Definition
The angle between the chord line of an airfoil (the straight line from its leading edge to its trailing edge) and the direction of the oncoming relative wind. It is the angle at which the wing meets the air flowing past it, and it is the primary factor controlling how much lift the wing produces. When angle of attack exceeds the wing's critical angle, the airflow separates from the upper surface and the wing stalls.
Plain English
The angle at which the wing is tilted into the oncoming air. Tilt the wing up more, and it pushes harder against the air -- up to a point. Past that point, the air can no longer follow the wing's shape, and the wing stops lifting properly.
Context Anchor
Seen in lift, stall, slow flight, takeoff, landing, and maneuvering discussions.
Derivation
From the Latin 'angulus' (angle) and the everyday English 'attack' meaning to engage or meet head-on. The wing 'attacks' the oncoming air at a particular angle. The phrase captures the geometry simply: it's the angle at which the wing meets the air.
Why Pilots Care
It controls how much lift the wing produces and exactly when a stall occurs.
Analogy
Hold your hand flat out a car window. If you tilt the front of your hand up a little, the air pushes it differently. That tilt into the oncoming air is the basic idea of angle of attack.
Grounding Statement
When the pilot changes how the wing meets the oncoming air, the angle of attack changes.
Intuition Check
Do not assume AOA is the same as nose-up attitude. The airplane’s nose position is what you see; AOA is the angle between the wing and the airflow meeting it.
Example Sentence 1
As the pilot raised the nose during the slow flight demonstration, the angle of attack increased and the stall warning began to chirp.
Example Sentence 2
Holding a lower angle of attack let the airplane maintain higher speed without approaching a stall.