Definition
The condition in which the smooth flow of air over a wing or other airfoil breaks away from the surface, becoming turbulent and disorganized. When this happens, the airfoil produces less lift and more drag, and control effectiveness is reduced. Airflow separation is what occurs at the point of stall, and it can also be triggered prematurely by ice, surface damage, or contamination disrupting the airfoil shape.
Plain English
The air stops flowing smoothly over the wing and instead breaks away into a messy, swirling pattern. When that happens, the wing makes less lift and more drag, and the controls feel less responsive.
Context Anchor
Seen in discussions of stalls, wing and tail icing, aircraft handling, and how ice changes the way air moves over an airfoil.
Derivation
From everyday English: the airflow literally separates from the surface it was hugging. Naming it this way is a clue — the air is no longer attached to the wing.
Why Pilots Care
It is the direct mechanism behind stalls and loss of control when ice accumulates on the wings.
Grounding Statement
Picture air sliding smoothly over a clean wing, then hitting rough ice and breaking away instead of staying close to the surface.
Intuition Check
Airflow separation does not mean the air splits into two harmless paths. It means the smooth flow breaks away from the lifting surface, which can reduce lift and control.
Example Sentence 1
Ice on the leading edge changed the wing's shape and caused early airflow separation, so the aircraft stalled at a higher airspeed than the pilot expected.
Example Sentence 2
The pilot recognized the onset of airflow separation by the sudden loss of elevator effectiveness.