Definition
The acute angle formed between the chord line of an airfoil and the relative wind — the direction of the airflow meeting the wing. Angle of attack determines how much lift the wing produces at a given airspeed, and exceeding the critical angle of attack causes the wing to stall regardless of airspeed or aircraft attitude.
Plain English
The angle at which the wing meets the oncoming air. The steeper this angle, the more the wing 'bites' into the air — up to a point. Past that point, the airflow breaks away from the wing and lift collapses.
Context Anchor
Seen in discussions of lift, slow flight, stalls, takeoff and landing, turns, and aircraft control.
Derivation
From Latin angulus (corner) and the everyday English 'attack' meaning to engage or meet head-on. Here, 'attack' simply describes how the wing meets the air — not anything aggressive. The wing 'attacks' the relative wind at a measurable angle.
Why Pilots Care
Determines lift and drag produced by the wing and sets the stall point independent of airspeed.
Analogy
Hold your hand flat out a car window and slowly tilt the front edge up. The more you tilt it into the moving air, the greater its angle to the airflow becomes.
Grounding Statement
Picture the wing moving through the air: angle of attack is the wing's tilt compared with the air actually flowing past it.
Intuition Check
Do not assume angle of attack means the airplane's nose-up attitude. It means the angle between the wing's reference line and the airflow meeting the wing.
Example Sentence 1
As the pilot raised the nose during slow flight, the angle of attack increased and the stall warning began to sound.
Example Sentence 2
At the critical angle of attack the wing stalled even though airspeed remained above stall speed.