In Flight Law and Legal Definition
The term "in flight" is defined by 18 USCS § 31 as-
(A) any time from the moment at which all the external doors of an aircraft are closed following embarkation until the moment when any such door is opened for disembarkation; and
(B) in the case of a forced landing, until competent authorities take over the responsibility for the aircraft and the persons and property on board.