FORT WORTH, Texas – American Airlines’ three largest unions announced Friday that they will support a potential takeover bid by US Airways Group Inc., posing another challenge for the Fort Worth-based airline as it tries to restructure in bankruptcy court.

The Allied Pilots Association, Association of Professional Flight Attendants and Transport Workers Union said they have also reached agreements on terms and conditions for collective bargaining agreements that would govern American employees in the event of a merger with the Arizona-based carrier.

The merged carrier would be called American Airlines and headquartered in Fort Worth, where AMR Corp., American’s parent company, currently has its main offices, the Allied Pilots Association said.

“As envisioned, a merger of US Airways and American Airlines provides the best path for all constituencies, including employees of both American Airlines and US Airways,” the three unions said in a joint statement. “The contemplated merger would be based on growth, preserve at least 6,200 American Airlines jobs that would be furloughed under the company’s standalone strategy, and provide employees of both American and US Airways with competitive, industry-standard compensation and benefits.”

In a letter sent to employees Friday, Doug Parker, chief executive at US Airways, called the agreement with the American unions “an important first step” toward a merger.

“Our intention would be to put our two complementary networks together, maintaining both airlines’ existing hubs and aircraft, and create an airline that could compete successfully with United, Delta and other carriers within our industry,” he said.

The news comes before the start of a Section 1113 hearing Monday in U.S. Bankruptcy Court in New York, where the company’s attorneys will try to persuade a judge to terminate the union contracts.

The unions have been in talks since February with American executives about $1.25 billion in proposed employee-related cuts, which include more than 14,000 layoffs, mostly of union members.

The airline maintains that the cost-cutting is necessary to fix its finances and allow it to compete with lower-cost competitors.

American spokesman Bruce Hicks said the agreement between the union and US Airways is “no coincidence given the timing of the 1113 process.”

“These statements do not in any way alter the company’s commitment to pursue our business plan or our focus on moving steadily through the court supervised restructuring process to create a profitable, growing industry leader,” Hicks said.

On Thursday, Fort Worth-based American reported a $1.7 billion first-quarter loss, mainly from restructuring costs related to bankruptcy. Excluding the one-time write-offs, the airline said it had a net loss of less than $300 million, smaller than the $436 million loss in the first quarter of 2011.