DALLAS (AP) — Southwest Airlines has reached a tentative agreement on a new contract with union flight attendants, who have lagged behind pilots in winning pay raises from U.S. carriers.

Details were not released Wednesday about the deal, covering about 20,000 attendants at the Dallas-based airline.

The Southwest attendants rejected a previous deal in December that would have given them an immediate raise of 20% followed by four annual raises of 3%.

The attendants are represented by Transport Workers Union Local 556, which will hold a ratification vote. The union’s executive board approved the deal.

The union’s president, Lyn Montgomery, said the union will detail the agreement to members in meetings starting Monday and voting will begin in a few weeks.

Southwest’s vice president of labor relations, Adam Carlisle, said the attendants play a role in safety and passenger service. “I am glad they will have the opportunity to vote on this new agreement,” he said.

Pilots at American, Delta, United and Southwest all approved contracts last year that will raise pay about 40% over five years, but attendants have been unable to reach agreements. Delta Air Lines cabin workers are nonunion and do not bargain over pay and benefits.

The major airlines set records for quarterly revenue last year, as travel rebounded strongly from the pandemic.