Definition
Hinged or movable surfaces on the trailing edge of the wing, near the fuselage, that the pilot extends or retracts to change the wing's shape. When extended, flaps increase lift and drag at lower airspeeds, allowing the airplane to fly slower without stalling and to descend more steeply without gaining excess speed. They are typically used during takeoff, approach, and landing.
Plain English
Movable panels on the back edge of the wing, close to the body of the airplane, that the pilot lowers to help the airplane fly more slowly and come down at a steeper angle without speeding up. They are mainly used for takeoff and landing.
Context Anchor
You see this term in takeoff, landing, approach, and stall-practice discussions, especially when the airplane is being configured to fly slowly.
Derivation
‘Flap’ comes from Middle English ‘flappe,’ meaning something that hangs loose and can be moved up or down. The word fits well: a wing flap is a panel hinged to the back of the wing that the pilot can lower (or raise) to change how the wing behaves.
Why Pilots Care
Flaps reduce stall speed and allow steeper, slower approaches, shortening landing distance while keeping the airplane controllable.
Grounding Statement
Lowering wing flaps helps the airplane fly slower, but it also adds resistance that the pilot must manage.
Intuition Check
Do not think of wing flaps as loose parts that flap up and down. They are controlled wing panels moved by the pilot to change how the airplane flies.
Example Sentence 1
On final approach, the pilot extended the wing flaps to slow the airplane and steepen the descent toward the runway.
Example Sentence 2
During the power-off stall, full wing flaps were used to simulate a landing configuration and observe the resulting pitch change.