Definition
The act of lowering the wing flaps from their stowed (retracted) position into a deflected position, increasing the wing's camber and, depending on the flap type and setting, its surface area. Flap extension increases lift and drag, allowing the airplane to fly safely at slower speeds and follow a steeper descent path without gaining excess airspeed.
Plain English
Lowering the flaps on the wings. This lets the airplane fly more slowly and come down more steeply without speeding up.
Context Anchor
You encounter flap extension when using the flap control during takeoff, approach, landing, and some training maneuvers.
Derivation
From the Latin extendere, meaning 'to stretch out.' The flaps are stretched out from the wing into the airflow, which fits the everyday sense of extending something outward from where it was stored.
Why Pilots Care
Proper flap extension allows safe low-speed flight and shorter landing distances while maintaining control; incorrect timing or degree can increase stall speed or create excessive drag.
Grounding Statement
When the pilot selects flaps, part of the trailing edge of the wing moves down and the airplane usually slows, lifts more at lower speed, and descends more readily.
Intuition Check
Flap extension does not mean adding an extra piece to the wing. It means moving the airplane’s existing flaps from retracted to a selected down position.
Example Sentence 1
On final approach, the pilot called for flap extension to 30 degrees to slow the airplane and steepen the descent.
Example Sentence 2
On short final the pilot completed full flap extension to achieve the target approach speed.