Southwest Airlines and its pilots’ union have reached a new preliminary labor agreement, ending months of tense negotiations and becoming the last of the largest U.S. airlines to strike a deal that is set to give aviators big raises.

The five-year deal is worth about $12 billion, Casey Murray, president of the Southwest Airlines Pilots Association, told CNBC on Tuesday. The union didn’t immediately provide details about pilot pay increases.

The company’s pilots will need to approve the preliminary contract. CNBC reported earlier this month that the two sides were close to a deal.

American, United and Delta pilots finalized deals earlier this year that were worth billions and gave aviators double-digit pay hikes. The Covid-19 pandemic derailed negotiations across the industry.

As travel demand snapped back, pilots, flight attendants and other aviation workers have pushed for not just higher pay, but also better working conditions such as more predictable schedules.

Labor unions have flexed their power throughout the year, yielding a string of big labor deals including agreements between Hollywood studios and actors, and the studios and writers, as well as between automakers and the United Auto Workers union. Those agreements followed prolonged strikes.