EVERETT, WA (MyBellinghamNow.com) – Boeing is waiting to learn whether 33,000 aircraft assembly workers are going to strike and shut down production of the company’s best-selling planes.

Members of the International Association of Machinists and Aerospace Workers are voting on whether to approve a contract offer that includes a 25% raise in pay over the course of four years.

If the factory workers reject the contract and two-thirds of them vote to strike, a work stoppage would begin on Sept. 13 at midnight.

Courtesy of AP Photo/Stephen Brashear

Union negotiators unanimously recommended that workers approve the tentative contract reached over the weekend. The union, among other demands, wants to restore traditional pensions that were axed a decade ago.

A walkout would not cause flight cancellations or directly affect airline passengers. However, it would be another blow to Boeing’s reputation and finances in a year marked by problems in its airplane, defense and space operations.

A strike would stop production of the 737 Max, the 777 jet and the 767 cargo plane at factories in Everett and Renton.

Voting began at 5 a.m. on Sept. 12 and results expected to be released the same evening.