A Boeing 737 Max jet, piloted by Federal Aviation Administration (FAA) chief Steve Dickson, prepares to land at Boeing Field following a test flight in 2020 in Seattle. Elaine Thompson/Associated Press, file

Boeing’s largest employee union voted overwhelmingly Wednesday to authorize a strike, increasing the pressure on the company to meet its demands for higher wages and better working conditions or risk a crippling walkout later this year.

Wednesday’s yes vote by members of the International Association of Machinists and Aerospace Workers District 751 was largely expected but injects yet another element of uncertainty into Boeing’s business as it attempts to recover from a string of crises that have weighed on its reputation all year. Union officials said the vote passed by nearly 99.9%.

“We don’t want to strike – but we’re ready and willing to do so to bring home the best aerospace contract our members have ever seen,” Jon Holden, president of IAM District 751, said in a statement after the vote. “There is no Boeing without us, and we have what it takes to build this company back to the level it was.”

Negotiations between Boeing and the 32,000-member union began in March to replace the current agreement, which expires Sept. 12. A strike in September would require another membership vote.

Boeing has been grappling with multiple investigations and controversies over safety and manufacturing integrity all year. In January, a 737 Max operated by Alaska Airlines suffered a midair door panel blowout, leaving a gaping hole in the fuselage as the plane was forced to land. This month, Boeing agreed to plead guilty to a charge of conspiracy to defraud the government over crashes of 737 Max jets in Indonesia in 2018 and Ethiopia in 2019 that killed 346 people. The agreement with the Justice Department followed a finding by prosecutors that Boeing failed to live up to the terms of a deal the company negotiated with the government in 2021 that would have shielded it from criminal prosecution.

Now its labor issues loom large. The union’s proposal includes a pay increase of more than 40% and restoration of the traditional pension program that was eliminated in 2014. While pay and benefits are important, after several years in which Boeing threatened to move aircraft production elsewhere, Holden, IAM District’s 751’s president, said one of the union’s top priorities is ensuring that the company’s next new airplane is built in Washington state.

Boeing has not announced plans for a new plane and declined to comment on where such a plane would be built. However, its threats to move production to another state in 2008, 2011 and 2014 enabled it to win concessions from union members eager to keep production in Washington.