Boeing machinists voted, by a large majority, to return to work after a 57-day strike ground the aeronautics giant's operations to a halt, their union said.

After federally mediated talks, union members voted to back the deal with a 74-percent majority, the International Association of Machinists and Aerospace Workers (IAMAW) union said.

"Our Union has delivered what few Americans have - economic certainty and quality benefits for the next four years," the IAM statement said.

"It also recognises the need to act with foresight to protect the next generation of aerospace jobs," it said.

The union said medical benefits would remain unchanged through 2012.

The strike was estimated by some analysts to be costing the company more than US$100 million per day and risked further delaying the launch of Boeing's new passenger jet, the 787 Dreamliner.

Boeing's 27,000 machinists, who represent 16 percent of the company's workforce, began picketing on September 6 after last-ditch contract talks broke down.

The two sides resumed federally mediated talks last week to break the deadlock.

Hurt by the strike, 787 delays and a difficult economic environment, Boeing last week announced a 38 percent fall in third-quarter net profit.