This might be a silly question but my thinking was the following:
There has to be a definition of time in an airplane for the logging of data and so on, but what definition would that be assuming a flight goes across timezones?
Would it be the local time at the airport of departure? Or at that of arrival? or maybe even a third, commonly agreed upon time (e.g., GMT)?
The idea came from a story of a friend that was traveling with the ship from Italy (GMT+1) to Greece (GMT+2). The cafeteria on board had a sign saying that it opens at 14:00, but on 14:20 local Italy time, while the ship was anchored in Italy, he was denied service by the crew saying that the sign was referring to Greece local time; where the ship "belongs".