Definition
A high-lift device installed on the front edge of the wing that extends or droops downward to increase the wing's camber and lift at low airspeeds, particularly during takeoff and landing.
Plain English
A movable panel on the front of the wing that hinges down to help the wing produce more lift when the airplane is flying slowly.
Context Anchor
Seen in discussions of wing design, takeoff and landing performance, and high-lift devices.
Derivation
‘Leading edge’ is the front edge of the wing — the edge that meets the air first, or ‘leads’ into the airflow. ‘Flap’ comes from the older sense of a hinged piece that swings or folds. So the name simply describes a hinged panel at the front of the wing, distinguishing it from the more familiar trailing-edge flaps at the back.
Why Pilots Care
They reduce stall speed and improve low-speed handling, allowing safer takeoffs and landings in a wider range of conditions.
Intuition Check
Do not think of this as the same as the trailing-edge flaps commonly seen at the back of a wing. A leading-edge flap is on the front of the wing and changes how air first flows over the wing.
Example Sentence 1
On approach, the leading-edge flaps extended automatically as the airspeed slowed, helping the wing keep flying smoothly at a lower speed.
Example Sentence 2
During the preflight check, the instructor confirmed that the leading-edge flaps moved freely into position.