WASHINGTON — Mechanics struck Northwest Airlines early today after refusing big pay cuts and layoffs that would have cut their numbers almost in half. The nation's fourth-largest airline pledged to keep flying with replacements.

After months of talks broke off here just before midnight yesterday, union spokesman Jim Young said the mechanics would rather see the airline go into bankruptcy than agree to Northwest's terms. The Airline Mechanics Fraternal Association represents about 11 percent of Northwest's 40,000 workers. The strike began at 12:01 a.m. EDT.

Flight attendants and pilots at Northwest Airlines said they would not join the walkout by mechanics.

Julie Hagen Showers, Northwest's vice president for labor relations, said that the airline will operate a full schedule today.

Young said the company did not negotiate in good faith because it had a contingency plan to use contract workers as replacements for the strikers.

AMFA national director O.V. Delle-Femine said in a statement that the union expects flight schedules to be disrupted "because 4,500 AMFA technicians who average 20 years of live experience on Northwest's fleet are being replaced by 1,500 people who in many cases have little or no live experience on the type of aircraft Northwest flies." He said their training was "woefully inadequate."

Showers said the company's final offer was fair and equitable. The airline wanted to get $176 million in savings from the union.

"AMFA was unable to meet the saving targets we needed," she said. "It would have been irresponsible not to have a plan in place." Showers said the contingency plan would realize the desired savings.

At the union's headquarters in the Minneapolis suburb of Bloomington, Steve MacFarlane, assistant national director of AMFA, said the union had "no choice."

"Truly, we are fighting for our very futures and our families," MacFarlane said.

Among other unions at Northwest, only flight attendants had appeared to seriously consider a sympathy strike. Their own strike vote ended at midnight yesterday.

Over the past year and a half, Northwest has lined up about 1,200 replacement workers, plus 400 vendor employees and 300 to 350 managers for a total replacement force of 1,900. And it shifted to its slightly smaller fall schedule earlier than usual.

It's the first major airline strike since Northwest pilots grounded the airline for 20 days in 1998. AMFA has struck only four times in its history, most recently in 1980.
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All Northwest Airlines flights departing Honolulu for the Mainland last night were scheduled to leave on time, a reservation agent for the airline said. To check the status of flights, Northwest customers can call the airline at (800) 225-2525, or visit its Web site, www.nwa .com.

Northwest flew 324 flights to Hawai'i last month with a total of 104,382 seats, state tourism liaison Marsha Wienert said. Northwest's share accounted for about 11 percent of the market, she said.