You're probably correct. I would still like to know how they work it out. I do it by normalising departure and arrival times to the same time zone so departing HKG at 1110 is equivalent to 0210 AMS time. Arrival time is 1640 (at AMS) so that means a flight time of 1640 - 0210 = 14h30m. Someone tell me I'm not going mad!