The strike has paralysed operations at Boeing since early September
US planemaker Boeing has reached a tentative deal to end a strike by assembly workers, say union and management representatives.
The four-year settlement would improve job security and limit outsourcing.
Some 27,000 Boeing workers walked off the job on 6 September in protest over pay, outsourcing and other issues.
Analysts says the strike has been costing the airline manufacturer $100m a day, as delivery of finished planes dropped by more than 40%.
The two parties reached the agreement late on Monday, at the end of five days of talks in Washington DC.
The International Association of Machinists and Aerospace Workers (IAM) would not confirm full details of the agreement, but president Tom Buffenbarger said it "addressed all the major concerns" of union members.
The agreement is believed to address the major issues of outsourcing, including access to the shop floor for subcontractors and procedures for the union to bid for work before it is outsourced.
IAM said the deal had their unanimous endorsement and would be put to a vote in three to five days.
"The members make that final decision, but I'm hopeful," said Mr Buffenbarger.
Boeing has had a difficult six months. The global economic crisis, fluctuating oil prices and concerns about the financial viability of several airlines have all led to its share price plummeting 41% over the period.
However, the company has said that it can cope, even if strike action were to last longer.
The president of Boeing Commercial Airlines, Scott E Carson, said the proposed deal would reward employees for their contributions to the company's success, while also preserving Boeing's competitive ability.
Meanwhile, the brokers of the talks praised both parties for their commitment to the mediation process.
"Both sides showed professionalism and a willingness to roll up their sleeves and to stick with the difficult task in front of them," said the director of the US Federal Mediation and Conciliation Service, Arthur Rosenfeld.