Recognizing an approaching stall
Stalls give warning. Most aircraft lack an AoA indicator, so airspeed, feel, sound, and sight guide the approach (TP 1102).
Angle of attack (AoA) (TP 1102):
- Symptoms start at about 15 to 16°, just short of the critical AoA.
- Critical AoA (stall itself): about 17°.
Same borderline condition, two names (close to stall, not fully stalled):
| Source | Term |
|---|---|
| TP 1102 | Imminent stall |
| AC 700-031 | Approach-to-Stall, bordered by stall warning and the aerodynamic stall itself (s.2.3(1)(d)) |
Symptoms of an approaching stall:
- Controls go mushy (TP 1102):
- Elevator and aileron response progressively less "live"; more movement needed for same result as speed decreases.
- Ailerons lose effectiveness first: lack of response most noticeable, worse as speed drops (TP 1102 Ex.11 Slow Flight; AC 700-031 s.7.2(1)(h)).
- At the full stall: outright lack of pitch authority and lack of roll control (AC 700-031 s.2.3(1)(p)(ii), (iii)).
- Stall warning device (TP 1102):
- Audible horn or visual light, fitted to most aircraft.
- Activates before the wing stalls: built-in margin to correct in time.
- On equipped aircraft, stick pusher activation also characterizes the stall itself (AC 700-031 s.2.3(1)(p)(vi)).
- Stick pusher: safety system that applies downward elevator pressure to stop the aeroplane exceeding a predetermined AoA; helps avoid, identify, or recover from a stall (AC 700-031 s.2.3(1)(u)).
- Buffet: turbulent airflow beats on the airframe, felt and/or heard as a shudder; strength varies by aircraft type (TP 1102).
- Height loss despite back pressure: aircraft keeps sinking with column held back; wing cannot produce enough lift to arrest descent (TP 1102).
- Aircraft less stable: as approach to stall develops, expect degraded, ineffective, or even reversed control inputs, or uncontrolled departures from stable flight in roll or pitch (AC 700-031 s.7.3(1)).
Uncoordinated flight (improper use of rudder): classic factor leading to a stall event (AC 700-031 s.7.2(1)(b)(xiii)).
First indication of a stall: whichever shows first, aural, tactile, or visual, natural or from a warning device (AC 700-031 s.2.3(1)(h)). Cue to act: do not wait for more cues or the stall.
Trap: trusting the horn alone. One cue among several; a normal wing stall also gives mushy controls and buffet, so a failed or misadjusted device still leaves cues. (Tailplane stall is the exception, see tailplane-stall: none of these.)
References
- TP 1102 (Flight Training Manual) Ex.12 Stalls, "Symptoms of an Approaching Stall"
- AC 700-031 s.2.3(1)(h), (s)
- TP 1102 Ex.11 Slow Flight
- AC 700-031 s.7.2(1)(h)