Sch 15 para 1
(1) A person is within this paragraph if he is in one of Her Majesty's aircraft in flight. (2) For the purposes of sub-paragraph (1) the period during which an aircraft is in flight includes— (a) any period from the moment when power is applied for the purpose of the aircraft taking off on a flight until the moment when the landing run (if any) at the termination of that flight ends; (b) any period when the aircraft is on the surface of the sea or navigable waters. (3) In sub-paragraph (2)(a) a “ flight ” means a journey by air beginning when the aircraft takes off and ending when it next lands. (4) In this paragraph “ Her Majesty's aircraft ” means all aircraft belonging to or used for the purposes of any of Her Majesty's forces.