How Does an Aircraft Spin?

A spin is a condition of stalled flight in which the aircraft descends in a spiral descent. During a spin, the aircraft will be simultaneously rolling, yawing and pitching until recovery is initiated by the pilot.

If an aircraft is either inadvertently or deliberately brought to the stall, a characteristic occurrence may be that one wing will drop. There are several reasons causing this condition, but usually it is the development of yaw when the aircraft is close to, or at the (stalling) critical angle of attack. In a spin, when the aircraft is brought close to a stall, a small rolling action induces a change in the angle of attack, affecting each wing. The lower wing attains a higher angle of attack and approaches the stall sooner, resulting in a sudden drop of this wing.

For a spin to develop, an excessive angle of attack and a positive yawing action are usually required. Generally, the conventional aircraft must be stalled before autorotation takes place.

Once the aircraft has entered a spin, it is quite possible that it will "Auto rotate". This occurs when the dropping wing stalls further, resulting in an increase in drag and less lift. The aircraft then rolls and sideslips as the nose drops. If the pilot does not take corrective action, the rate of rotation will increase with the aircraft in a nose down attitude, increasing the spin.