FILE PHOTO: Several Boeing 777X aircraft are seen in various stages of production during a media tour of the Boeing 777X at the Boeing production facility in Everett, Washington, U.S., February 27, 2019. REUTERS/Lindsey Wasson

DUBLIN (Reuters) - Boeing BA.N plans to carry out the first test flight of its delayed 777X airplane later this week, said two people familiar with the matter on Tuesday.

A source close to one of the wide-body jet’s nine firm customers said the flight would take place on Thursday or Friday at Boeing’s commercial base outside Seattle, depending on weather.

Another person familiar with the program said the flight would happen late this week.

Boeing could not immediately be reached for comment.

Boeing has said its largest ever twin-engined model, designed to hold on average 406 people, would fly for the first time in early 2020, with the first jet on track to be delivered in 2021. It was originally due to be delivered in mid-2020.