I have not flown US Airways but the following might help.
There is a whole forum on http://www.flyertalk.com devoted to US Airways which will give lots of details.
If memory serves , Us Air fly from LGW via PIT or PHL with either the Airbus A330 or Boeing 767. ( Most people prefer the A330 as it as PTV's in all cabins including coach ( I think the B767) only has main screens)