Which two primary factors must be present for an aircraft to spin?

A spin occurs when an aircraft is in a stalled condition and is subjected to a yawing motion, which can often be caused by one wing being more stalled than the other. For a spin to develop, the aircraft must firstly be at a stalled angle of attack (AOA); this means that the wings are no longer generating sufficient lift, typically due to exceeding the critical angle of attack. Secondly, yaw must be present; this can happen when a pilot inadvertently applies rudder or when the aircraft experiences uneven lift, leading to one wing dropping.

In summary, both a stalled AOA and yaw are essential for initiating a spin. Without a stall, the aircraft would typically recover from any disturbance or rotation, and without yaw, it wouldn’t generate the necessary asymmetrical lift that leads to a spin. This dynamic is critical for pilots to understand as it highlights the importance of maintaining control inputs during critical phases of flight, such as stall recovery.