Definition
Sensors mounted on the leading edge of the wing that detect the change in airflow pattern as the wing approaches a stall, and trigger a cockpit warning (horn, light, or stick shaker) to alert the pilot before the stall occurs. Common designs include a small movable vane or tab that lifts as the stagnation point on the wing moves rearward at high angles of attack.
Plain English
Small sensors on the front edge of the wing that sense when the wing is getting close to stalling and set off a warning in the cockpit so the pilot knows to lower the nose or add power.
Context Anchor
You will see this term in anti-icing and deicing system discussions, on some preflight checks, and when checking that the stall warning system is working before flight.
Derivation
The name describes the job: they detect the lift condition of the wing and warn of an approaching stall. They are sometimes called 'lift detectors' because they sense the airflow that produces lift, not the lift force itself.
Why Pilots Care
Ice forming on an unheated detector can disable the stall warning, leaving the pilot without an early indication of an approaching stall in icing conditions.
Analogy
It is like a small doorbell button on the wing: when the airflow pushes it the right way near a stall, it tells the cockpit to warn you. If ice freezes the button, the warning may not work.
Intuition Check
Do not read “stall” here as an engine stopping. This detector is about an aerodynamic stall: the wing getting too close to losing smooth airflow and lift.
Example Sentence 1
During preflight, the pilot gently checked the stall warning lift detector on the leading edge to make sure it moved freely and triggered the cockpit horn.
Example Sentence 2
As the nose is raised in a practice stall the stall warning lift detectors trigger the horn at the first sign of airflow separation.