Stall horn

In aviation, a stall horn is an audible annunciator in the cockpit of an aircraft that warns the pilot when the angle of attack of the aircraft's wings approaches the critical threshold of an aerodynamic stall. Most stall horns are designed to sound just before the critical angle of attack is reached, and thus warn of an impending stall rather than signal the stall itself, thereby giving the pilot the opportunity to avoid a stall rather than recover from one. The type of sound or announcement made by the stall horn varies from one aircraft to another, as does the exact mechanism that activates and operates the horn.

Some aircraft incorporate a whistle-like device directly on the wings that produces a characteristic sound, audible from within the cockpit, when the angle of attack approaches the critical angle, thus acting as a stall horn of sorts.