Some 59% of union members voted in favour of the accord, which includes a 38% wage increase over four years and enhanced retirement contributions, according to the International Association of Machinists and Aerospace Workers district representing some 33,000 striking workers.
“This was a defining moment tonight,” IAM District 751 president Jon Holden said.
“This is a victory. We stood strong, we stood tall, we won,” he said more than 26,000 votes had been cast, adding that “I just want to get our members back in the factory”.
Hourly workers can start returning to factories in Washington, Oregon and California as soon as Wednesday.
The breakthrough represents a major victory for new Boeing CEO Kelly Ortberg, clearing the way to move forward with plans to rebuild the company’s culture and improve the quality of work in its factories.
Three previous overtures failed to win workers’ endorsement, heaping pain on a company already reeling from a near-catastrophic accident in January that upended its production, finances and senior management.
Union negotiators had endorsed the proposal, warning that another rejection risked losing gains secured through weeks of collective bargaining.
The favourable vote provides a much-needed respite to Boeing, which said last month that it will likely continue to burn cash in 2025 as it grapples with the challenges of eventually ramping up airplane production when the strike ends.
Monday’s late-night vote came after the company raised more than US$23 billion last week to shore up its balance sheet and fund its recovery.
The strike added to the financial strain on Boeing, costing it about US$100 million in lost revenue a day by some estimates.
While Boeing averted a likely downgrade of its credit rating to junk status by raising more than US$24 billion in capital, it’s not out of the woods yet.
The company now faces a long slog as it restarts its factories and nurses suppliers back to health.
As well as raising pay by 38%, the planemaker’s fourth proposal for a four-year contract gives hourly workers a US$12,000 signing bonus upon ratification and boosts contributions to retirement savings plans.
It won’t restore pensions, a key point of contention for some veteran employees.
Jefferies analyst Sheila Kahyaoglu estimates Boeing faces about US$1.1 billion in higher salary costs over four years under the deal.
Ortberg instituted a range of cost cuts to weather the fallout from the strike, including a 10% reduction in the workforce alongside hiring freezes and travel restrictions to conserve cash.
Ortberg took over in August following a shakeup of senior management in the wake of cascading crises that have rocked Boeing since the start of the year.