Aviation Terminology - Angle of Attack

Angle of attack is an important concept in flying. It affects flying performance. Incorrect setting of angle of attack may lead to stall.

Before discussing about the angle of attack, we should better familiarize ourselves with some terminologies of wing.

Leading Edge: It is the point of a wing which first contacts with air. 

Trailing Edge: It is point at the end of a wing which splitting up air meets again.

Chord Line: An imaginary straight line connecting the leading and trailing edges.

Camber Line: An imaginary curved line connecting the leading and trailing edges. Its separation between the upper and lower surfaces are the same at every point.

Relative Wind: The direction of relative wind is always opposite to the flight direction.

Angle of Attack: It is the angle between chord line and relative wind.

Still remember the Lift Equation? The lift coefficient (CL) is influenced by factors like the angle of attack.

In general, the lift coefficient increases as angle of attack increases, until to a point known as Critical Angle of Attack (15-16 degrees). 

For typical aircraft like many airliners, their wing's ability to generate lift after the critical angle greatly diminishes. It is because air can no longer adhere to the wing surface smoothly and form turbulence. Lift is lost and the aircraft stalls.