Boeing and its largest union said Sunday they reached agreement on a new contract that, if ratified, will avoid a strike that threatened to shut down aircraft production by the end of the coming week.

Boeing said 33,000 workers represented by the International Association of Machinists and Aerospace Workers would get pay raises of 25% over the four-year contract, with average wages rising 33% due to seniority step increases. That is less than the 40% the union had demanded during negotiations.

But the company agreed with a key union demand to build its next plane in Washington state, presumably by union members.

Workers also would get $3,000 lump sum payments and a lower share of health care costs, Boeing said. The company would make new 401(k) contributions of up to $4,160 per employee, but the union would not achieve its demand to restore a defined-benefit pension plan that was eliminated in 2014.

“Negotiations are a give and take, and although there was no way to achieve success on every single item, we can honestly say that this proposal is the best contract we’ve negotiated in our history,” Jon Holden, president of IAM District 751, the machinists’ union outpost at Boeing, said in a statement posted on the union website.

The union’s bargaining committee is recommending that members ratify the contract, Holden said.

The president of Boeing’s commercial airplanes division, Stephanie Pope, said Sunday in a video for employees that the proposed contract includes the company’s largest-ever general wage increase. She said the promise to build Boeing’s next new airliner in the Puget Sound area means job security for generations to come.