What defines the "angle of attack" in aviation?

The "angle of attack" is defined as the angle between the chord line of the wing and the relative wind. This measurement is crucial in aviation because it directly affects the lift produced by the wing. When the angle of attack increases, lift increases up to a certain point, beyond which stall may occur. Understanding this concept helps pilots manage the performance of the aircraft during various phases of flight, such as takeoff, cruising, and landing.

The other options do not accurately describe the angle of attack. The angle between the wing and fuselage does not capture the relationship necessary for defining the angle of attack. The angle of descent during landing pertains more to descent profiles rather than lift generation. Lastly, the angle of the runway to the horizon relates to the ground, rather than the aerodynamic principles involving the wing and airflow.