The Southwest Airlines pilots' union says that it has signed agreements with Southwest, AirTran and the AirTran pilots' union allowing them to discuss seniority before Southwest finalizes its purchase of AirTran. Southwest said that the discussions were an important move towards fully combining the airlines. The purchase is expected to close in the next two months, when federal regulators approve it. The agreement between the two unions says that if they are not able to reach a deal on seniority, it will move to arbitration.
See "Southwest, AirTran pilots agree to talk seniority", Business Week, April 14, 2011