This might be for historic reasons, or possibly to avoid confusion with a call sign used by an established airline.

As for the established airlines being cheaper, I never find that to be the case, though I do always check.

People Express itself started having financial difficulties from its own expansion and difficulty competing with established major airlines.

Yet the competitive turmoil in the industry has also made leasing more attractive to established airlines.

Competition has increased in recent years, as new low-cost carriers entered the market, undercutting prices set by more established airlines.

But lately, the established airlines have been offering some fares almost as low as Ryanair's.

Antics can be particularly effective for grabbing free publicity these days, when so many established airlines are cutting back on service.

After initially attempting to match the challengers, the established airlines stumbled on yield management.

Thirdly, we should discuss the established airlines' legitimate interests.

Southwest offered dramatically lower air fares than established airlines that usually enjoyed a near-monopoly in the communities.