Originally Posted by
pandaperth
With AA SWUs - each one can be used to upgrade up to three AA-marketed and operated flights. They have to be heading in the same direction, more or less. So for instance one could upgrade HKG-DFW-MIA-LHR using one SWU, but not say LHR-LAX-MIA-GRU.
I believe the rule is that all stopovers must be in one direction. So LHR-LAX-MIA-GRU would be fine if LAX and MIA were transits. I've done similar before.
Likewise LHR-DFWx-GRU-LAX would be fine. Basically ignore the transits when working out if you are going in one direction or not.