Stall — Flight States

The wing exceeds its critical angle of attack. Airflow over the upper surface separates, lift collapses, and drag rises sharply. A stall is not about airspeed — it is about angle of attack.

What actually happens

At low angles of attack, airflow stays attached to the wing's upper surface, creating a region of low pressure that generates lift. As angle of attack increases, the airflow must curve more sharply over the leading edge. At the critical angle of attack — typically 15–18° for most airfoils — the flow can no longer follow the wing's curve and separates, becoming turbulent. The low-pressure region collapses and lift drops dramatically.

The critical misconception

Stall speed is commonly quoted as a single number, but stall speed changes with conditions. Any aircraft can stall at any airspeed if the angle of attack is high enough. The classic stall at low speed happens because at low speed, maintaining lift requires high angle of attack. But a steep turn or abrupt pull-up can stall the aircraft well above the published stall speed.

Quick reference

Cause	Angle of attack exceeds critical AoA (~15–18° for most airfoils)
Warning signs	Buffet, mushy controls, stall warning horn
Recovery	Reduce angle of attack (push forward), add power
Stall speed increases with	Bank angle, load, weight, ice/contamination on wing

Accelerated stall: A steep turn at low altitude combines high bank angle (raising stall speed) with low altitude (no room for recovery). This is one of the most dangerous situations in general aviation. The aircraft can stall at an airspeed well above the normal stall speed that appears on the airspeed indicator.

Related terms

Lift — what collapses in a stall
Pitch — angle of attack is driven by pitch attitude and airspeed
Turn — steep turns increase load factor and thus stall speed

← Turn Next concept: Forces →