Who else outsources -900's?
You're looking at aircraft type, rather than size, which really isn't relevant. United outsources large numbers of EMB-175s, which can seat up to 88 passengers. They just have them configured with fewer seats by installing first class, which is exactly what Delta does with the -900s in order to comply with DALPA's scope language. You also mention USAirways, who is allowed to outsource airplanes already with up to 86 seats. Those airplanes have been in the air for many years already with Mesa. Sorry, but you can't paint this as some sort of new paradigm. Outsourcing airplanes the size of -900s has been going on for quite some time. DALPA's TA is just putting better restrictions on it.