A stall happens when the wing exceeds its critical angle of attack. The smooth airflow over the top of the wing separates, lift falls off sharply, and the airplane can no longer sustain level flight. A stall is a function of angle of attack alone — it can occur at any airspeed, any attitude, and any power setting.
Recognizing a stall
Common cues include a nose-high attitude, decreasing airspeed, mushy or sloppy flight controls, a stall-warning horn or light, and often a buffet felt through the airframe as disturbed air strikes the tail. The recovery is the same regardless of how the stall was entered.
Stall recovery
- Reduce the angle of attack by decreasing pitch — this is the essential action that ends the stall.
- Add power as appropriate to minimize altitude loss.
- Level the wings and return to coordinated flight, then resume a normal climb or cruise.
From stall to spin
A spin is an aggravated stall that results in autorotation: the airplane descends in a corkscrew path while rotating about a vertical axis. A spin requires two ingredients — the wing must be stalled, and the airplane must be uncoordinated (yawing) at the point of stall. In an uncoordinated stall, one wing is more deeply stalled than the other, so it drops and the airplane begins to rotate.
The standard, generic spin recovery is often summarized by the acronym PARE: reduce Power to idle, neutralize the Ailerons, apply full Rudder opposite the direction of rotation, and briskly move the Elevator forward to break the stall. Once rotation stops, neutralize the rudder and recover from the resulting dive. Pilots should always follow the specific spin-recovery procedure in their airplane’s flight manual, as techniques vary by type.
The most effective defense against an inadvertent spin is to keep the airplane coordinated and avoid an accelerated stall, especially in the traffic pattern where altitude for recovery is limited.