Originally Posted by
sophia1
can someone tell me why there is a difference in actual flight times.
AirCanada London UK to Calgary AB - flight time is 8:30
AirTransat London to Calgary - flight time 9:35
Both are direct flights, doesn't make sense to me.
It depends on the routing. Flights tend not to go in a straight (well, accounting for the curvature of the Earth) line, but point to point..and flight paths can be more of a zig-zag pattern and that can add time.
Other considerations are altitude and direction. Air is denser lower down, and that can mean slower speeds.
Direction of travel has an impact as well, although this doesn't apply to the flights you mentioned. In the northern hemisphere, westbound flights take longer because of the prevailing winds which go west to east. In the southern hemisphere the reverse happens, because winds tend to go east to west. A flight from LAX to YYZ may be 4.5 hours, but YYZ-LAX is 5.5 on average.
Other airlines may vary because of assigned fuel burn. They may slow down to maintain lower consumption so they don't have to refuel as much at the destination depending on where the aircraft is going next and what deals they got on fuel.