I've read this question about whether one should fast in case of long distance travelling.
Nevertheless a case that is not mentioned in the answer is what happens if one is travelling between different time zones. Not that much the time zones are the issue, but more the fact that the sun is shining at different time intervals at the different locations.
Say for instance you travel from New York to London. If the plane takes of at 8 AM local time, then the plane arrives in London at 8 PM local time. But it took the plane only 7 hours to do that. As a result one has "virtually" shortened the day. The opposite can also happen: a plane from London to New York virtually makes the day longer.
My question is what should happen to the fasting hours in that case. Should one use the local ones (and thus fast longer on a day one travels from London to New York), or should one stick to the context of the begin/end of the voyage?