What are the two main requirements for a spin to occur?

For a spin to occur, the aircraft must first reach a stalled condition, which happens when the wings exceed their angle of attack beyond the critical angle, causing a loss of lift. The second requirement is uncoordinated flight, which occurs when the aircraft is not aligned with the direction of flight, often caused by improper use of the controls by the pilot. In this situation, one wing may be producing more lift than the other, leading to an imbalance. When a stall occurs in this uncoordinated state, the aircraft will start to rotate about its vertical axis, thus leading to a spin.

Understanding the relationship between stall and uncoordinated flight is crucial for pilots, as it highlights the importance of aircraft control and awareness of the aircraft's attitude in various flight regimes. This knowledge can aid in both preventing spins and managing their recovery if they do occur.