What aerodynamic phenomena can cause a spin?

A spin is a type of flight condition that occurs when one wing of an aircraft stalls while the other wing retains lift, creating an unbalanced situation that causes the aircraft to rotate about its vertical axis. In this scenario, the wing that is still producing lift creates a difference in aerodynamic forces between the two wings, which leads to the aircraft entering a spin.

When a stall occurs on one wing, that wing will lose lift and begin to drop, while the other wing will generate a higher amount of lift. This imbalance generates a yawing motion, causing the aircraft to roll toward the stalled wing. As the aircraft continues this rotation, it will often reach a point where the angle of attack on the stalled wing becomes critical, resulting in a fully developed spin.

This phenomenon is distinct from other options. For instance, a stall occurring on both wings simultaneously typically leads to a loss of altitude without yawing or rolling motions that initiate a spin. Increased airspeed beyond critical limits or excessive control surface movement can lead to other handling issues or loss of control, but they do not directly cause a spin in the same way that an asymmetrical stall does.