What is the angle of attack defined as?

The angle of attack is defined as the angle between the chord line of a wing and the direction of airflow relative to that wing. This measurement is crucial in aerodynamics because it affects how lift is generated by the wing. As the angle of attack increases, the wing generally produces more lift up to a certain point, known as the critical angle of attack. Beyond this point, lift begins to decrease leading to a stall condition.

Understanding this concept is key for pilots and engineers as it directly influences the performance of an aircraft during various phases of flight, including takeoff, cruising, and landing. The other options do not accurately describe the angle of attack; for instance, the angle between the wing and fuselage pertains to airframe design rather than aerodynamic performance, and angles of descent or bank are related to flight maneuvers rather than the lift generation mechanism.