  
                   (such  payment  being  made  in  cash  or  by certified or
official  bank  or bank cashier's check payable to the order of the Company or
by  wire transfer or by cancellation of indebtedness owed to the Holder or any
combination  of such methods) (unless the undersigned Holder is exercising the
Warrant  pursuant  to  the  net  exercise  provisions  of  Section  2.B of the
Warrant),  all  on  the  terms  and conditions specified in the within Warrant
Certificate,  surrenders  this  Warrant  Certificate  and all right, title and
interest  therein  to the Company and directs that the Shares deliverable upon
the  exercise  of  this Warrant be registered or placed in the name and at the
address  specified  below  and delivered thereto.  If said number of Shares is
less  than  all  of  the  shares  of  Common  Stock  for  which the Warrant is
exercisable,  the  undersigned  requests  that  a  new  Warrant  Certificate
representing the remaining balance of such shares be registered in the name of
the  undersigned  or  nominee  hereinafter  set  forth,  and further that such
certificate  be  delivered  to  the undersigned at the address hereinafter set
forth or to such other person or entity as is hereinafter set forth.


Date:__________________,_______ .



                              --------------------------------------
                              (Signature of Owner)


                              --------------------------------------
                              (Street Address)


                              --------------------------------------
                              (City)          (State)     (Zip Code)



<PAGE>

Securities and/or check to be issued to:

Please insert social security or identifying number:__________________________

Name:_________________________________________________________________________

Street Address:_______________________________________________________________

City, State and Zip Code:_____________________________________________________


Any  unexercised  portion  of  the  Warrant  evidenced  by  the within Warrant
Certificate to be issued to:

Please insert social security or identifying number:__________________________

Name:_________________________________________________________________________

Street Address:_______________________________________________________________

City, State and Zip Code:_____________________________________________________


<PAGE>
                          WARRANT ASSIGNMENT FORM


                                                          Dated,______,_____

          FOR VALUE RECEIVED,________________________________________________
hereby sells, assigns and transfers unto_____________________________________
____________________________________________________________(the "Assignee"),
(please type or print in block letters)


______________________________________________________________________________ 
                         (insert Assignee's address)

______________________________________________________________________________ 
          (insert Assignee's social security or taxpayer ID number)

its  right  to  purchase  up to ________ shares of Common Stock represented by
this  Warrant  and  does  hereby  irrevocably  constitute  and  appoint
_____________________  Attorney,  to  transfer  the  same  on the books of the
Company, with full power of substitution in the premises.



                                   ___________________________________ 
                                   Signature


Signature Guarantee:

<PAGE>


                                                                     EXHIBIT X
                       REGISTRATION RIGHTS AGREEMENT


          REGISTRATION  RIGHTS  AGREEMENT  dated  as  of  June  28, 1996 among
American  Mobile  Satellite  Corporation,  a  Delaware  corporation  (the
"Company"),  Hughes  Electronics  Corporation,  Singapore Telecommunications
Ltd.,  and Baron Capital Partners, L.P. (collectively, the "Guarantors") and
each other Person who executes this Agreement.


                              W I T N E S E T H

          WHEREAS,  the  Company  and  AMSC Subsidiary Corporation, a Delaware
corporation  dually  incorporated  as  a  Virginia  public service corporation
("AMSC  Subsidiary"),  and  the  Guarantors  have  entered  into  a Guaranty
Issuance  Agreement (the "Guaranty Issuance Agreement") dated as of June 28,
1996; and

          WHEREAS,  in  order  to  induce  the  Guarantors  to  enter into the
Guaranty  Issuance  Agreement  and issue the Guaranties specified therein, the
Company  has  agreed  to  provide  the  registration  rights set forth in this
Agreement;

          NOW, THEREFORE, the parties hereto agree as follows:


                                   ARTICLE

                                 DEFINITIONS

          SECTION 1.1.    Definitions  .  The following terms, as used herein,
have the following meanings:

          "Affiliate",  as  applied  to any specified Person, shall mean any
other  Person  directly  or  indirectly  controlling or controlled by or under
direct  or  indirect  common  control  with  such  specified  Person.  For the
purposes  of  this  definition,  "control",  when  used  with respect to any
Person,  means the power to direct the management and policies of such Person,
directly or indirectly, whether through the ownership of voting securities, by
contract  or  otherwise;  and  the  terms  "controlling" and "controlled" have
meanings correlative to the foregoing.

          "Board of Directors" means the Board of Directors of the Company.

          "Bridge  Shares"  means  the  shares  of  Common  Stock  issued or
issuable  upon  exercise  of  the Bridge Warrants in accordance with the terms
thereof  and  any  Common  Stock  issued as or issuable upon the conversion or
exercise or any warrant, option, right, or other security which is issued as a
dividend  or  other  distribution  with  respect  to  or in exchange for or in
replacement  of the shares of Common Stock issued or issuable upon exercise of
the Bridge Warrants.

          "Bridge  Registration  Rights  Agreement"  means  the registration
rights  agreement  dated  as  of  April  19,  1996  among the Company, Toronto
Dominion  Investments,  Inc.,  Morgan  Guaranty  Trust Company of New York and
Hughes  Communications  Satellite  Services,  Inc.  with  respect  to  the
registration of the Bridge Shares.

<PAGE>

          "Bridge  Warrants"  means  the  warrants  to purchase Common Stock
originally issued by the Company to Toronto Dominion Investments, Inc., Morgan
Guaranty  Trust  Company  of  New  York  and  Hughes  Communications Satellite
Services, Inc. on January 19, 1996.

          "Commission"  means the Securities and Exchange Commission, or any
successor agency.

          "Common  Stock"  means the common stock, par value $.01 per share,
of the Company.

          "Deferral Period" has the meaning set forth in Section 2.1.

          "Demand Registration" has the meaning set forth in Section 2.1.

          "Demand  Registration Notice" has the meaning set forth in Section
2.1.

          "Demanding Group" has the meaning set forth in Section 2.1.

          "Exchange  Act"  means  the  Securities  Exchange  Act of 1934, as
amended, and the rules and regulations promulgated thereunder.

          "Holder"  means the holder of any Warrants or Warrant Shares other
than  Warrant  Shares that are acquired in a public distribution pursuant to a
registration  statement  under  the Securities Act or pursuant to transactions
exempt  from  registration  under  the Securities Act where securities sold in
such  transaction  may  be  resold  without  subsequent registration under the
Securities Act.

          "NASD" means the National Association of Securities Dealers, Inc.

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

          "Piggy-Back  Registration"  has  the  meaning set forth in Section
2.2.

          "Registrable  Securities"  means  the  Warrant  Shares until (i) a
Registration  Statement  covering  such  Warrant  Shares  has  been  declared
effective  by  the  Commission and they have been disposed of pursuant to such
effective  Registration  Statement,  (ii) they are sold under circumstances in
which  all of the applicable conditions of Rule 144 (or any similar provisions
then  in  force)  under  the Securities Act are met or under which they may be
sold  pursuant  to  Rule  144(k)  or  (iii)  the  Company  has delivered a new
certificate  or  other  evidence  of ownership for them not bearing the legend
required  pursuant  to  the Warrants and they may be resold without subsequent
registration under the Securities Act.

          "Registration  Statement"  means any registration statement of the
Company  relating  to  a  Demand  Registration  pursuant  to  Section 2.1 or a
Piggy-Back  Registration  pursuant to Section 2.2, in each case, including the
prospectus included therein, all amendments and supplements thereto (including
post-effective  amendments)  and  all  exhibits  and  material incorporated by
reference therein.

          "Securities Act" means the Securities Act of 1933, as amended, and
the rules and regulations promulgated thereunder.

                                       2
<PAGE>

          "Selling  Holder"  means  a  Holder  who  is  selling  Registrable
Securities pursuant to a Registration Statement under the Securities Act.

          "Underwriter"  means  a  securities  dealer  who  purchases  any
Registrable  Securities  as  principal  and  not  as  part  of  such  dealer's
market-making activities.

          "Warrants"  means  the  warrants  dated  June 28, 1996 to purchase
Common Stock.

          "Warrant  Shares"  means  the  shares  of  Common  Stock issued or
issuable  upon  exercise  of the Warrants, in each case in accordance with the
terms  thereof,  and  any  Common Stock or other securities issued or issuable
upon  the  exercise  of any warrant, option, right, or other security which is
issued  as a dividend or other distribution with respect to or in exchange for
or  in  replacement  of  the  shares  of  Common Stock issued or issuable upon
exercise of the Warrants.


                                 ARTICLE II

                             REGISTRATION RIGHTS

          SECTION 2.1.  Demand Registration.

                    Right  to  Demand.    At  any time and from time to time
prior  to  June  28,  2001,  Holders of Registrable Securities representing at
least  25%  of  the  original aggregate number of Warrant Shares for which the
Warrants were exercisable, as a group (each, a "Demanding Group") may make a
written request of the Company for registration with the Commission, under and
in  accordance  with  the  provisions of the Securities Act, of all or part of
their Registrable Securities (a "Demand Registration").  Within 5 days after
receipt  of  the  request  for  a  Demand  Registration, the Company will send
written  notice  (the  "Demand  Registration  Notice")  of such registration
request  and  its intention to comply therewith to each Holder and, subject to
paragraph  (c)  below,  the  Company  will  include  in  such registration all
Registrable  Securities  of such Holders with respect to which the Company has
received  written  requests  for  inclusion  therein  within 20 days after the
Holder's  receipt  of  the Demand Registration Notice and such Holders will be
deemed  to  be  members of the Demanding Group.  All requests made pursuant to
this paragraph (a) will specify the aggregate number of Registrable Securities
requested to be registered.

          Promptly  after  receipt  of any request for registration under this
paragraph  (a),  but  in  no  event  later  than 60 days after receipt of such
request,  the  Company shall file a Registration Statement with the Commission
with  respect to the Registrable Securities included in such request and shall
use its best efforts to have such Registration Statement declared effective as
promptly  as practicable; provided, however, that the Company may postpone
the  filing  of such Registration Statement for a period of up to 90 days (the
"Deferral  Period") if (x) the Board of Directors reasonably determines that
(i)  such a filing would adversely affect any proposed financing, acquisition,
divestiture or other material transaction by the Company or (ii) such a filing
would  otherwise  represent  an  undue  hardship for the Company, and (y) such
determination  is  reflected  in  a  certificate signed by the Chief Executive
Officer  or  President  of  the Company.  The Company shall not be entitled to
request  more  than  one such deferral with respect to any Demand Registration
within any 365-day period.  If the Company does elect to defer any such Demand
Registration,  the  Holders  requesting such Demand Registration may, at their
election  by  written  notice  to  the  Company,  (i) confirm their request to
proceed  with  such  Demand  Registration  upon the expiration of the Deferral
Period  or  (ii)  withdraw their request for such Demand Registration in which
case  no  such

                                       3
<PAGE>

request  for  a  Demand  Registration  shall be deemed to have
occurred  for  purposes of Section 2.1(b) or for any other purposes under this
Agreement (and if such Deferral Period extends past June 28, 2001, the Holders
shall  nevertheless  be  entitled  to  make  subsequent  requests  for  Demand
Registration hereunder).

              (b)     Number  of Demand Registrations.  The Demanding Group(s)
shall  collectively  be  entitled  to  two  Demand Registrations hereunder.  A
Demand  Registration  shall  not be counted as a Demand Registration hereunder
(i)  until  such  Demand  Registration  has  been  declared  effective  by the
Commission  and maintained continuously effective for a period of at least 120
days  or such shorter period as will terminate when all Registrable Securities
included  therein  have  been sold in accordance with such Demand Registration
and  (ii)  unless  the  number  of  Registrable  Securities  in  such  Demand
Registration  by  the  Demand  Group  is  at least 80% of the number of shares
originally  requested  to be included by such group after giving effect to any
reductions pursuant to paragraph (c) below.

               (c)    Priority  on  Demand  Registrations.    If in any Demand
Registration  the  managing  Underwriter  or  Underwriters  thereof advise the
Company  in writing that in its or their reasonable opinion or, in the case of
a  Demand  Registration  not  being underwritten, the Company shall reasonably
determine  after  consultation  with  an investment banking firm of nationally
recognized  standing, that the number of Registrable Securities proposed to be
sold  in  such Demand Registration exceeds the number that can be sold in such
offering  or  will  adversely  affect the success of such offering (including,
without  limitation,  an  impact  on  the  selling  price  or  the  number  of
Registrable  Securities  that  any  participant  may  sell), the Company shall
include  in  such  registration  only the number of Registrable Securities, if
any, which in the opinion of such Underwriter or Underwriters, or the Company,
as  the  case  may  be,  can  be  sold without having an adverse effect on the
success  of  the  offering  and in accordance with the following priority: (i)
first,  subject  to  the  priority  rights  of  the holders of Bridge Shares
pursuant  to  the Bridge Registration Rights Agreement, Registrable Securities
requested  to  be  included in such offering by Holders in the Demanding Group
requesting  such  registration,  allocated pro rata among such Demanding Group
(based  upon  the number of Registrable Securities requested to be included in
such  Demand  Registration), (ii) second, pro rata (based upon the number of
Registrable  Securities or similar securities requested to be included in such
registration  by  such  Holders  and  other  Persons,  if any) among the other
Holders  of Registrable Securities and other Persons having similar rights who
have requested to include Registrable Securities or similar securities in such
registration pursuant to the piggy-back registration provisions of Section 2.2
or  other  registration  rights  agreements other than the Bridge Registration
Rights  Agreement,  and (iii) third, securities proposed to be issued by the
Company for its own account.

               (d)    Selection  of  Underwriters.  If any Demand Registration
is  to be in the form of an underwritten offering, the managing Underwriter or
Underwriters  that  will  administer  the  offering  shall  be selected by the
holders  of  a  majority  of the Registrable Securities to be included in such
offering; provided that such managing underwriter or underwriters must be of
recognized  national standing and reasonably satisfactory to the Company.  The
Company  shall  (together with all Holders of Registrable Securities proposing
to  distribute Registrable Securities through such underwriting) enter into an
underwriting  agreement in customary form with the Underwriter or Underwriters
selected for such underwriting in the manner set forth above.

               (e)      Withdrawal.  If any Holder of Registrable Securities
disapproves  of  the  terms of any such underwriting, such Holder may elect to
withdraw  therefrom  by  written  notice  to  the  Company  and  the  managing
Underwriter.    If  by the withdrawal of such Registrable Securities a greater
number of Registrable Securities held by other Holders may be included in such
registration  (up  to  the

                                       4
<PAGE>

maximum  of  any  limitation  imposed  by  the
Underwriters),  then  the Company shall offer to all Holders who have included
Registrable  Securities  in  the  registration the right to include additional
Registrable  Securities  in  the priority and proportions specified in Section
2.1(c).



          SECTION 2.2.  Piggy-Back Registration .

             (a) If  the  Company  proposes  to  file a registration statement
under  the  Securities  Act with respect to an offering by the Company for its
own account or for the account of any of its respective securityholders of any
class  of equity security or security convertible into or exchangeable for any
class  of  equity security (other than a registration statement on Form S-4 or
S-8  (or  any  substitute  form  that  may be adopted by the Commission), or a
registration  filed  in  connection  with  an  exchange  offer  or offering of
securities  solely  to  the  Company's  existing  securityholders  or  other
registrations  solely  in  connection  with  employee  stock  options or other
employee  benefit  plans),  then the Company shall give written notice of such
proposed  filing  to  the  Holders  of  Registrable  Securities  as  soon  as
practicable  (but  in no event less than 30 days before the anticipated filing
date),  and  such  notice shall offer such Holders the opportunity to register
such  number  of  shares  of  Registrable  Securities  as each such Holder may
request  (a  "Piggy-Back  Registration").    The  Company shall use its best
efforts  to  cause  the  managing  Underwriter  or  Underwriters of a proposed
underwritten  offering  to  permit  the Registrable Securities requested to be
included  in  a  Piggy-Back  Registration to be included on the same terms and
conditions  as  any  similar securities of the Company included therein and to
permit  the  sale  or  other  disposition  of  such  Registrable Securities in
accordance with the intended method of distribution thereof.

               No registration effected under this Section 2.2, and no failure
to  effect a registration under this Section 2.2, shall relieve the Company of
its  obligations  pursuant  to  Section  2.1,  and  no  failure  to  effect  a
registration  under  this  Section  2.2  and  complete  the  sale of shares in
connection  therewith  shall relieve the Company of any other obligation under
this Agreement (including, without limitation, the Company's obligations under
Sections 3.2 and 4.1).

             (b)    Notwithstanding anything contained herein, if the managing
Underwriter  or  Underwriters  of  an  offering  described  in  the  foregoing
paragraph  (a)  deliver  a  written  opinion to the Holders of the Registrable
Securities  proposed  to be included in such offering that (i) the size of the
offering  that  the Holders, the Company and such other Persons intend to make
or  (ii)  the  kind  of securities that the Holders, the Company and any other
Persons  intend  to  include in such offering are such that the success of the
offering  would  be  materially  and  adversely  affected  by inclusion of the
Registrable  Securities requested to be included, then subject to the priority
rights  of  the  holders  of Bridge Shares pursuant to the Bridge Registration
Rights  Agreement,  (A)  if  the  size  of  the  offering is the basis of such
Underwriter's opinion, the amount of securities to be offered for the accounts
of  Holders  and the amount of securities to be offered for the account of the
Company  shall  be  reduced  pro  rata  (based  upon the number of Registrable
Securities or other securities proposed to be included in such registration by
the  Holders  and  the Company) and the amount of securities to be offered for
the  account  of  any  other Persons (other than the holders of Bridge Shares)
shall  be  reduced  to  zero;  and  (B) if the combination of securities to be
offered  is  the  basis  of  such  Underwriter's  opinion,  (x)  the amount of
securities  to  be  offered  for  the  accounts  of  Holders and the amount of
securities  to  be offered for the account of the Company shall be reduced pro
rata  (based  upon  the  number  of Registrable Securities or other securities
proposed  to  be included in such registration by the Holders and the Company)
and  the  amount  of  securities  to  be offered for the account of such other
Persons  (other than the holders of Bridge Shares) shall be reduced to zero to
the  extent  necessary,  in  the  judgment  of  the  managing  Underwriter, to
substantially  eliminate  the adverse effect that inclusion of the Registrable
Securities requested to be included would have on such offering.

                                       5
<PAGE>

               (c)       The Holders of Registrable Securities included within
such  Piggy-Back  Registration may withdraw all or any part of the Registrable
Securities from such Piggy-Back Registration at any time (before but not after
the  effective  date  of  such  Registration Statement), by delivering written
notice of such withdrawal request to the Company.

               (d)       If the Company shall determine for any reason (x) not
to  register  or  (y)  to  delay  a  registration  which  includes Registrable
Securities  pursuant  to  this  Section 2.2, the Company may, at its election,
give  written  notice  of such determination to the Holders of the Registrable
Securities  and, thereupon (i) in the case of a determination not to register,
shall  be relieved of its obligation to register any Registrable Securities in
connection  with  such  registration  (but  not from its obligation to pay the
Registration Expenses in connection therewith), without prejudice, however, to
the  rights,  if  any,  of  any Holder or Holders of Registrable Securities to
request  that  such  registration  be  effected as a Demand Registration under
Section  2.1,  and  (ii)  in  the  case  of  a  delay in registering, shall be
permitted  to delay registering any Registrable Securities for the same period
as the delay in registering such other shares.


                                 ARTICLE III

                           REGISTRATION PROCEDURES

          SECTION 3.1. Filings; Information .  Whenever Registrable Securities
are  to be registered pursuant to Section 2.1 hereof, the Company will use its
best  efforts  to  effect  the  registration  and the sale of such Registrable
Securities  in  accordance  with the intended method of disposition thereof as
quickly as practicable, and in connection with any such request:

         (a)    The Company will as expeditiously as possible (and in any event
within  the time period specified in Section 2.1(a)) prepare and file with the
Commission  a  Registration  Statement  on any form for which the Company then
qualifies or which counsel for the Company and counsel for the Selling Holders
shall  deem  appropriate and which form shall be available for the sale of the
Registrable  Securities  to  be  registered  thereunder in accordance with the
intended  method  of  distribution  thereof,  and  if  the  offering  is  an
underwritten  offering,  shall  be  reasonably  satisfactory  to  the managing
Underwriter  or  Underwriters.  The Company will use its best efforts to cause
such  filed Registration Statement to become and remain continuously effective
in accordance with Section 2.1(b).

          (b)  The  Company  will  prior to filing a Registration Statement or
prospectus  or  any  amendment  or supplement thereto, furnish to each Selling
Holder  and each Underwriter, if any, of the Registrable Securities covered by
such  Registration Statement copies of such Registration Statement as proposed
to be filed, and thereafter furnish to such Selling Holder and Underwriter, if
any,  such number of copies of such Registration Statement, each amendment and
supplement  thereto (in each case including all exhibits thereto and documents
incorporated  by  reference  therein),  the  prospectus  included  in  such
Registration  Statement (including each preliminary prospectus) and such other
documents  as  such  Selling  Holder  or Underwriter may reasonably request in
order  to  facilitate  the  disposition of the Registrable Securities owned by
such Selling Holder.

           (c) After  the  filing  of  the Registration Statement, the Company
will  promptly notify each Selling Holder of Registrable Securities covered by
such  Registration  Statement  of

                                       6
<PAGE>

any  stop order issued or threatened by the Commission and take all reasonable
actions required to prevent the entry of such stop order or to remove it if
entered.

         (d)   The  Company  will  use  its  best  efforts  to (i) register or
qualify  the  Registrable  Securities  under such other securities or blue sky
laws  of  such  jurisdictions  in  the  United States as any Selling Holder or
managing  Underwriter  reasonably  (in light of such Selling Holder's intended
plan  of  distribution) requests and (ii) cause such Registrable Securities to
be  registered  with  or  approved by  such  other  governmental  agencies or
authorities  as  may  be necessary by virtue of the business and operations of
the  Company  and  do any and all other acts and things that may be reasonably
necessary  or advisable to enable such Selling Holder and the Underwriters, if
any, to consummate the disposition of the Registrable Securities owned by such
Selling  Holder;  provided  that  the  Company  will  not be required to (A)
qualify  generally  to  do  business  in  any  jurisdiction where it would not
otherwise  be  required  to  qualify  but  for this paragraph (d), (B) subject
itself  to taxation in any such jurisdiction or (C) consent to general service
of process in any such jurisdiction.

         (e)   The Company will immediately notify each Selling Holder, at any
time  when a prospectus relating thereto is required to be delivered under the
Securities  Act,  of the occurrence of an event requiring the preparation of a
supplement or amendment to such prospectus so that, as thereafter delivered to
the  purchasers  of  such  Registrable  Securities,  such  prospectus will not
contain  an  untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary to make the statements therein
not  misleading,  in  light  of the circumstances in which they were made, and
promptly  file  with  the Commission and make available to each Selling Holder
any such supplement or amendment.

          (f)  The  Company will enter into customary agreements (including an
underwriting  agreement  in  customary form if the offering is an underwritten
offering)  and  take such other actions as are reasonably required in order to
expedite  or  facilitate  the  disposition  of  such  Registrable  Securities,
including,  in the case of an offering pursuant to Section 2.1, cooperating in
the  marketing  efforts  of the Underwriters and the Selling Holders by, among
other  things,  making  available, as reasonably requested by the Underwriters
and  the  Selling  Holders,  senior  executive  officers  of  the  Company for
attendance  at,  and  active  participation  with  the  Underwriters  in,
informational  meetings  with  prospective  purchasers  of  the  Registrable
Securities  being offered, including meeting with groups of such purchasers or
with  individual  purchasers,  providing  information  and answering questions
about  the  Company at such meetings, and traveling to locations at reasonable
times and as reasonably selected by the Underwriters.

           (g) The  Company  will make available for inspection by any Selling
Holder,  any  Underwriter  participating  in  any disposition pursuant to such
Registration  Statement  and  any  attorney,  accountant or other professional
retained  by  any  such  Selling  Holder  or  Underwriter  (collectively,  the
"Inspectors"),  all  financial  and  other  records,  pertinent  corporate
documents  and  properties  of  the Company (collectively, the "Records") as
shall  be  reasonably necessary to enable them to exercise their due diligence
responsibility,  and  cause the Company's officers, directors and employees to
supply  all  information  reasonably requested by any Inspectors in connection
with  such  Registration  Statement.  Records which the Company determines, in
good  faith,  to  be  confidential  and  which  it notifies the Inspectors are
confidential  shall  not  be  disclosed  by  the  Inspectors  unless  (i)  the
disclosure  of such Records is necessary to avoid or correct a misstatement or
omission in such Registration Statement or (ii) the release of such Records is
ordered  pursuant  to  a  subpoena  or  other  order from a court of competent
jurisdiction.   Each 

                                       7
<PAGE>

Selling Holder of such Registrable Securities agrees that
information  obtained  by  it  as a result of such inspections shall be deemed
confidential  and  shall  not  be  used  by  it  as  the  basis for any market
transactions  in  the  securities  of the Company or its Affiliates unless and
until  such is made generally available to the public.  Each Selling Holder of
such  Registrable  Securities  further agrees that it will, upon learning that
disclosure  of  such  Records  is sought in a court of competent jurisdiction,
give notice to the Company and allow the Company, at its expense, to undertake
appropriate action to prevent disclosure of the Records deemed confidential.

       (h)     The  Company  will  furnish  to each Selling Holder and to each
Underwriter, if any, a signed counterpart, addressed to such Selling Holder or
Underwriters  of (i) an opinion or opinions of counsel to the Company and (ii)
a  comfort  letter  or  comfort  letters from the Company's independent public
accountants,  each  in  customary  form  and covering such matters of the type
customarily covered by opinions or comfort letters, as the case may be, as the
holders  of a majority of the Registrable Securities included in such offering
or the managing Underwriter therefor reasonably requests.

       (i)     If requested by the Selling Holders, the Company will provide a
CUSIP  number for all Registrable Securities not later than the effective date
of the Registration Statement covering such Registrable Securities and provide
the  Company's  transfer  agent(s)  and  registrar(s)  for  the  Registrable
Securities with printed certificates for the Registrable Securities.

       (j)     The  Company  will cooperate and assist in any filings required
to  be  made  with  the  NASD  and  in  the  performance  of any due diligence
investigation  by  any  Underwriter  (including  any  "qualified  independent
underwriter") that is required to be retained in accordance with the rules and
regulations  of  the NASD, and use its best efforts to cause such Registration
Statement  to  become  effective and approved by such governmental agencies or
authorities as may be necessary to enable the Selling Holders or Underwriters,
if any, to consummate the disposition of such Registrable Securities.

        (k)    The  Company will otherwise use its best efforts to comply with
all  applicable rules and regulations of the Commission, and make available to
its  securityholders, as soon as reasonably practicable, an earnings statement
covering  a  period  of  12  months,  beginning  within three months after the
commencement of any public offering of securities pursuant to the Registration
Statement,  which  earnings  statement shall satisfy the provisions of Section
11(a) of the Securities Act.

        (l)    The  Company  will  use  its  best  efforts  to  cause all such
Registrable  Securities  to  be  listed  on  each securities exchange on which
similar securities issued by the Company are then listed.

          The  Company  may require each Selling Holder to promptly furnish in
writing  to  the  Company  such  information regarding the distribution of the
Registrable Securities as the Company may from time to time reasonably request
and  such other information as may be legally required in connection with such
registration.

          Each Selling Holder agrees that, upon receipt of any notice from the
Company  of the happening of any event of the kind described in Section 3.1(e)
hereof,  such  Selling  Holder  will  forthwith  discontinue  disposition  of
Registrable  Securities  pursuant  to the Registration Statement covering such
Registrable  Securities  until  such Selling Holder's receipt of the copies of
the  supplemented or amended 

                                       8
<PAGE>

prospectus contemplated by Section 3.1(e) hereof,
and,  if  so  directed by the Company, such Selling Holder will deliver to the
Company  (at  the  Company's  expense)  all  copies, other than permanent file
copies then in such Selling Holder's possession, of the most recent prospectus
covering  such  Registrable Securities at the time of receipt of such notice. 
In  the event the Company shall give such notice, the Company shall extend the
period  during which such Registration Statement shall be maintained effective
(including  the  period referred to in Section 3.1(a) hereof) by the number of
days  during  the  period  from and including the date of the giving of notice
pursuant  to  Section  3.1(e)  hereof  to the date when the Company shall make
available  to  the  Selling  Holders  a  prospectus supplemented or amended to
conform with the requirements of Section 3.1(e) hereof.

          SECTION 3.2.   Expenses.    The  Company  shall pay the following
expenses  incurred in connection with any registration required hereunder (the
"Registration  Expenses"),  regardless  of  whether a Registration Statement
becomes  effective:    (i)  all  registration  and  filing fees, (ii) fees and
expenses  of compliance with securities or blue sky laws (including reasonable
fees  and  disbursements of counsel in connection with blue sky qualifications
of  the  Registrable  Securities), (iii) printing and engraving expenses, (iv)
internal  expenses of the Company (including, without limitation, all salaries
and  expenses  of  its  officers  and employees performing legal or accounting
duties),  (v) all fees and expenses incurred in connection with the listing of
the  Registrable Securities, (vi) reasonable fees and disbursements of counsel
for  the  Company  and  customary  fees and expenses for independent certified
public  accountants  retained  by  the  Company (including the expenses of any
comfort letters or costs associated with the delivery by independent certified
public  accountants  of a comfort letter or comfort letters requested pursuant
to  Section  3.1(h)  hereof),  (vii)  the  reasonable fees and expenses of any
special  experts retained by the Company in connection with such registration,
(viii)  reasonable  fees  and expenses of one counsel (who shall be reasonably
acceptable  to  the  Company)  for  the  Holders,  (ix) in connection with any
underwritten  offering  or  proposed  underwritten  offering  of  Registrable
Securities  hereunder,  the  reasonable  fees  and  disbursements  of  the
Underwriters  and  counsel  for  the  Underwriters (excluding any underwriting
discounts or commissions with respect to Registrable Securities not being sold
for  the  account  of the Company), and reasonable expenses in connection with
the  marketing  efforts of the Underwriters and the Selling Holders, including
expenses  related  to  meetings with prospective purchasers of the Registrable
Securities  and  any  travel  costs related thereto and (xi) fees and expenses
associated  with  any  NASD  filing required to be made in connection with the
registration  of  the  Registrable  Securities,  including, if applicable, the
reasonable  fees  and expenses of any "qualified independent underwriter" (and
its  counsel) that is required to be retained in accordance with the rules and
regulations of the NASD.


                                   ARTICLE IV

                       INDEMNIFICATION AND CONTRIBUTION

          SECTION 4.1.  Indemnification by the Company.  The Company agrees to
indemnify  and  hold harmless each Selling Holder, its officers, directors and
agents,  and  each Person, if any, who controls such Selling Holder within the
meaning  of Section 15 of the Securities Act or Section 20 of the Exchange Act
from and against any and all losses, claims, damages and liabilities caused by
any  untrue statement or alleged untrue statement of a material fact contained
in  any  Registration  Statement  or  prospectus  relating  to the Registrable
Securities (as amended or supplemented if the Company shall have furnished any
amendments or supplements thereto) or any preliminary prospectus, or caused by
any  omission or alleged omission to state therein a material fact required to
be  stated  therein or necessary to make the statements therein not misleading
(in  the  case of a prospectus, in light of the circumstances under which they
were  made), except insofar as such losses, claims, damages or liabilities are
caused by 

                                       9 
<PAGE>

any such untrue statement or omission or alleged untrue statement or
omission  based  upon  information furnished in writing to the Company by such
Selling  Holder  or on such Selling Holder's behalf expressly for use therein;
provided,  however, that the foregoing indemnity agreement with respect to
any  preliminary  prospectus  shall  not  inure  to the benefit of any Selling
Holder  from  whom  the  Person  asserting  any  such  loss,  claim, damage or
liability purchased the Registrable Securities if it is determined that it was
the  responsibility  of  such  Selling  Holder  to  provide such Person with a
current  copy  of the prospectus and such current copy of the prospectus would
have  cured  the defect giving rise to such loss, claim, damage or liability. 
In  connection  with  any  underwritten  offering,  the Company also agrees to
indemnify  the  Underwriters of the Registrable Securities, their officers and
directors  and each Person who controls such Underwriters on substantially the
same  basis  as that of the indemnification of the Selling Holders provided in
this Section 4.1.
  

          SECTION 4.2.  Indemnification  by  Selling  Holders.  Each Selling
Holder  agrees,  severally but not jointly, to indemnify and hold harmless the
Company,  its  officers,  directors  and  agents  and each Person, if any, who
controls the Company within the meaning of either Section 15 of the Securities
Act  or  Section  20  of  the Exchange Act to the same extent as the foregoing
indemnity  from the Company to such Selling Holder, but only with reference to
information related to such Selling Holder furnished in writing to the Company
by such Selling Holder or on such Selling Holder's behalf expressly for use in
any  Registration  Statement  or  prospectus  relating  to  the  Registrable
Securities,  or  any  amendment  or  supplement  thereto,  or  any preliminary
prospectus.  In connection with any underwritten offering, each Selling Holder
also agrees to indemnify and hold harmless the Underwriters of the Registrable
Securities,  their  officers  and  directors and each Person who controls such
Underwriters on substantially the same basis as that of the indemnification of
the  Company  provided  in this Section 4.2.  Notwithstanding anything in this
Agreement  to  the contrary, in no event shall any Selling Holder be obligated
to  provide  indemnification  hereunder  in connection with any offering in an
amount  that  exceeds  the  proceeds of such offering received by such Selling
Holder.

          SECTION 4.3.  Conduct of Indemnification Proceedings .  In case any
proceeding  (including  any  governmental  investigation)  shall be instituted
involving  any  Person in respect of which indemnity may be sought pursuant to
Section  4.1  or  4.2,  such  Person (an "Indemnified Party") shall promptly
notify the Person against whom such indemnity may be sought (an "Indemnifying
Party")  in  writing  and  the  Indemnifying  Party  shall assume the defense
thereof,  including  the employment of counsel reasonably satisfactory to such
Indemnified  Party, and shall assume the payment of all fees and expenses.  In
any  such proceeding, any Indemnified Party shall have the right to retain its
own counsel, but the fees and expenses of such counsel shall be at the expense
of  such  Indemnified  Party  unless  (i)  the  Indemnifying  Party  and  the
Indemnified  Party shall have mutually agreed to the retention of such counsel
or  (ii)  the  named  parties  to any such proceeding (including any impleaded
parties)  include  both  the  Indemnified Party and the Indemnifying Party and
representation  of both parties by the same counsel would be inappropriate due
to  actual  or  potential differing interests between them.  It is understood 
that  the  Indemnifying  Party shall not, in connection with any proceeding or
related  proceedings  in  the  same jurisdiction, be liable for the reasonable
fees  and expenses of more than one separate firm of attorneys (in addition to
any  local counsel) at any time for all such Indemnified Parties, and that all
such  fees and expenses shall be reimbursed as they are incurred.  In the case
of  any  such  separate  firm  for the Indemnified Parties, such firm shall be
designated  in  writing  by  the  Indemnified Parties.  The Indemnifying Party
shall  not be liable for any settlement of any proceeding effected without its
written  consent,  but  if   settled with such consent, or if there be a final
judgment  for  the  plaintiff, the Indemnifying Party shall indemnify and hold
harmless  such  Indemnified Parties from and against any loss or liability (to
the  extent  stated  above)  by  reason  of  such  settlement  or  judgment.  
Notwithstanding  the  foregoing  sentence, if at any time an Indemnified Party
shall  have requested an Indemnifying Party

                                       10 
<PAGE>

to reimburse the Indemnified Party
for fees and expenses of counsel as contemplated by the third sentence of this
paragraph,  the  Indemnifying  Party  agrees  that  it shall be liable for any
settlement  of any proceeding effected without its written consent if (i) such
settlement  is  entered  into more than 30 business days after receipt by such
Indemnifying  Party  of the aforesaid request and (ii) such Indemnifying Party
shall  not  have  reimbursed  the  Indemnified  Party  in accordance with such
request  prior  to  the date of such settlement.  No Indemnifying Party shall,
without  the  prior  written  consent  of  the  Indemnified  Party, effect any
settlement  of  any  pending  or threatened proceeding in respect of which any
Indemnified  Party is or could have been a party and indemnity could have been
sought hereunder by such indemnified party, unless such settlement includes an
unconditional release of such Indemnified Party from all liability arising out
of such proceeding.

          SECTION 4.4. Contribution.  If the indemnification provided for in
this  Article  4  is  unavailable  to  an  Indemnified Party in respect of any
losses,  claims,  damages  or  liabilities  referred  to  herein,  then  each
Indemnifying  Party,  in  lieu  of  indemnifying such Indemnified Party, shall
contribute to the amount paid or payable by such Indemnified Party as a result
of such losses, claims, damages or liabilities.  As between the Company on the
one  hand  and  each  Selling  Holder on the other, the amount of contribution
shall be in such proportion as is appropriate to reflect the relative fault of
the  Company  and of each Selling Holder in connection with such statements or
omissions,  as  well  as  any  other  relevant  equitable considerations.  The
relative  fault  of  the Company on the one hand and of each Selling Holder on
the other shall be determined by reference to, among other things, whether the
untrue  or  alleged  untrue  statement  of  a material fact or the omission or
alleged  omission  to state a material fact relates to information supplied by
such party, and the parties' relative intent, knowledge, access to information
and opportunity to correct or prevent such statement or omission.

          The  Company and the Selling Holders agree that it would not be just
and  equitable if contribution pursuant to this Section 4.4 were determined by
pro  rata  allocation or by any other method of allocation which does not take
account  of  the  equitable  considerations  referred  to  in  the immediately
preceding  paragraph.  The amount paid or payable by an Indemnified Party as a
result  of  the  losses,  claims,  damages  or  liabilities referred to in the
immediately  preceding  paragraph  shall  be deemed to include, subject to the
limitations  set  forth above, any legal or other expenses reasonably incurred
by  such  Indemnified  Party in connection with investigating or defending any
such  action  or  claim.    Notwithstanding  anything  to the contrary in this
Agreement,  in no event shall any Selling Holder be obligated to contribute in
connection  with  any  offering in an amount that exceeds the proceeds of such
offering  received  by  such  Selling  Holder, minus the amount of any damages
which such Selling Holder has otherwise been required to pay by reason of such
untrue or alleged untrue statement or omission or alleged omission.  No Person
guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of
the  Securities Act) shall be entitled to contribution from any Person who was
not  guilty  of  such  fraudulent  misrepresentation.    The  Selling Holders'
obligations  to  contribute  pursuant  to this Section 4.4 are several and not
joint.


                                  ARTICLE V

                                MISCELLANEOUS

          SECTION 5.1.   Participation  in  Underwritten  Registrations .  No
Person  may participate in any underwritten registration hereunder unless such
Person  (a)  agrees  to sell such Person's securities on the basis provided in
any  underwriting  arrangements  approved by the Persons entitled hereunder to
approve  such  arrangements and (b) completes and executes all questionnaires,
powers  of  attorney, 

                                       11
<PAGE>

indemnities, underwriting agreements and other documents
reasonably  required  under  the  terms  of such underwriting arrangements and
these Registration Rights.

          SECTION 5.2.  Rule 144.  The Company covenants that it will file any
reports  required  to be filed by it under the Securities Act and the Exchange
Act  and  that  it  will take such further action as any Holder may reasonably
request,  all  to  the  extent required from time to time to enable Holders to
sell  Registrable  Securities  without  registration  under the Securities Act
within  the  limitation  of  the exemptions provided by (a) Rule 144 under the
Securities  Act,  as  such  Rule  may be amended from time to time, or (b) any
similar  rule  or  regulation  hereafter  adopted by the Commission.  Upon the
request  of  any  Holder,  the  Company  will deliver to such Holder a written
statement as to whether it has complied with such requirements.

          SECTION 5.3.  Holdback Agreements. (a)Restrictions on Public Sale by
Holder  of  Registrable  Securities.   In the case of an underwritten public
offering,  to  the  extent  not  inconsistent with applicable law, each Holder
whose  securities  are  included in a Registration Statement agrees, except as
part of such public offering, not to effect any public sale or distribution of
the  issue  being  registered  or  a  similar  security of the Company, or any
securities  convertible  into  or  exchangeable  or  exercisable  for  such
securities, including  a  sale pursuant to Rule 144 under the Securities Act,
during  the  14  days prior to, and during the 90-day period beginning on, the
commencement of a public distribution of Registrable Securities, if and to the
extent requested by the managing Underwriter or Underwriters.

           (b)    Restrictions  on  Public Sale by the Company and Others. 
The  Company agrees, on behalf of itself and its Affiliates, (i) not to effect
any  public  sale  or  distribution  of  any securities similar to those being
registered  in  accordance  with  Section  2.1  or  Section 2.2 hereof, or any
securities  convertible  into  or  exchangeable  or  exercisable  for  such
securities, (in each case other than in connection with the Company's Employee
Stock  Purchase  Plan, Employee Stock Option Plan, Non-Employee Director Stock
Ownership  Plan,  401(k)  Plan  or  other  similar  employee  stock  option or
incentive  plan)  during  the  30 days prior to, and during the 180-day period
beginning  on,  the  commencement  of  a  public  distribution  of Registrable
Securities (or such other period of time as may be required by the Underwriter
effecting  such public distribution); and (ii) that any agreement entered into
after  the  date  of  this  Agreement  pursuant to which the Company issues or
agrees  to  issue  any  privately  placed securities shall contain a provision
under  which holders of such securities agree not to effect any public sale or
distribution of any such securities during the periods described in (i) above,
in  each  case including a sale pursuant to Rule 144 under the Securities Act;
provided,  however,  that  the  provisions of this paragraph (b) shall not
prevent  the  conversion or exchange of any securities pursuant to their terms
into or for other securities.

          SECTION 5.4.  Specific  Performance.   Each Holder, in addition to
being  entitled  to  exercise  all  rights  provided herein or granted by law,
including  recovery  of  liquidated  or  other  damages,  will  be entitled to
specific  performance  of its rights under this Agreement.  The Company agrees
that monetary damages would not be adequate compensation for any loss incurred
by  reason  of  a  breach by it of the provisions of this Agreement and hereby
agrees  to  waive  the  defense  in any action for specific performance that a
remedy at law would be adequate.

          SECTION 5.5.  Notices.  Any notice, demand or delivery authorized or
required  by  this  Agreement  shall  be  in writing and shall be given to the
Holder  or  the  Company,  as  the  case may be, at its address (or telecopier
number) set forth below, or such other address (or telecopier number) as shall
have  been  furnished  to  the  party  giving or making such notice, demand or
delivery:

                                      12
<PAGE>

          If to the Company:     American Mobile Satellite Corporation
                                 10802 Parkridge Blvd.
                                 Reston, VA 22091
                                 Telecopy:  (703) 758-6134
                                 Attention:  Randy Segal, General Counsel


          If  to  any Holder:     at the address and telecopy number set forth
                                  in the Guaranty Issuance Agreement.

Each  such  notice,  demand  or  delivery  shall  be effective (i) if given by
telecopy,  when  such telecopy is transmitted to the telecopy number specified
herein  and  the  intended  recipient confirms the receipt of such telecopy or
(ii)  if  given  by  any  other  means, when received at the address specified
herein.

          SECTION 5.6.  No Inconsistent Agreements.  The Company will not on or
after  the date of this Agreement enter into any agreement with respect to its
securities that is inconsistent with the rights granted to the Holders in this
Agreement  or  otherwise  conflicts  with  the provisions hereof.  The Company
hereby  represents  that the rights granted to the Holders hereunder do not in
any  way conflict with and are not inconsistent with the rights granted to the
holders  of the Company's securities under any agreement in effect on the date
hereof.    In  addition,  the  Company  agrees  that  it  will  not  amend its
Certificate  of  Incorporation,  by-laws  or  other governing documents in any
respect  that  would materially and adversely affect the rights of the Holders
hereunder.

          SECTION 5.7.  Further  Assurances.  Each party shall cooperate and
take  such  action as may be reasonably requested by another party in order to
carry  out  the provisions and purposes of this Agreement and the transactions
contemplated hereby.

          SECTION 5.8.   Headings.    The  headings in this Agreement are for
convenience  of  reference  only  and  shall not limit or otherwise affect the
meaning hereof.

          SECTION 5.9.  GOVERNING LAW AND WAIVER OF JURY TRIAL.  THIS AGREEMENT
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK, WITHOUT REGARD TO THE CHOICE OF LAW PRINCIPLES THEREOF.  THE PARTIES
HERETO  IRREVOCABLY WAIVE ANY RIGHT TO A JURY TRIAL WITH RESPECT TO ANY ACTION
OR PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT.

          SECTION 5.10. Severability.  In the event that any one or more of the
provisions  contained  herein, or the application thereof in any circumstance,
is  held  invalid,  illegal  or  unenforceable,  the  validity,  legality  and
enforceability  of  any  such  provision  in  every  other  respect and of the
remaining  provisions  contained  herein  shall  not  be  affected or impaired
thereby.

          SECTION  5.11.  Amendments; Waivers.  Any provision of this Agreement
may  be  amended  or  waived  if,  and only if, such amendment or waiver is in
writing  and  signed,  in  the  case  of  an amendment, by all parties to this
Agreement, or in the case of a waiver, by the party against whom the waiver is
to  be  effective.   No failure or delay by any party 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

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<PAGE>

remedies  herein  provided  shall  be cumulative and not exclusive of any
rights or remedies provided by law.

          SECTION  5.12.   Counterparts.  This Agreement may be executed in any
number  of  counterparts  and  by the parties hereto in separate counterparts,
each  of  which  when so executed shall be deemed to be an original and all of
which taken together shall constitute one and the same agreement.


                           (signature page follows)

                                       14
<PAGE>

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


                              AMERICAN MOBILE SATELLITE CORPORATION


                              By:/s/ Richard J. Burnheimer
                                 _____________________________________
                              Name:  Richard J. Burnheimer
                              Title: Treasurer



                              HUGHES ELECTRONICS CORPORATION


                              By:  /s/  Charles H. Noski
                                 _____________________________________
                              Name:     Charles H. Noski
                              Title:    Senior  Vice President and Chief
                                        Financial Officer



                              SINGAPORE TELECOMMUNICATIONS LTD.


                              By:   /s/ Lim Toon
                                 ____________________________________
                              Name:     Lim Toon
                              Title:    Executive  Vice  President
                                        (International Services)



                              BARON CAPITAL PARTNERS, L.P.

                              By:  Baron  Capital  Management, Inc., a General
                                   Partner


                              By:   /s/ Morty Schaja
                                 __________________________________
                              Name:     Morty Schaja
                              Title:    Vice President



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