Boeing’s new chief executive Kelly Ortberg has pleaded with workers to not go on strike as it would put the company’s “recovery in jeopardy”.
It comes hours ahead of a crucial union vote that could trigger industrial action at the embattled company.
The aviation giant’s executives and union representatives reached a deal earlier this week that includes a 25% pay rise over four years but it has yet to be approved by union members.
If workers vote against the agreement it would lead to a second ballot on whether to start a strike as early as Friday.
“I ask you not to sacrifice the opportunity to secure our future together, because of the frustrations of the past,” said Mr Ortberg in his message to staff.
“Working together, I know that we can get back on track, but a strike would put our shared recovery in jeopardy”.
The current contract between Boeing and the unions was reached in 2008 after an eight-week strike.
In 2014, the two sides agreed to extend the deal, which is due to expire at midnight on Thursday.
It comes as the company faces deepening financial losses and continues to struggle to repair its reputation following recent incidents and two fatal accidents five years ago.