Originally Posted by
ijgordon
And your ticket is a somewhat known loophole of LAX-SJU (or other Caribbean destinations) fares that AA has never decided to close.
Though they'll sometimes "close" it at random when they need an additional F seat, as reported and debated on this board.
OP probably could have gotten F on JFK-LAX for but a few bucks more had A inventory been available (though this is sporadic on JFK-LAX, unlike MIA-LAX which always seems to have it on the 777s).