Hundreds of United Airlines passengers were left temporarily stranded Monday when bad weather and a shortage of pilots led the world's largest carrier to cancel at least 242 flights nationwide.
The Chicago-based airline canceled about 500 flights during the weekend.
Among the flights canceled Monday were at least 15 out of Los Angeles International Airport and at least 25 out of San Francisco, said airline spokesman Matthew Triaca. United has major hubs in both cities. He could not say how many flights departing from smaller regional airports were affected.
Triaca said it was unclear whether the airline would cancel additional flights today. But the carrier urged travelers to check flight status before leaving for the airport.
Thunderstorms along the East Coast and in the central U.S. complicated by air traffic control constraints triggered the cancellations, Triaca said. Pilots calling in sick and declining to fly overtime also contributed to the scheduling problems, he said.
The airline, owned by UAL Corp., previously canceled as much as 2.5% of its flight schedule through September to account for the crew shortage, which arose after the company and its pilots union failed to reach agreement on a new contract in April. United typically flies 2,400 flights a day.
UAL shares rose 75 cents to close at $53.50 on the New York Stock Exchange.
UAL and the Air Line Pilots Assn., which represents 10,000 United pilots, have been negotiating a new contract since last year and asked for federal mediation of the talks in April.
Triaca said a contract was expected to be in place by Labor Day, but it remained unclear whether the airline would have to continue canceling flights this month. With many airlines flying near capacity during the torrid summer travel season, it might be difficult for United to switch its passengers to same-day flights run by other companies.
The carrier's operational problems became more complicated last month after aircraft maintenance workers caused more flights to be canceled. Those workers, represented by the biggest union at United, the Machinists, had expected their ongoing contract negotiations to lead to an agreement by last month.
United pilot Herb Hunter, a spokesman for the pilots' union, said he has sensed increased consumer disgust. Hunter was delayed heading toward Chicago on Saturday and walked back to the cabin to show passengers weather maps so they understood the wait had nothing to do with labor problems.
Hunter admitted that some United pilots have refused to work overtime but said there's no organized effort by the union.
Instead, he said the problems arose out of a shortage of pilots because the airline did not hire enough.
The airline responded that it is trying to hire 1,300 pilots by the end of the year.
The carrier said in an apology to customers late Monday that it's trying to improve operations by reaching a labor agreement with its pilots in the next three to four weeks and by tripling its spare aircraft, among other measures.
Bloomberg News and Associated Press were used in compiling this report.