Definition
An onboard device that alerts the pilot when the wing's angle of attack approaches the critical angle at which the wing will stop producing sufficient lift. The warning is typically delivered as an audible horn, a stick shaker, an illuminated light, or a combination of these, and is designed to activate slightly before the actual stall occurs.
Plain English
A built-in alarm that lets the pilot know the wing is about to stop flying properly, giving them a chance to lower the nose and recover before a full stall happens.
Context Anchor
You encounter it during preflight checks, slow-speed practice, approach and landing, and any situation where the airplane may be getting too slow or too nose-high.
Derivation
“Stall” originally meant to stop or come to a standstill. In aviation, it does not mean the engine stopped; it means the wing’s smooth airflow has broken down enough that lift drops off. That makes “stall warning system” a warning system for the wing approaching that condition.
Why Pilots Care
Provides an early, reliable cue to prevent an unintentional stall, especially when visual or seat-of-the-pants sensations are masked by turbulence, distraction, or instrument flight.
Intuition Check
Do not assume “stall” means the engine quits. In this term, “stall” means the wing is getting close to losing lift because the airflow over it is no longer smooth enough.
Example Sentence 1
As the pilot raised the nose during slow flight practice, the stall warning horn sounded, prompting them to lower the nose and add power.
Example Sentence 2
The instructor pointed out the small vane on the wing leading edge that triggers the stall warning system in the training airplane.