United Airlines pilots, represented by the Air Line Pilots Association, reached a deal in principle with the airline, giving the pilots up to a 40% raise, the union confirmed to CNN Saturday.

The deal has about $10 billion in value over the life of the contract, the union said, with improvements to "quality of work-life, compensation, job security, work rules, retirement, benefits."

The agreewment ends something of a long-term stalemate between the parties: The pilots and United management have been negotiating for more than four years, the union said.

As the post-pandemic travel boom ramps up, more pilot union groups are demanding improved benefits. Delta pilots approved a contract in March, which included about a 34% increase in pay. American Airlines pilots will also be voting on a contract.

The new United deal has cumulative pay increases that ranges from 34.5% to 40.2% based on the type of aircraft a pilot flies, the union said.

"We promised our world-class pilots the industry-leading contract they deserve, and we're pleased to have reached an agreement with ALPA on it," United Airlines said in a statement. "The four-year agreement, once ratified, will deliver a meaningful pay raise and quality of life improvements for our pilots while putting the airline on track to achieve the incredible potential of our United Next strategy."

After negotiators complete the final language, the agreement will have to be ratified by the 16,000 member pilots.