Definition
A sensor mounted on the leading edge of a wing that activates the stall warning system when the angle of attack approaches a stall. As the airflow over the wing changes near a stall, the airflow shifts upward across the leading edge and lifts a small vane or closes a contact in the switch, completing an electrical circuit that triggers a horn, light, or other warning in the cockpit.
Plain English
A small sensor on the front edge of the wing that detects when the wing is getting close to stalling and turns on a warning in the cockpit so the pilot knows to act before the wing actually stalls.
Context Anchor
Pilots encounter this term when learning stall warning systems and when checking that the stall warning works during preflight inspection.
Derivation
In aviation, a “stall” means the wing is no longer getting smooth airflow enough to make normal lift. “Warning” means advance notice, and “switch” means an electrical device that turns something on or off. Together, the term points to the device that turns on the warning before the wing stalls.
Why Pilots Care
It provides early warning so the pilot can lower the nose and restore airflow before a full stall develops and control is lost.
Intuition Check
A stall warning switch does not prevent a stall and it does not mean the engine has stopped. It only senses a near-stall condition at the wing and turns on the warning.
Example Sentence 1
During preflight, the pilot gently lifted the stall warning switch on the wing's leading edge and confirmed the warning horn sounded in the cockpit.
Example Sentence 2
On final approach the stall warning switch activated, prompting the pilot to add power and reduce pitch attitude.