The leadership of the pilots union at AirTran Airways voted against the seniority integration agreements in AirTran's merger with Southwest Airlines, sending the unions back to the negotiating table to try to reach a deal.

The move comes as Southwest seeks to move ahead with its integration of AirTran after closing the acquisition in May.

The leadership of Southwest's pilots union in late July unanimously approved the seniority deal to send to its members for a vote, but the master executive council of the Air Line Pilots Association at AirTran on Thursday voted against the integration agreements presented by their merger committee. Thus, the leadership is not sending them to their members for a vote and canceled road shows scheduled this week on the agreements. Seniority is a key issue for pilots and can affect their schedules, pay and career expectations.

"It appears ALPA decided to deny both pilot groups the right to vote and decide on their future by keeping it from their membership ratification effort," Southwest Airlines Pilots' Association spokesman Jacob North said.

That leaves the two pilots unions to go into mediation through Sept. 30. If a deal can't be reached through mediated talks, the unions would then go to arbitration, according to the process the two unions agreed on.