Accelerated and secondary stalls

Wing can stall well above published (1 g) stall speed.

Accelerated stall (TP 1102 "acceleration stall"):

• Cause: manoeuvre loading wing beyond 1 g (sudden turn, pull-up, other abrupt flight-path change) raises stalling speed above book figure.
• Example: aircraft normally stalling at 50 KT can stall well above 100 KT in steep turn beyond 60° bank.
• Turbulence: upward gust abruptly changes relative airflow, raising angle of attack, like abrupt pull-up. Hence slightly higher-than-normal approach speed recommended in turbulence.
• High-speed stall: high load factor, greater chance of structural damage. Why manoeuvring speed is an AFM limit (TP 1102 Acceleration Stalls).

Secondary stall: second stall during recovery from first.

1. Nose lowered at large angle to recover.
2. Airspeed builds rapidly.
3. Elevator back too rapidly to catch dive.
4. Wing stalls again at much greater speed than original stall.

• Cause: abrupt, premature back pressure before flying speed regained. Pilot re-loads wing mid-recovery.
• Accelerated-stall mechanism (load factor pushes wing back to critical angle of attack), but self-inflicted.

Trap: rushing recovery. Snatching nose up to stop dive or get stall "over with" reloads wing before flying speed returns: re-stalls at higher speed than first stall.

Practice