Experts say the pilots' memorandum of understanding could be sign that a merger between American Airlines and US Airways is a strong possibility.
The pilot groups for both airlines on Tuesday released the memo, an interim agreement that details how both groups would work together in the event of a merger.
The union for American Airlines pilots, the Allied Pilots Association, approved the memo on Dec. 29, 2012. American and US Airways also signed off on the agreement.
Mark Ralston, an independent bankruptcy expert, said the agreement shows a lot of work between both union groups and the airlines.
He said it also hints of a strong desire to merge.
"If the AMR folks -- with the support of creditors -- didn't want to do this, they wouldn't be doing this," he said. "Maybe management isn't enthusiastic about it, but it appears AMR's creditors are interested in it."
APA spokesman Tom Hoban said the agreement represents what the group wants -- a merger.
"We want to see a merger while inside bankruptcy," he said. "We believe it's to the airlines' benefit, our passengers' benefits."
According to the memo of understanding, pilot groups would at first work separately, flying each airlines' aircraft as they do right now. A few years down the road, the seniority lists for each would be combined.
"It satisfies requirements of American Airlines management and US Airways management going forward," Hoban said.
"The terms of the M.O.U. currently are not effective and only become effective in the event a merger is approved and consummated," American Airlines spokesman Bruce Hicks said in a written statement.
Airline experts and bankruptcy experts agree that a lot more is most likely being hashed out, such as where the airline would be headquartered, routes and who would lead a combined airline.