Free sample · Private Pilot Ground School

How wings make lift — and why they stop

Ten minutes. One interactive wing. The concept behind most loss-of-control accidents.

1. The lift equation

Every wing obeys L = ½ ρ V² S C_L. Air density (ρ) and wing area (S) are mostly fixed in flight, so the pilot controls lift through two levers: airspeed (V) and angle of attack, which sets the lift coefficient C_L. Because speed is squared, small changes in speed matter a lot.

2. The critical angle

Raising the nose increases C_L — until roughly 16° for a typical trainer wing. Past this critical angle of attack, air can no longer follow the curved upper surface. It separates, lift collapses and drag soars. Try it above: push the angle past 16° at any speed.

That is why the stall is not a speed. The published stall speed is only valid at one weight, in level, unaccelerated flight. In a 60° banked turn the load factor is 2 G and the stall speed rises by about 41%.

3. Case study

Base-to-final turn stalls remain a leading cause of fatal general aviation accidents. The typical sequence: overshooting the runway centreline, adding bank and rudder to tighten the turn, pulling back to hold the nose up — and exceeding the critical angle at low height with crossed controls. Recovery: reduce angle of attack first, level the wings, then add power.

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