Flight attendants for Northwest Airlines Corp. announced yesterday that they have begun a countdown to walk off the job, a day after rejecting a contract that would have cut their pay by about 20 percent.

The announcement is the latest in a battle between Northwest, which is struggling through bankruptcy reorganization, and its 9,300 flight attendants.

The employees, who are represented by the Association of Flight Attendants, said they were gearing up to take action as soon as 10 p.m. Aug. 15, the end of a 15-day warning period.

The union is not in negotiations with the airline, but an agreement that avoids job actions could still be reached before the Aug. 15 deadline.

Northwest filed a motion in bankruptcy court to prevent the flight attendants from striking or taking other job actions, said Roman Blahoski, an airline spokesman. He said the airline thinks such strikes would be illegal under the federal Railway Labor Act.

Blahoski said the airline was "not discussing contingency plans" but would be willing to sit down with the flight attendants. Any deal, he said, must include $195 million in savings that the airline is seeking from the attendants.

It is not clear how the attendants' actions will affect travelers. Experts urged fliers to choose other airlines or buy refundable tickets if the two sides do not reach an agreement.

The attendants, for now, do not plan on widespread strikes but intend to conduct what one industry observer called "guerrilla warfare."

Under a program known by the union as CHAOS (create havoc around our system), members will walk off certain planes, not show up for work or strike at specific airports.

"The members are very angry," said Mollie Reiley, president of the bargaining group for Northwest flight attendants. "To some of them, it's as basic as whether or not they can continue to work here. I think, for a lot of them, they had nothing to lose by rejecting it."

No specific plans have been put in place, and the union has been educating its members about potential actions, Reiley said.

Analysts said the attendants could harm Northwest by disrupting its operations and driving away business travelers. Northwest, which has 46 flights out of the Washington area's three major airports, filed for bankruptcy protection last year.

"Any disruption to service and the ability to deliver the service could be devastating," said Ivan Feinseth, an analyst with Matrix USA LLC.

A federal judge gave the airline permission two months ago to toss out the flight attendants' old contract if the two sides could not reach a new agreement.

On Monday, union negotiators presented the attendants with a proposal that would cut total salaries and benefits by $195 million. Despite being endorsed by union negotiators, that deal was rejected by the attendants in a 55 to 45 percent vote. The company quickly announced that it would begin imposing cost-cutting measures, which include a 21 percent reduction in pay for attendants.

Union officers said the company's proposal will cut the salary of a flight attendant with 10 years on the job from $41,000 to about $33,000.

The union says the new agreement will further reduce pay and benefits by allowing the airline to recalculate the way attendants are credited for flight hours.

Some travel experts are advising fliers to steer clear of Northwest in coming weeks.

Lisa Davis, editor of Frequent Flyer magazine, urged travelers to book flights on other carriers. If the flight is short, customers might be better off driving, she said.

Other experts said there was little that travelers can do because flights on other airlines are largely booked. Also, they said, flight attendants are going to engage in seemingly random job actions -- making it difficult for travelers to pick and chose what routes to avoid.

"It's like guerrilla warfare," said Mike McGarry, vice president of marketing and public relations for Short's Travel Management. "It will inconvenience a bunch of people and embarrass Northwest, but it won't shut down the system."