But the airline's dense network of routes on the East Coast will provide BA with the steady feed of passengers it needs to compete with the giants United and American.
Alone among the big US airlines that have survived deregulation, USAir virtually ignored international travel, offering only token services to London and Frankfurt from its regional hubs.
Instead it prospered during the 1980s thanks to its domination of the short-hop business travel market in the US North-east, earning strong profits and expanding quickly without having to invest in jumbo jets, first-class service or expensive marketing.
It was also one of the last of the big airlines to join the acquisition binge of the era. It bought the successful regional Piedmont Aviation in the South, and Pacific Southwestern Airlines in California in 1987, integrating their route networks but largely failing to preserve the unique passenger service that had made them so popular.
The mergers, while eventually making USAir the country's fourth-largest carrier, also brought it into direct competition with the big national airlines.
It has since scaled back its West Coast service and is once again focused on the East Coast, where it has bought new landing slots at the National Airport in Washington and has taken over the operation of Donald Trump's Washington-New York-Boston shuttle service.
USAir - known as Allegheny Airlines until 1979 - was founded in 1939 as a dispatch service whose monoplanes were famous for dropping parcels in remote hill communities and snagging mail satchels off poles without landing.
The service made it the natural carrier for many smaller northeastern towns when passenger service was introduced later. For many years it was known - with various degrees of affection - as 'Agony Air' by regular business travellers.
In the 1990s USAir's focus on short domestic flights has made it vulnerable to the recession and to higher fuel prices, and it has been obliged to cut costs dramatically to survive where many competitors have failed.Reuse content