Definition
A leading-edge high-lift device, mounted on the front of the wing, that can extend forward and down to open a slot between itself and the wing. When deployed, it allows the wing to produce lift at higher angles of attack and lower airspeeds, delaying the stall. Movable slats can be operated automatically by aerodynamic forces or actuated by the pilot or flight control system, in contrast to fixed slats which are permanently in place.
Plain English
A small panel on the front edge of the wing that can slide out to help the wing keep flying smoothly at slow speeds and steep nose-up angles. Because it moves, it can be tucked away when not needed and extended when it is.
Context Anchor
Seen in discussions of wing design, slow flight, stalls, takeoffs, landings, and preflight checks on airplanes equipped with slats.
Derivation
Slat comes from an old word meaning a thin strip or slab. Movable simply means it can change position. Together: a thin strip on the wing's leading edge that can move in and out as needed.
Why Pilots Care
Movable slats let the airplane fly safely at lower speeds during takeoff and landing without stalling.
Grounding Statement
At slow speed, a movable slat helps guide air over the wing so the wing can keep lifting instead of losing smooth airflow too soon.
Intuition Check
A movable slat is not the same as a flap on the back of the wing. It is on the front edge of the wing and helps control airflow before it reaches the main wing surface.
Example Sentence 1
As the airplane slowed on final approach, the movable slats extended automatically, helping the wing stay effective at the higher angle of attack.
Example Sentence 2
Movable slats on the wing helped keep airflow attached during a slow turn in the traffic pattern.