Stalling

A Stall

A stall occurs when an aerofoil exceeds its critical angle of attack.

As the critical angle of attack is exceeded, airflow over the aerofoil separates, causing:

• a significant reduction in lift
• a large increase in drag
• a loss of normal control effectiveness

At low angles of attack, the airflow remains attached over most of the aerofoil and the separation point is towards the rear.

As the angle of attack increases, the separation point moves forward and the turbulent wake becomes larger.

When the critical angle of attack is exceeded, the aerofoil stalls.

Key point

An aircraft stalls because the critical angle of attack has been exceeded.

A stall can occur:

• at any airspeed
• at any attitude
• at any power setting

A low airspeed by itself does not cause a stall.

Stall Recovery

Because a stall is caused by exceeding the critical angle of attack, the first action in the recovery is to reduce the angle of attack.

This is achieved by releasing back pressure or applying sufficient forward pressure to lower the nose.

Once the angle of attack has been reduced:

• apply power as required
• level the wings as appropriate
• allow the airspeed to increase
• return smoothly to the desired flight path