Angle of Attack (AOA) is defined as the angle between which two lines?

Angle of Attack (AOA) is defined as the angle between which two lines?

• A. The direction of airflow against the wing and the chord
• B. The angle between the direction of airflow against the wing and the horizon
• C. The angle between the direction of airflow against the wing and the wing's chord
• D. The direction of airflow against the wing and the wing's leading edge

Answer: (C)

AOA is the angle between the direction of the relative airflow and the wing’s chord line. The relative airflow is the wind direction as seen by the wing—the air moving past the wing due to the aircraft’s motion. The chord line is the straight line from the wing’s leading edge to its trailing edge, representing the wing’s main orientation. This definition matters because lift and the airflow pattern over the wing depend on how the air meets the wing’s surface along that reference line. Tilting the wing changes how the relative wind aligns with the chord, which changes pressure distribution and lift. The horizon would reflect the aircraft’s attitude, not the aerodynamic angle of attack, and measuring to the leading edge would describe a different geometric relation. So the correct description is the angle formed by the relative wind and the wing’s chord line.

AOA is the angle between the direction of the relative airflow and the wing’s chord line. The relative airflow is the wind direction as seen by the wing—the air moving past the wing due to the aircraft’s motion. The chord line is the straight line from the wing’s leading edge to its trailing edge, representing the wing’s main orientation.

This definition matters because lift and the airflow pattern over the wing depend on how the air meets the wing’s surface along that reference line. Tilting the wing changes how the relative wind aligns with the chord, which changes pressure distribution and lift. The horizon would reflect the aircraft’s attitude, not the aerodynamic angle of attack, and measuring to the leading edge would describe a different geometric relation.

So the correct description is the angle formed by the relative wind and the wing’s chord line.