Article 2
For the purposes of this Convention:
(a) an aircraft is considered to be in flight at any time from
the moment when all its external doors are closed following
embarkation until the moment when any such door is opened for
disembarkation; in the case of a forced landing, the flight shall be
deemed to continue until the competent authorities take over the
responsibility for the aircraft and for persons and property on
board;
(b) an aircraft is considered to be in service from the
beginning of the preflight preparation of the aircraft by ground
personnel or by the crew for a specific flight until twenty-four
hours after any landing; the period of service shall, in any event,
extend for the entire period during which the aircraft is in flight as
defined in paragraph (a) of this Article.