Plain English Meaning

Pulling the flaps back up into the wing after takeoff. The flaps were lowered to help the airplane lift off; once climbing safely, the pilot raises them again. Doing this too early or too abruptly can upset the airplane, especially when the pilot is flying only by instruments.

Full Definition

The action of moving the wing flaps from an extended position back to a retracted (stowed) position, reducing the wing's lift and drag and returning the wing to its clean configuration. During an instrument takeoff, premature or improperly timed flap retraction is a common error because it changes the airplane's pitch attitude and lift characteristics at a moment when the pilot is relying solely on instruments to maintain control.