Plain English Meaning

A loud beep or buzzing sound in the cockpit that warns the pilot the wing is getting close to stalling. It activates before the stall actually happens, giving the pilot time to react.

Full Definition

A cockpit warning device that produces an audible tone when the airplane's angle of attack approaches the critical angle at which the wing will stall. It is triggered either by a small movable vane on the wing's leading edge that is pushed up by the changing airflow at high angles of attack, or by an electrical pressure sensor wired to a horn or buzzer in the cabin.

Context Anchor

You hear or test the stall horn during checks, , , and sometimes on if the airplane gets too slow or the nose is held too high.