Article 4
For the purposes of article 3(a) an aircraft is not to be taken as carrying, for hire or reward, any passengers by reason only that:
(a)
it is carrying employees of the operator of the aircraft or of an associated company of the operator; or
(b)
it is carrying attendants who are travelling with its cargo or are on a return flight having attended cargo on their previous flight;and for the purposes of article 3(b) an aircraft is engaged on non-scheduled air transport services if the flight on which it is engaged is not part of a series of journeys between the same two places amounting to a systematic service.