Definition
The minimum airspeed at which the wing flaps can be safely raised after takeoff without the airplane settling, sinking, or losing the lift margin needed for continued climb. It is published in the Airplane Flight Manual or Pilot's Operating Handbook and is reached during the initial climb before the pilot begins retracting flaps from the takeoff setting.
Plain English
The speed you need to reach in the climb before it is safe to raise the flaps. Below this speed, pulling the flaps up can cause the airplane to sink or lose climb performance.
Context Anchor
Seen in takeoff, initial climb, and go-around procedures, usually in the Pilot’s Operating Handbook, approved flight manual, or checklist.
Derivation
“Retract” comes from Latin roots meaning “to draw back.” In this term, it points to drawing the flaps back from an extended position; the speed tells the pilot when that action should happen.
Why Pilots Care
Retracting flaps too soon can produce an abrupt drop in lift and a stall; delaying retraction keeps unnecessary drag and limits climb performance and obstacle clearance.
Intuition Check
Flap retraction speed is not how fast the flaps physically move. It is the airplane’s speed at which the pilot should begin or complete bringing the flaps up according to the procedure for that airplane.
Example Sentence 1
Once established in the climb and passing flap retraction speed, the pilot raised the flaps in stages.
Example Sentence 2
For this airplane the published flap retraction speed is 10 knots above the takeoff-configuration stall speed.