The ruling gives Northwest the advantage in stalled talks with attendants, who hoped to gain leverage with the chance to strike the airline. They're balking at $195 million in annual pay and benefit cuts imposed as the carrier works toward a second-quarter bankruptcy exit.

Northwest enacted the cuts July 31 after the union for its 9,300 attendants rejected two contracts negotiated by their leaders. The savings are part of the Eagan, Minn.-based airline's $1.4 billion in annual reductions in labor spending.

Northwest said in a statement that it was pleased with the ruling and that it hoped to reach a consensual agreement with the Association of Flight Attendants-CWA.

The union was "very surprised" by the decision, spokesman Ricky Thornton said, and the group is considering whether to appeal.

The union wants the National Mediation Board that governs airline labor disputes to "release" it from talks with Northwest, triggering a 30-day countdown to a possible strike. The sides last met face to face Feb. 2, and no new talks are scheduled. The attendants are urging federal lawmakers to press the mediation board to grant the release.

Unlike Northwest's other unions, the attendants don't have a claim in the airline's bankruptcy. The group would have had a $182 million claim had it ratified a contract in 2006. Thornton said there is a risk the attendants will get nothing if they don't reach an agreement before Northwest exits bankruptcy.

In its ruling, the appeals court said the U.S. Railway Labor Act "forbids an immediate strike when a bankruptcy court approves a debtor carrier's rejection of a collective-bargaining agreement" that is subject to the act and allows imposition of new terms.

"For airline unions, this is a big setback," said John Gallagher, a lawyer for the Air Transport Association, the Washington-based trade group for major U.S. airlines.

Northwest filed for bankruptcy Sept. 14, 2005, the same day as larger rival Delta Air Lines Inc. Delta expects to exit bankruptcy by April 30.