WASHINGTON – Mechanics struck Northwest Airlines early Saturday 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 Friday, 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 4,427 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, told reporters here that the airline will operate a full schedule on Saturday.

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 Friday.

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

In May, AMFA mechanics at bankrupt United Airlines threatened to strike if a judge imposed pay cuts. Instead, mechanics approved a contract that included a 3.9 percent pay cut and fewer benefits.

Northwest sought $1.1 billion worth of annual cuts from its employees. Last fall, pilots agreed to a 15 percent pay cut worth $300 million when combined with cuts for salaried employees. The pay cut sought for mechanics amounted to about 25 percent.

The carrier has some of the highest labor costs in the industry. And older airlines have been battered by rising oil prices and travelers’ shifts to discount carriers.

Northwest employs 4,427 mechanics, cleaners and custodians represented by AMFA – down from 8,390 in January 2002. Of its current AMFA workers, 3,118 work in the Twin Cities, 964 work in Detroit, and 120 work in Memphis.

And the airline has taken advantage of a contract provision that allows it to send as much as 38 percent of its aircraft maintenance to outside contractors.

As the deadline drew nearer, dozens of mechanics and their family members gathered in a parking lot near the union’s regional headquarters in Bloomington. Within sight of a Northwest maintenance hangar, they grilled hot dogs, drank beer and waited for news.

“I’m afraid they’re going to try their best to break our union,” said Joe Woods of Atlanta, a Northwest mechanic for 23 years. “If they want to fight, this is a good place to start one.”

Ground workers didn’t say whether they would honor a picket line, but they had been considered unlikely to. Relations between the mechanics union and the ground workers union – the International Association of Machinist and Aerospace Workers – have been poor since 1998, when AMFA took over representation of mechanics from the Machinists.

On Friday afternoon, a federal judge barred mechanics at Northwest regional carrier Mesaba Airlines from staging a sympathy strike. Those mechanics are represented by the same AMFA locals that represent Northwest mechanics at hubs in Minneapolis, Detroit and Memphis.