Originally Posted by
nystateofmind
MCO I believe is cabin crew only. Other hubs only have bases for certain equipment. So while SEA has a base, I am not sure if A320 series is one of them so if an A319 pilot times out they would have to bring in one from an A320 base.
A319/320/321 pilots can and do fly any of the models, they are not exclusive. Similarly 757/767 pilots fly both models, the exception being the 767-400 which at Delta is a separate pilot category. At United however 757/767-300/400 models are all flown under the same category.