Negotiators for pilots at Southwest Airlines have reached an agreement in principal with the company for a new contract, the union said Tuesday, adding that the union’s board still needs to decide whether to send the deal to members for a ratification vote.

The Southwest Airlines Pilots Association (SWAPA), which represents more than 10,000 pilots at the Dallas-based carrier, did not provide the details of the deal.

Casey Murray, SWAPA’s president, said the union’s board will meet on Wednesday to evaluate the deal and decide whether to send it to the pilots for a ratification vote.

Southwest and its pilots have been in negotiations for a new contract for more than three years and in federal mediation since September 2022.

The last contract became amendable in 2020.

Southwest pilots have been demanding higher pay and better work rules.

Union officials said a delay in the new contract has driven up attrition rates at the carrier, with hundreds of pilots leaving for rival airlines.

An industrywide shortage of pilots has left U.S. airlines scrambling to hire and retain talent, bolstering the bargaining power of aviators.

Pilots at United Airlines, Delta Air Lines and American Airlines have all secured hefty pay raises and improvements in working conditions in new contracts.

Post-pandemic labor shortages and high inflation have emboldened workers and their unions to use strikes, strategic walkouts and pickets to extract concessions across auto, airline, entertainment and healthcare industries.