United Blames Canceled Flights on Pilots

United Airlines canceled at least 120 flights at O’Hare International Airport on Sunday, and the nation’s largest carrier blamed the cancellations on pilots who have refused to worked overtime since their contract expired in April.

On Saturday, 150 flights at O’Hare, more than 15% of the 960 daily flights in and out of Chicago, were scrapped for the same reason.

It was not immediately known how many, if any, of those canceled flights were bound for Los Angeles International Airport. However, LAX spokesman Tom Winfrey said there were no problems reported at United’s terminal Sunday.

United operates 2,500 flights a day.

A line of thunderstorms in the central United States on Sunday evening also created delays of up to two hours in Chicago, said city Aviation Department spokeswoman Monique Bond.

United spokesman Chris Brathwaite said many of the pilots had worked all their allotted weekly hours trying to make up for flights canceled Thursday and Friday because of bad weather in the East.

Since spring, United has had to cancel or delay flights because of pilot shortages, and Brathwaite couldn’t say when the continuing problem would be resolved.

August is the busiest air travel month, with most major carriers reporting flights more than 75% full.

United and the pilots’ union are negotiating a contract with a federal mediator and hope to have a new agreement in place by early September.

A spokesman for the union, the Air Line Pilots Assn., did not immediately return a call for comment. In the past, the union has denied there is an organized effort to refuse overtime work. The union represents 11,000 United pilots.