Definition
A region of disturbed, irregular airflow trailing behind a wing or other surface, in which the air no longer moves in smooth, parallel layers but instead breaks into swirling, churning eddies. With flaps extended, the wing produces a stronger and more pronounced turbulent wake behind and below the trailing edge.
Plain English
Air that has been stirred up into a churning, swirling mess instead of flowing smoothly. When flaps are down, the wing leaves a bigger trail of this stirred-up air behind it.
Context Anchor
Seen in flap discussions, especially when explaining how extended flaps increase drag and change airflow around the wing.
Derivation
Turbulent comes from the Latin turbulentus, meaning 'restless' or 'stirred up,' from turba ('a crowd, commotion'). The image is of a disorderly crowd rather than an orderly line — which fits exactly what the air is doing in this kind of flow.
Why Pilots Care
The pattern increases drag and can alter stall behavior, directly affecting approach speed and landing distance.
Grounding Statement
Picture smooth water flowing past a paddle, then the paddle tilts down — the water behind it suddenly breaks into swirls and froth. That broken-up flow is the turbulent air pattern behind a wing with flaps extended.
Intuition Check
Do not read pattern here as a traffic pattern or planned route. In this context, it means the shape and behavior of disturbed air moving around the airplane.
Example Sentence 1
Lowering the flaps creates a turbulent air pattern behind the wing, which is one reason drag increases sharply.
Example Sentence 2
The handbook diagram illustrated how the turbulent air pattern grows larger with greater flap extension.