Definition
A type of high-lift wing flap that extends rearward along tracks before deflecting downward. This motion increases both the wing's surface area and its curvature (camber), producing a large increase in lift with relatively little drag at the early stages of extension, and progressively more drag as it deflects further down for landing.
Plain English
A flap that first slides backward out of the wing to make the wing bigger, then tilts down to help the airplane fly slower for takeoff and landing.
Context Anchor
You may see this term in aircraft systems descriptions, preflight discussions, flap operation procedures, and takeoff or landing performance information.
Derivation
Named after Harlan D. Fowler, the American engineer who developed and patented this flap design in the 1920s. Knowing it is a person's name (not a description of the motion) prevents the reader from trying to decode 'Fowler' as a technical word.
Why Pilots Care
Enables slower approach and takeoff speeds while maintaining lift, shortening required runway length and improving safety margins.
Analogy
Think of pulling out a small shelf and then tilting it down. The surface becomes larger first, then changes angle to affect the airflow more strongly.
Intuition Check
Do not assume a Fowler flap is just any flap that hinges downward. Its key feature is that it slides rearward as part of its movement.
Example Sentence 1
On takeoff from a short field, the pilot selected 10 degrees of Fowler flap to gain extra lift without adding much drag.
Example Sentence 2
On final approach the Fowler flaps were lowered to allow a steeper descent at a safe airspeed.