Originally Posted by christep
It's a standard benefit - no problem joining the F/J boarding line as an Emerald in Y. (The only caveat being if, for example, the Y cabin is not yet available for boarding due to, say, cleaning - I have seen this once...)
Normal boarding for AA EXP (Emerald) and PLT (Sapphire) flying AA is after F/J, but before Y. AA Gold (Ruby) boards with Y Group 1.