Partly to do with landing, taxiing fees. In the West they are considerably higher than at most airports in South East Asia

but on a return they have lo land at both places so surely the same taxes at both airports?

Enter the pilot, LOL. It could be supply and demand BUT it could be due to the jet stream. Planes simply have to buck that wind. For instance it might take as much as 2 hours longer on a long flight going East to West than in the other direction. We measure time in ground speed but the plane is limited to its airspeed. If it's going 500 mph into a 500 mph headwind its ground speed will be zero. It's going nowhere. OTOH in the other direction it would have a tailwind and would be going 500 mph airspeed and 1,000 mph, ground speed. Winds exaggerated for example, of course.

There is also the rotation of the earth. If you are on a 24 hour flight the earth will rotate once. Depending on whether the plane is flying with or against the earth's rotation, its ground speed will be faster or slower.

I've never been involved in assessing ticket prices but I do know that the cost of operating a plane is always expressed as X $ per hour.

I really have no idea if any of the above is figured into prices. I just know the phenomena exist.

Fun to think about, anyway.

Cheers.

The rotation of the earth has nothing to do with flight time, the earths atmosphere rotates with the planet, exit a post from a pilot.

Quite right ableguy. NeverSure, that's one thing you aren't sure of, and if they taught you that in flight training, you'd better ask for a refund.

On your explanation, if you're flying west, you'd never arrive, so better to fly east and avail yourself of the earth's rotation speed.

I understand that you've exaggerated the winds for your example, but I often had 250 knot/hr (400 Km/hr) tailwinds over Japan, above 37000 feet. That made for a ground speed of about 1300 km/hr, almost 22 kms/minute, or less than 3 secs per kilometre. That's flying!!! Not so good flying west though, and we were often down at 16,000 feet but still with 100 knots on the nose.

Fun exercise. Try to land on the carrier at sea.

http://www.montereyinstitute.org/noaa/lesson08/l8ex1.htm