Victorville, CA / USA – March 27, 2017: The Boeing Company’s logo on wall of a building at the Southern California Logistics Airport in Victorville, California.

Boeing engineers and technical workers rejected the U.S. planemaker's four-year contract offer, union officials said on Friday.

The 17,000 members of the Society of Professional Engineering Employees in Aerospace also overwhelmingly voted to give the negotiating team the power to declare a strike when the contract expires in October, the union said.

SPEEA is Boeing's largest white-collar union.

Boeing did not immediately respond to a request for comment.

A union spokesperson said its negotiation team plans to survey members to see what it will take to approve a four-year contract with Boeing. The company offered better terms than expected, several union members said.

A work stoppage by SPEEA members would further delay Boeing's certification campaigns for its 737 Max 10 and 777-9 planes, both of which are several years behind schedule.

While the negotiating team endorsed the terms, neither of SPEEA's bargaining unit councils backed the offer.

The engineers and technicians units negotiate together with Boeing, but they vote separately.

Speaking to Wall Street analysts in July, Boeing CEO Kelly Ortberg said the company began discussions early, "to work towards an agreement that supports our employees and their families, creates greater clarity for our business and helps us stay focused on the progress we're making."

Boeing's offer included wage increases tied to inflation — capped at 3% — and individual performance, as well as other unspecified metrics determined by the company.

Several SPEEA members who voted to reject the offer told Reuters that capping inflation-based raises at 3% would nearly guarantee their salaries fall behind inflation.

The Consumer Price Index, an inflation benchmark, rose 4.5% over the past year for the Seattle area, where most SPEEA members work, the U.S. Bureau of Labor Statistics reported in July.

In 2024, Boeing commercial airplane production in the Seattle area ground to a halt when the roughly 33,000 members of the International Association of Machinists and Aerospace Workers went on strike for seven weeks.