Boeing said its 777X aircraft's first test flight would take place on Friday after bad weather delayed its scheduled takeoff on Thursday.
Boeing has previously said the 777X, its largest-ever twin-engined model, designed to hold on average 406 people, was on track to be delivered in 2021. It was originally due to be delivered in mid-2020.
Boeing said on Thursday weather or other factors could still delay the test flight.
The delay in the first flight of the large wide-body jet comes amid the grounding of the company's 737 MAX. The crisis surrounding the smaller jet following two fatal crashes has led new Chief Executive Officer Dave Calhoun to send the aerospace giant back to the drawing board on proposals for a new mid-market aircraft.