Originally Posted by
spin88
The main point is that Delta, because it has many older, depreciated, planes, can adjust capacity in a way that UAL can not.
I don't believe the facts support that contention. Even ignoring the CO-origin aircraft (because of the way planespotters.net presents in-service dates), mainline UA has about 100 aircraft that are more than twenty years old. These covers a broad spectrum of passenger count and range: 747s, 757s, 767s, 777s, and A320s. There's plenty of planes fully-depreciated UA can park if it doesn't like average fares vs. variable expense.