United Airlines and the union representing its pilots said Saturday they reached agreement on a contract that will raise pilot pay by up to 40% over four years.

The union valued the agreement at about $10 billion. It followed more than four years of tumultuous bargaining that included picketing and talk of a strike vote.

The deal reflects the leverage enjoyed by labor groups, especially pilots, as airline revenue soars on the strong recovery in travel.

The Air Line Pilots Association said the agreement, which is subject to a ratification vote, would put United pilots on par with counterparts at Delta Air Lines, who approved a pay-raising deal earlier this year.

The union said the agreement includes substantial increases in pay, retirement benefits and job security.

At least on pay, the deal appears far better than one that United pilots rejected last November.

Once the deal is approved, pilots will get immediate wage-rate increases of 13.8% to 18.7%, depending on the type of plane they fly, followed by four smaller annual raises, according to a summary on the union’s website.

Over the course of the contract, pilot pay would rise 34.5% to 40.2%.

Garth Thompson, chair of the United pilots’ union, called it an “historic agreement” that was made possible by the resolve of the 16,000 pilots.

In a statement on the LinkedIn social media site, CEO Scott Kirby 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.”

Pilots at American Airlines are scheduled to begin voting July 24 on an offer that includes average cumulative raises of 41.5% over four years. Southwest Airlines pilots are still negotiating. American and Southwest have independent unions, while pilots at Delta and United are represented by ALPA.

The unions believe they are in strong bargaining position with airlines, which took $54 billion in federal aid to help get through the pandemic, booming because of a resurgence in travel. The number of people flying in the U.S. is roughly back to pre-pandemic levels.

This week, Delta reported a record quarterly profit of more than $1.8 billion and record revenue during the April-through-June period that includes the first part of summer travel season. United is scheduled to report results Wednesday, and analysts expect the airline to post a profit of more than $1.3 billion, according to a FactSet survey.

(AP)