Originally Posted by
irishguy28
Given that jetlag would be the main noticeable factor for longhaul journeys, this "2 hour variance" in expected time would only be observable for travellers moving within the same timezone, or one timezone difference either way.
And given that there are only 4 "major" countries in the Southern Hemisphere that use DST (Chile, Paraguay, parts of Australia, New Zealand) I don't think this "2 hour variance" is much of an issue for North-South (or vice versa) travellers; jetlag and tiredness from travel is going to be the dominant factor.
What has jetlag got to do with it? Flight schedules are impacted by the 2 hour variance between summer and winter. For example
BA16 21/10 scheduled to depart Sydney at 15:50 and arrive in Singapore at 21:05 ; depart at 22:35 and arrive into London at 05:05
BA16 28/10 is scheduled to depart Sydney at 16:30 and arrive in Singapore at 21:30 ; depart at 22:55 and arrive into London at 04:55
Even the 1 hour time difference between last week and this leads to a later departure out of Sydney by 40 mins and a 10 min earlier arrival time. I suspect that the start of DST in Australia earlier in month also had some impact
The airlines know when DST starts and ends in the different countries and plans schedules accordingly