You'll not be surprised that airlines chose the cheapest method available. Taxis and busses are often too expensive so airlines position their crews by air (at interline, service travel rates), rail, hire car and such like. But as a typical session is three to four hours long with a two hour brief and hour debrief we are talking about a whole day. That will often mean a crew will have to be put up in a hotel the night before. Unless of course you work for some LoCo's when you have you get yourself the sim, rested, on time and if you had better be there or...
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