Definition
A movable hinged surface on the trailing edge of the wing, near the fuselage, that can be extended downward to increase lift and drag at lower airspeeds. Flaps are typically used during takeoff and landing to allow the aircraft to fly safely at slower speeds and to descend at a steeper angle without gaining excess airspeed.
Plain English
A panel on the back edge of the wing, close to the body of the airplane, that the pilot lowers to help the airplane fly slower and come down more steeply during takeoff and landing.
Context Anchor
Seen in wing component diagrams, preflight inspections, cockpit flap controls, and takeoff or landing checklists.
Derivation
‘Flap’ comes from Middle English ‘flappe,’ meaning something that hangs loose and moves. The word fits because the surface hangs from the back of the wing and swings down when extended.
Why Pilots Care
Wing flaps let pilots maintain lift at lower airspeeds, shortening takeoff rolls and allowing safer, slower approaches and landings.
Intuition Check
A wing flap is not just any loose or moving piece on the wing. In this context, it is a specific movable panel used to change how the wing performs, especially at slower speeds.
Example Sentence 1
On final approach, the pilot extended the wing flaps to slow the aircraft and steepen the descent toward the runway.
Example Sentence 2
On final approach the pilot selected full wing flaps to increase drag and steepen the descent angle without increasing airspeed.