AA at PHX is senior as it is the former main Hub of America West Airlines. America West had its main hub in Phoenix and at one time a smaller hub in Vegas and it experimented with one in Columbus Ohio in the 90's. America West merged with US Airways in 2005, and then there was the US AA merger in 2014. The folks there in PHX are well settled in that community and don't want to move so it is likely to stay senior for a while, at least another decade.