For the purposes of this Act:
(a) a flight of an aircraft commences:
(i) at the time of the closing of the last external door of the aircraft to be closed before the aircraft first moves for the purpose of taking off from any place; or
(ii) if subparagraph ( i) is not applicable--at the time at which the aircraft first moves for the purpose of taking off from any place; and
(b) a flight of an aircraft ends:
(i) at the time of the opening of the first external door of the aircraft to be opened after the aircraft comes to rest after its next landing after the commencement of the flight; or
(ii) if subparagraph ( i) is not applicable--at the time at which the aircraft comes to rest after its next landing after the commencement of the flight;
or, if the aircraft is destroyed, or the flight is abandoned, before either subparagraph ( i) or subparagraph ( ii) becomes applicable, at the time at which the aircraft is destroyed or the flight is abandoned, as the case may be.