Software Growth in Aircraft Total Airplan Signals, Digital, B747400 Analog Words 50000 ◆ Empirical Data FBW Correction 25000 B757767-200 B420 Software size doubles every 18 months Compensating for"FBW offset reduces doubling to 33 monthsSoftware Growth in Aircraft B757/767-200 B777-200 B747-400 B747-200 0 25000 50000 75000 100000 125000 150000 1970 1975 1980 1985 1990 1995 2000 Year Total Airplane Signals, Digital, Analog Words Empirical Data Extrapolation FBW Correction • Software size doubles every 18 months • Compensating for “FBW offset” reduces doubling to 33 months