A look at AA's downloadable timetable reflects an interesting scheduling discrepancy that's carried across a number of flights. And I can't imagine any technical reasons that would explain it.
AA's MIA-CUN service, all nonstop, is listed in the timetable with the shortest flight (AA2157) at 39 minutes in duration. The longest flight from MIA-CUN (AA2185) is 49 minutes.
But the return route, CUN-MIA, again all nonstop, and operated with the same 72S and 738 equipment, shows a shortest trip length on AA2158 at 2h 31m, and a longest duration on AA2186 of 2h 40m.
Now, anyone knows the eastbound flights, all of which are scheduled for 2 hours longer than the westbound flights, are operated with the benefit of some west-east tailwinds...so why in the world are the CUN-MIA flights so much longer than the MIA-CUN flights?