In what flight condition must an aircraft be placed in order to spin?

• A. Stalled
• B. Banked 90 degrees
• C. Inverted
• D. Clean configuration

Answer: (A)

The key idea is that a spin can only happen once the wing is stalled. When the angle of attack exceeds the critical value, airflow over the wing separates, lift drops, and control effectiveness is lost. If there’s also some yaw and asymmetry between wings (often due to imperfect coordination), the airplane can rotate about the vertical axis as it slides downward—this is a spin.

Being banked at 90 degrees, flying inverted, or simply in a clean configuration doesn’t by itself cause a spin. A stall can occur with the wings level or in various configurations, but a sustained spin requires that stalled condition with the right yaw/roll dynamics. So the best answer is stalled.