Answer:

UNBELT

Answer	Crossword Clue
UNBELT	Prepare to leave one's plane seat
UNBELT	Loosen
UNBELT	Remove the cincture.

UNBELT	Loosen, as a garment
UNBELT	Prepare to deplane
UNBELT	Release, in a way
UNBELT	Begin disrobing, possibly
UNBELT	Start to take off one's pants, say
UNBELT	Thing to do when leaving a car