How is the angle of attack defined?

The angle of attack is defined as the angle between the airfoil chord line and the direction of the oncoming airflow or airspeed. This concept is crucial in aerodynamics because it directly influences lift generation. As the angle of attack increases, the lift produced by the airfoil also increases up to a certain point, known as the critical angle of attack, beyond which lift can rapidly decrease due to airflow separation, leading to stall conditions.

In the context of aviation and flight dynamics, understanding the angle of attack is essential for pilots to effectively manage flight performance and ensure safety during maneuvers. The correct definition reflects the relationship between the airfoil (such as a wing or rotor blade) and the airflow, which is foundational for analyzing and predicting aircraft behavior during flight.