What is the critical angle of attack for most training aircraft?

Typical light-aircraft airfoils reach their critical angle of attack somewhere between 15° and 18°. The exact value depends on airfoil geometry, Reynolds number, and flap setting.

Can an airplane stall at cruise airspeed?

Yes. In an accelerated stall — for example a steep, aggressive pull-up — the wing can exceed its critical angle of attack at any indicated airspeed the airframe can survive.

Why do we still teach stall speed if the wing stalls at an angle?

Published V_S values assume 1 g, unaccelerated flight at a specific weight and configuration. They give pilots a useful benchmark, but the underlying event is always an angle-of-attack event.

What does an angle-of-attack indicator actually measure?

It measures the local flow angle at a vane or pressure port and relates it to the wing's critical angle of attack, usually displayed as a normalized margin — green, yellow, red — so the pilot sees how much α headroom remains.

AERO-02 · Aerodynamics

Angle of Attack and the Stall

The wing does not stall at a speed; it stalls at an angle. Why the critical angle of attack is the single most important number in aerodynamics.

By Dmitry ShteynWisconsin, USAPublished April 21, 20268 min read

The most persistent misconception in general aviation is that stall is a function of airspeed. It is not. A wing stalls when — and only when — it exceeds its critical angle of attack (α_crit). That can happen at any airspeed, any attitude, any power setting.

Fig. 1Angle of attack (α) is the angle between the chord line and the relative wind — not the pitch attitude relative to the horizon.

Why the curve collapses

Below α_crit, the airflow remains attached to the upper surface of the wing and the coefficient of lift rises approximately linearly with angle of attack. Once α exceeds the critical value, flow separates from the upper surface. Lift collapses; drag climbs sharply.

Fig. 2The lift curve. The vertical line at α_crit is the boundary between flying and falling.

Load factor and the accelerated stall

In a 60° banked level turn the wing carries 2 g. To hold altitude the pilot must pull, increasing angle of attack toward — and sometimes past — the critical value. The published stall speed increases by roughly the square root of the load factor: V_S · √n. At 2 g, stall speed is 1.41 × the 1 g value.

Recovery is unloading, then recovering

Regardless of attitude, airspeed, or configuration, stall recovery begins the same way: reduce angle of attack. Push forward on the controls to unload the wing, level the wings with coordinated aileron, and only then add power and climb away. Pulling out of a stall re-stalls the wing.

Foundational context lives in The Four Forces of Flight. For the human side of stall avoidance, see IMSAFE and the PAVE Checklist.

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Educational content, not flight instruction. Consult a certificated flight instructor and current official publications.

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