Unions representing the flight attendants of Southwest Airlines and AirTran Airways on Monday reached an agreement to work under one common contract once members ratify the terms, according to a joint statement by the attendants' respective unions.

Representatives of flight attendants from both airlines reached a Seniority Integration and Transition Agreement, condoned by SouthWest and AirTran, the statement said.

The Transport Workers Union Local 556 said it represents more than 10,000 Southwest flight attendants, while the Association of Flight Attendants Council 57 represents over 2,400 AirTrain attendants.

Southwest announced its plan to buy AirTran in Sept 2010, and closed the deal in May 2011.

(Reporting By Yinka Adegoke; Editing by Dan Grebler)