In a statement, the airlines said they were "pleased" that leadership of the US Airline Pilots Association had approved a memorandum of understanding on the matter.
AMR Chairman and Chief Executive Officer Tom Horton told employees Thursday a decision on a merger will be made "within a matter of weeks."
In the meantime, pilot and flight attendant unions are taking proactive measures in anticipation of a decision to proceed with a merger.
US Airlines pilots would have to vote on the memorandum of understanding its leadership approved.
The Allied Pilots Association, which manages affairs for American Airlines pilots, has already approved its own memorandum of understanding, The Dallas Morning News reported Saturday.
The Association of Professional Flight Attendants, which represents American flight crews, has also approved an outline to cover a merger with US Airlines.
Association of Flight Attendants-CWA, which represents US Airways flight attendants, said in a statement it was "watching these proceedings closely, and we will enforce our collective bargaining rights, seniority rights and any other rights in the event of a merger."