What is the cause of a spin in aviation?

In aviation, a spin is primarily caused by an aggravated stall that leads to autorotation. During a stall, the wings of the aircraft exceed their critical angle of attack, causing a significant reduction in lift. If the aircraft enters a yawing motion while it is in a stalled condition, the aerodynamic forces acting on the wings can cause one wing to drop more than the other. This asymmetrical lift further exacerbates the situation, causing the aircraft to begin to rotate around its vertical axis—this is referred to as autorotation.

In a spin, the aircraft enters a continuous rotation around its vertical axis, characterized by a descent and an oscillation in yaw due to the differing lift and drag on the wings. Understanding this concept is crucial for pilots, as recovery techniques from a spin require specific knowledge of the aerodynamics involved and the correct inputs to return the aircraft to controlled flight.

This understanding highlights the importance of managing aircraft control during low-speed maneuvers and ensures pilots remain aware of the aircraft's angle of attack and airspeed to prevent spins from occurring. Other choices like excessive vertical speed, lack of sufficient lift, or overloading the aircraft may contribute to loss of control but do not directly define the mechanics by which a spin is initiated.