OK, this is a weird one, and I wondered if anyone has any ideas.

I have noticed on my last few flights LHR-VIE return on Austrian, credited to my Aeroplan account, that for the LHR-VIE segment I am consistently getting 552 miles, while for the VIE-LHR segment I am getting 789 miles. I note one is exactly 70% of the other.

As far as I can determine, it isn't that the fare class is different on the different segments (always unrestricted economy).

Is Vienna really closer to London than London is to Vienna? Does the Aeroplan database really have two separate entries for the distance A-B and B-A, which can get out of sync? Any other ideas?

TM