Secondary Stall

What is a Secondary Stall?

A secondary stall happens when, during the recovery from an initial (primary) stall, the pilot applies excessive back pressure on the control column. This causes the angle of attack to exceed the critical value again, resulting in a second stall before the aircraft has fully regained normal flight.

Causes of Secondary Stall

• Incorrect Recovery Technique: The most common cause is pulling back too aggressively on the control column after the initial stall, often due to a desire to minimise altitude loss.
• Premature Pitch-Up: Attempting to return to level flight too soon, before airflow over the wings is fully restored, can lead to a secondary stall.
• Lack of Situational Awareness: Not recognising that the aircraft is still close to the critical angle of attack increases risk.

Symptoms and Recognition

• Stall Warning Activation: Continuous or repeated stall warning (stick shaker, horn, or light).
• Buffet: Noticeable airframe vibration or buffet.
• Loss of Pitch Authority: Difficulty in raising or lowering the nose as expected.
• Uncommanded Aircraft Movements: Pitch down, roll, or inability to arrest descent.

Secondary Stall vs. Deep Stall

A secondary stall is a result of pilot input error during recovery, while a deep stall (super stall) is an aerodynamic phenomenon often associated with T-tail or swept-wing aircraft, where recovery may be impossible due to elevator blanking.

Prevention and Correct Recovery

• Reduce Angle of Attack: Always ensure the nose is lowered sufficiently to break the stall.
• Avoid Over-Correction: Do not pull up sharply after the initial recovery; allow the aircraft to regain normal airflow and speed before resuming climb or level flight.
• Monitor Airspeed and Attitude: Maintain awareness of aircraft state throughout the recovery process.

Operational Relevance

Secondary stalls are most commonly encountered during flight training but can occur in any phase of flight if recovery procedures are mishandled. Mastery of stall recovery is essential for safe aircraft operation.