US Airways had a great little fare rule built in. No only were co-terminals seen as the same with fare construction, they were also seen as the same for standby and the move-up policy. (Co-terminals are airports that are near each other and seen as virtually the same place.)
Basically, if you wanted to get on an earlier flight when flying to DCA, you could request an earlier flight that goes into Dulles and vice versa.
I live halfway between DCA and Dulles, so this was great. It increased my options if I got to an airport early and my priority is always getting home sooner once I’ve started travel.
But this policy just got merger-ed.
My red-eye from Seattle landed early, so I hopped over to a counter hoping to get on an earlier flight rather than take my later flight to Dulles. The gate agent let me know that the only earlier flight is to DCA, and that US has recently removed the ability to switch to a different terminal in the same area.
It was nice while it lasted. I believe (correct me if I’m wrong) this makes their policy similar to the other major airlines.
I don’t believe this would affect situations with irregular operations. When I’ve had irregular ops, I’ve been allowed to move to airports that aren’t even considered co-terminal (I was allowed to fly into Baltimore during a huge snow storm, for example).
But switching airports last minute is no longer on the table.