What causes an airplane wing to stall?

An airplane wing stalls when it exceeds a critical angle of attack, which refers to the point at which the airflow over the wing begins to separate from the wing's upper surface. This separation disrupts the smooth airflow necessary for generating lift. As the angle of attack increases beyond this critical point, the wing loses its ability to produce lift effectively, leading to a stall condition.

In normal flight operations, pilots must be aware of the critical angle of attack, as it varies slightly across different aircraft and under varying conditions. When the angle exceeds this limit, regardless of the actual weight of the aircraft, the wing's lift will start to decline, and the aircraft may descend or lose altitude uncontrollably.

While other factors like weight, engine power, or turbulence can influence flight stability and performance, they do not directly cause a stall in the context of wing aerodynamics. Instead, the stall is specifically related to exceeding that defined angle, making it a crucial concept for pilots and aviation mechanics to understand for safe flight operations.