The angle of attack (AoA) is the angle between the wing's chord line and the oncoming airflow. It is one of the most important concepts in understanding how a wing generates lift.
How It Works#
Every wing has a chord line: an imaginary straight line from the leading edge to the trailing edge. As the wing moves through the air, the direction of the oncoming airflow is called the relative wind. The angle between these two lines is the angle of attack.
As AoA increases, the wing deflects more air downward. This produces more lift, up to a point. That point is called the critical angle of attack. Most general aviation wings reach the critical AoA somewhere between 15° and 20°.
Beyond the critical AoA, airflow separates from the upper wing surface. Lift drops sharply. This is a stall. It is not about airspeed — a wing can stall at any speed if the critical AoA is exceeded.
Pilots control AoA primarily through back pressure on the elevator. Pulling back raises the nose, which increases AoA. Pushing forward lowers it.
Example in Aviation#
A student pilot is practicing slow flight. The instructor notices the airspeed is low and the nose is high. The wing is approaching the critical angle of attack. A stall warning horn sounds, triggered by an AoA sensor near the leading edge.
The instructor pushes the controls forward slightly. This reduces AoA, reattaches the airflow, and restores lift. The aircraft recovers cleanly.
Why It Matters#
Stall awareness is built entirely on understanding AoA. A pilot who thinks "stall equals slow speed" is working with incomplete information. A steep turn at cruise speed can produce a stall if back pressure drives AoA past the critical angle.
Modern aircraft increasingly display AoA directly in the cockpit. Understanding what that number means helps pilots make better decisions at every phase of flight, from takeoff to landing.
Key Takeaways#
- Angle of attack is the angle between the chord line and the relative wind.
- Increasing AoA increases lift, but only up to the critical angle.
- Beyond the critical AoA, the wing stalls regardless of airspeed.
- Pilots control AoA through elevator input, not throttle.
- Stall recognition depends on understanding AoA, not just watching the airspeed indicator.