American Mobile Satellite Corporation
                            10802 Parkridge Boulevard
                           Reston, Virginia 20191-5416



                                                            January 23, 1998



Securities and Exchange Commission
450 Fifth Street, N.W.
Judiciary Plaza
Washington, D.C. 20549

                  Re:      American Mobile Satellite Corporation
                           Registration Statement on Form S-3
                           (Registration No. 333-1120)

Ladies and Gentlemen:

In accordance  with Rule 477  promulgated  under the  Securities Act of 1933, as
amended,  American Mobile  Satellite  Corporation  ("AMSC") hereby withdraws its
Registration Statement on Form S-3 (Registration No. 333-1120), as amended, that
was originally filed with the Securities and Exchange  Commission on February 7,
1996. AMSC is withdrawing the Registration  Statement because it does not intend
to  conduct  the  offering  of  shares  of  Common  Stock  contemplated  in  the
Registration Statement at this time. No shares of Common Stock of AMSC have been
issued or sold under the Registration Statement.

If you have any  questions  with  respect to this  letter,  please  call  either
Richard  E.  Baltz of the law firm of Arnold & Porter at  202-942-5124  or me at
703-758-6130.

                                           Sincerely,

                                           AMERICAN MOBILE SATELLITE CORPORATION

                                           By:  /s/RANDY S. SEGAL
                                                Randy S. Segal
                                                Vice President, General Counsel


cc:      Gary Parsons, President and Chief Executive Officer