American Airlines is tinkering with its bid for new service to China, proposing that flights from Dallas stop in Chicago en route to Beijing, to get around objections from pilots. The airline said Friday it has asked to amend its plan now pending before the U.S. Transportation Department.

Return flights would operate directly from Beijing to Dallas because tail winds reduce their time, the airline said.

American, the nation's largest airline, and three other carriers submitted proposals in October for seven new weekly round-trip slots between the United States and China.

American said it was changing is proposal because nonstop Dallas-Beijing westbound flights are 15 minutes longer than allowed under the airline's contract with its pilots. The company and the pilots' union have failed to reach a side deal that would allow longer flights to China.

The Chicago-Beijing leg would squeeze in under the current rules. American would change crews in Chicago to comply with limits on pilots' work days, spokesman Charley Wilson said.

For passengers who board in Dallas, however, the flight to Chicago and a stopover at O'Hare Airport would add about four hours to their trip.

Wilson said the change in the company's proposal was unprecedented in the airline industry. He said American didn't know how it would affect its chances of winning the route.

Officials with the Allied Pilots Association didn't return calls for comment, but the union issued a statement supporting the changed proposal. "Expanding American Airlines' international reach is in the long-term best interests of our airline, its employees and our passengers," the union said.

Last month, the union conditioned its support on concessions including pay for canceled flights. The company answered that the union request should be part of regular contract negotiations, which are likely to last into 2008.

American had based its proposal on becoming the first airline to serve China from a Southern state. The mayors of Dallas and Fort Worth and officials at DFW Airport said they supported the stopover in Chicago, saying the service would still benefit Texas and other states.

United plans to fly from Washington to Beijing, Northwest wants to add service from Detroit to Shanghai, and Houston-based Continental proposes to fly from Newark, N.J., to Shanghai.

Michael Boyd, an aviation consultant who has worked recently for both American and the union, said United will probably win the competition because it would link the two capitals. Still, he faulted American for changing its plan, which highlighted tense labor-management relations.

"This one was dead in the water anyway, but everybody should have kept their mouths shut about any arguments in the cockpit," he said.

Leaders of the pilots' union have been angry at the company since early this year, when it gave bonuses to about 1,000 executives and managers, with a few topping $1 million. Pilots are still living under wage concessions they approved in 2003, when American was near bankruptcy.

Northwest asked the Transportation Department to disqualify American from the competition for making a "radical change" after the bidding deadline. United said American's new route would be "even more inconvenient" for customers.

Each of the airlines competing for the China routes has recruited politicians and the flying public to woo the Transportation Department.

Northwest gathered 168,000 letters of support, while United lined up 110 congressional backers and hired the nation's former top aviation regulator to lead its campaign. American, a unit of Fort Worth-based AMR Corp., said 108 members of Congress and 15 governors supported its bid.