A fare increase initiated last week by UAL's United Airlines was matched by competitors over the weekend, marking the second successful fare increase in two weeks.
United Airlines had said on Friday that it raised domestic U.S. air fares between $2 and $5 each way.
Major carriers, including AMR's American Airlines and Delta Air Lines , matched the increase over the weekend systemwide. In select markets, some carriers rolled back the increases as part of a typical pattern of competitive jockeying, according to air fare tracker FareCompare.com.
The latest fare increase comes just a week after Delta initiated a $5 increase each way in domestic U.S. fares, meaning some customers could be paying as much as $20 more for a round-trip ticket than they did two weeks ago.
The recent fare increase follows several failed attempts to raise fares over the past few months, as rival carriers failed to match pricing changes amid softening demand.
Airlines, which are flying with planes near record capacity, have been under fire in recent weeks for poor service after suffering from gaffes that have frustrated passengers.
Northwest Airlines , for instance, over the past two weeks canceled more than 500 flights because of bad weather and a shortage of pilots. The company Friday said it planned to cancel some flights in July and August in order to free up pilots.
Full planes leave airlines and passengers vulnerable to disruptions, because there are generally few seats available to travelers bumped from earlier flights.
"At these capacity levels, the smallest of glitch is magnified 10-fold because there is nowhere to put those that are stranded," said FareCompare CEO Rick Seaney. "Consumer frustration has definitely gone from bad to worse."
Higher ticket prices could dissuade some people from traveling, which in turn could help airlines reduce the strain on their systems.