Definition
The angle of attack at which the airflow over a wing separates from the upper surface to the point that the wing can no longer produce enough lift to support the aircraft. Beyond this angle, lift decreases sharply and the wing is said to be stalled. The stalling angle for a given wing is essentially fixed by its shape and is not changed by airspeed, weight, or aircraft attitude.
Plain English
The point where the wing is tilted into the oncoming air so steeply that the air can no longer flow smoothly over the top of it. When that happens, the wing stops producing the lift needed to keep the aircraft flying.
Context Anchor
Seen in lift, stall, and angle-of-attack discussions; in flight, it matters whenever the aircraft is slowed, pulled up, or turned sharply.
Derivation
From 'stall,' which originally meant to come to a standstill or stop functioning (as in an engine stalling). Applied to a wing, it describes the moment the wing stops doing its job of producing lift. 'Angle' here refers specifically to the angle of attack — the angle between the wing and the relative wind.
Why Pilots Care
Recognizing the approach to this angle prevents unintentional stalls that can cause sudden loss of altitude or control.
Analogy
If you hold your hand out a car window and tilt it slightly, the air flows over it smoothly. Tilt it too steeply, and the airflow breaks up; the stalling angle is like that too-steep point for a wing.
Grounding Statement
Picture the wing meeting the airflow more and more steeply until the air can no longer stay smooth over the top surface.
Intuition Check
Stalling angle is not about the engine stopping. It is about the wing meeting the airflow at too steep an angle to keep producing normal lift.
Example Sentence 1
During slow flight practice, the instructor demonstrated how the wing reached its stalling angle and the nose dropped as lift was lost.
Example Sentence 2
In instrument flight, the pilot watches airspeed closely to avoid reaching the stalling angle in turbulence.