About 33,000 IAM members have been on strike for seven weeks, shutting down production of most Boeing airline jets including the company's best-seller, the 737 Max.
The strike began Sept. 13 when more than 94% of workers voting rejected an offer of 25% over four years. Last week, 64% shot down a proposal that would have raised general wages 35% over four years.
The union originally demanded 40% in raises over three years and restoration of traditional pensions, which were frozen for then-current workers and not extended to those hired after January 2014. Workers on picked lines in the Seattle area have stressed pensions, but the company based in Arlington, Virginia, is unwilling to bend on the issue.