Angle of attack

The angle between an aircraft wing or other body’s reference line and the direction of oncoming airflow. It helps determine aerodynamic forces and changes with the body’s orientation to the flow.

Lift (force): The aerodynamic force component perpendicular to the direction of relative airflow. Increasing angle of attack usually increases lift until airflow separation disrupts the trend.
Relative wind: The airflow direction relative to an aircraft moving through the surrounding air. Angle of attack is measured against this local oncoming flow, not the horizon.
Angle-of-attack indicator: An instrument that displays an aircraft's angle of attack, often relative to its stall margin. It gives pilots a direct cue about wing loading and proximity to critical angle.
Angle of incidence (aeronautics): The fixed angle between an aircraft wing's chord line and the fuselage reference line. Incidence is built into the aircraft; angle of attack changes with flight attitude and airflow.
Boundary layer: The thin region of fluid near a surface where viscosity strongly affects flow speed. Its ability to remain attached helps determine how much angle of attack a wing can sustain.
Chord line: The straight line joining the leading and trailing edges of an airfoil section. For a wing section, this is the usual reference line used to define angle of attack.
Aircraft stall warning: An aircraft system that alerts pilots to conditions approaching an aerodynamic stall. Warnings often rely on angle-of-attack sensing rather than airspeed alone.
Aerodynamic angle: An angle describing the orientation of a body or surface relative to an airflow direction. Angle of attack is one specific aerodynamic angle, defined in a chosen plane and reference frame.
Flow separation: The detachment of fluid flow from a surface when the near-surface flow can no longer follow it. Rising angle of attack can create an adverse pressure gradient that separates airflow from the wing.
Airfoil: A cross-sectional shape designed to generate aerodynamic forces as fluid flows around it. Angle of attack is commonly introduced through the orientation of an airfoil in airflow.

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