Exhibit 11.1 AMERICAN MOBILE SATELLITE CORPORATION --------------------------------------- COMPUTATIONS OF EARNING PER COMMON SHARE --------------------------------------- (in thousands, except per share amounts) --------------------------------------- Three Months Nine Months Ended September 30, Ended September 30, 1996 1995 1996 1995 ------------------- ------------------- PRIMARY CALCULATION - ------------------------- Net Loss $(30,003) $(12,502) $(103,388) $(26,964) ========= ========= ========== ========= Net Loss per common share $ (1.20) $ (.50) $ (4.13) $ (1.08) ========= ========= ========== ========= Weighted-average common shares outstanding 25,065 24,941 25,024 24,884 ========= ========= ========== ========= FULLY DILUTED CALCULATION - ------------------------- Net Loss(1) $(30,003) $(12,502) $ (97,994) $(26,964) ========= ========= ========== ========= Net Loss per common share $ (1.19) $ (.50) $ (3.88) $ (1.07) ========= ========= ========== ========= Weighted-average common shares outstanding(2) 25,200 25,155 25,229 25,099 ========= ========= ========== ========= (1) Calculated as follows: Three Months Nine Months Ended September 30, Ended September 30, 1996 1995 1996 1995 ------------------- ------------------- Primary net loss $(30,003) $(12,502) $(103,388) $(26,964) Amortization of debt discount -- -- 2,253 -- Interest on convertible debt -- -- 3,141 -- --------- --------- ---------- --------- $(30,003) $(12,502) $ (97,994) $(26,964) ========= ========= ========== ========= (2) Calculated as follows: Historical weighted average number of shares outstanding 25,065 24,941 25,024 24,884 Assumed exercise of stock options 35 57 105 58 Assumed exercise of stock purchase warrants 100 157 100 157 ========= ======== ========== ========= 25,200 25,155 25,229 25,099 ========= ======== ========== =========