"This is going to be an awkward, unwieldy beast from the management perspective," an executive at a rival carrier said.

Company executives have told analysts that about 15 percent of the calls over its network last June were actually on behalf of rival carriers.

And he said the rewards would come more easily than on rival carriers.

That could quickly reduce United's cushion of cash, according to the two executives at rival carriers.

So these days, most of the competition is to win over business travelers from rival carriers.

Along some routes, there are few rival carriers.

But the clause was written to count only increases at rival carriers, not decreases.

In the absence of new gates, rival carriers cannot enter monopolized markets.

But many industry analysts and executives at rival carriers dispute that.

But passengers could be in luck because rival carriers will apparently continue to honor American tickets for at least another day or two.