Exhibit 11.1 AMERICAN MOBILE SATELLITE CORPORATION --------------------------------------- COMPUTATIONS OF EARNING PER COMMON SHARE --------------------------------------- (in thousands, except per share amounts) --------------------------------------- Three Months Six Months Ended Ended June 30, June 30, 1997 1996 1997 1996 ---- ---- ---- ---- PRIMARY CALCULATION - ------------------- Net Loss ($26,842) ($43,509) ($53,923) ($73,386) ========= ========= ========= ========= Net Loss per common share ($1.07) ($1.74) ($2.15) ($2.94) ======= ======= ======= ======= Weighted-average common shares outstanding 25,120 25,012 25,115 25,003 ======= ====== ====== ====== FULLY DILUTED CALCULATION - ------------------------- Net Loss (1) ($26,842) ($40,024) ($53,923) ($67,992) ========= ========= ========= ========= Net Loss per common share ($1.07) ($1.59) ($2.14) ($2.69) ======= ======= ======= ======= Weighted-average common shares outstanding 25,182 25,155 25,177 25,258 ======= ====== ======= ====== Three Months Six Months Ended Ended June 30, June 30, (1) Calculated as follows: 1997 1996 1997 1996 ---- ---- ---- ---- Primary net loss $(26,842) ($43,509) ($53,923) ($73,386) Amortization of debt discount -- 1,258 -- 2,253 Interest on convertible debt -- 2,227 -- 3,141 --------- ---------- --------- --------- ($26,842) ($40,024) ($53,923) ($67,992) ========= ========= ========= ========= (2) Calculated as follows: Historical weighted average number of shares 25,120 25,012 25,115 25,003 Assumed exercise of stock options -- 43 -- 108 Assumed exercise of stock purchase warrants 62 100 62 147 -------- -------- ------- ------- 25,182 25,155 25,177 25,258 ======= ======= ======= ======