Originally Posted by
Often1
This is a purely AA question because BA will relinquish control 24 hours prior to UK departure.
On arrival at MIA, head over to AA and have them pull up your AA PNR (it will not be the same as BA) and make certain that AA shows you as being on an A fare.
AA will reassign you to F (it is not an upgrade as you have an A ticket) if there is A space. If not, you would only then be upgraded based on AA status.
Don't get your hopes up as last second A space is fairly uncommon.
I think the odds are better if the OP can fix this in advance with BA's help as I'm not convinced that AA will see anything but a Y booking class when OP gets to MIA unless there's a lot of integration between the AA and BA systems.
IIRC there have been reports of similar situations with award tickets where the person paid miles for FC but was booked in coach because there was no FC (saver) award inventory. It couldn't be fixed at the airport because the receiving carrier just saw a coach award ticket and coach booking class.
BTW, OP refers to a FC fare, so I'm assuming that this isn't an award ticket but rather a discounted FC ticket paid with money.