Definition
The act of extending the wing flaps from their retracted position into a lowered position, increasing the wing's camber and, depending on flap type and setting, its surface area. Flap deployment increases lift and drag, allowing the airplane to fly safely at slower speeds and descend at steeper angles without gaining excess airspeed.
Plain English
Lowering the flaps on the wings. This changes the wing's shape so the airplane can fly more slowly and come down more steeply, which is useful for takeoff and especially for landing.
Context Anchor
You will see this term in procedures for takeoff, approach, landing, and go-around, especially where the handbook explains when to extend flaps and at what speed.
Derivation
Deploy comes from the Old French desploiier, meaning 'to unfold or spread out.' That fits well here: the flaps are tucked into the wing when not needed and are unfolded into the airflow when the pilot wants more lift and drag.
Why Pilots Care
Proper flap deployment allows lower approach speeds and shorter landing distances while maintaining control, but incorrect use can increase stall risk or extend landing roll beyond available runway.
Grounding Statement
Picture the flaps tucked into the back of the wing, then moving down and back into the airflow as the pilot selects them.
Intuition Check
Flap deployment does not mean the airplane has flaps installed. It means the flaps are actually extended to a selected position for use.
Example Sentence 1
On final approach, the pilot completed full flap deployment to slow the airplane and steepen the descent toward the runway.
Example Sentence 2
Full flap deployment helped reduce the landing distance on the short grass runway.