The Speed Trim System (STS) operates most frequently during takeoffs & go-arounds. Conditions for speed trim operation are:
A.A.Airspeed between 100 KIAS and Mach 0.68, 10 seconds after takeoff, 5 seconds following release of trim switches, N1 above 60%, autopilot not engaged, sensing of trim requirement
B.B.Airspeed between 100 KIAS and Mach 0.68, 10 seconds after takeoff, 5 seconds following release of trim switches, N1 above 40%, sensing of trim requirement
C.C.Airspeed between 100 KIAS and Mach 0.68, 15 seconds after takeoff, 5 seconds following release of trim switches, N1 above 60%, sensing of trim requirement
D.D.Airspeed between 100 KIAS and Mach 0.68, 10 seconds after takeoff, 5 seconds following release of trim switches, N1 above 40%, autopilot not engaged, sensing of trim requirement
正确答案是A