Definition

A deep stall, sometimes referred to as a super stall, is a particularly dangerous form of stall that results in a substantial reduction or loss of elevator authority making normal stall recovery actions ineffective. In many cases, an aircraft in a deep stall might be unrecoverable. This phenomenon affects certain aircraft designs, most notably those with a T-tail configuration.

Description

As the angle of attack of any aerofoil section is increased, the lift will also increase up to a point known as the critical angle. At this angle of attack (typically 15° to 20° for most aerofoil sections) the airflow separates from the upper surface of the wing and this condition is known as a stall. At the stall, lift is significantly reduced, drag is significantly increased and the airflow across, and behind, the wing becomes turbulent.