TULSA, Okla. (AP) — Mechanics and stock clerks at bankrupt American Airlines approved new labor contracts Wednesday, but union officials conceded that the vote won't prevent hundreds of workers at the airline's Tulsa maintenance hub from being laid off.

The Transport Workers Union said its mechanics group voted in favor of the new contract, which comes with 3 percent raises, by a razor-thin margin of 50.25 percent to 49.75 percent. The maintenance stock clerks voted 79 percent to 21 percent to accept their contract with a 3.5 percent wage increase.

After months of negotiations, the mechanics and clerks join five other TWU units that reached deals with the beleaguered airline in May: fleet service clerks, dispatchers, ground school instructors, maintenance control technicians and simulator technicians. If a federal bankruptcy court approves the new labor agreements, layoffs could begin within a few months.

About 900 workers could be cut in Tulsa, according to one estimate from the airline, compared with 2,100 lost jobs had the union employees voted the contract proposal down.

American Airlines, which has about 73,000 employees worldwide, filed for bankruptcy protection in November and announced a plan in February to eliminate thousands of union jobs as part of a cost-cutting move, including hundreds in Tulsa.

The airline is Tulsa's largest private employer, with about 7,000 workers, and has operated in the city for more than six decades. Union leaders have called the Tulsa hub "the largest concentration of middle-class jobs in Oklahoma," with the average employee making about $50,000 a year, similar to the city's other main industry of oil.

City leaders and union officials feared that if the worst of the cuts went through, the void would create an economic collapse similar to one that hit Tulsa during the 1980s oil bust. But whatever the total, the layoffs are a blow to the region's burgeoning aviation industry, which employs about 20,000 people. The president of the Tulsa Metro Chamber said Wednesday that the organization and its partners would be ready to help any displaced workers.

The union's president, James C. Little, said he was frustrated with the bankruptcy process but admitted there would be far worse alternatives if a bankruptcy judge throws out the current contracts American has with its workers.

"Our goal has been to maintain our options and lessen the impact on our members, and these agreements are part of that process," Little said in a statement Wednesday. "Nobody is happy with a concessionary agreement ... but this result is a lot better than what our members would have faced with a court-imposed solution."

American Airlines spokesman Bruce Hicks said the tentative contract agreements marked an important step forward in the restructuring of the company, whose parent, AMR Corp. of Fort Worth, Texas, is working through bankruptcy court after losing $11 billion since 2001.

"With today's news, we now have ratified agreements with all seven TWU-represented workgroups representing approximately 24,000 employees, which is meaningful progress in moving forward together as we build the new American," Hicks said.