Boeing's (NYSE:BA) 777X, already delayed until 2022, might not arrive until 2023 or even later, according to the plane's most important customer.

In an interview today with Reuters, Tim Clark, president of Emirates, said his airline is not assuming the plane will arrive in 2022 as anticipated. Emirates represents about one-third of the 777X order book, but the airline has said previously it could consider swapping some of its orders with different planes depending on market conditions and how long it will take for the 777X to arrive.

The 777X is an update on Boeing's long-haul workhorse, and will be the first new plane the company attempts to get certified since the 737 MAX. The MAX rollout did not go to plan, with the plane grounded for 20 months after a pair of fatal accidents, and Clark is expecting heavy regulatory scrutiny to be applied this time around.

He told Reuters the 777X certification could happen in 2022, or "could be '23, it could be even longer," saying Emirates "will just wait and see as to what Boeing will do with regard to that, and we will take a view as to how they fit into the fleet at that particular time."

Boeing had originally hoped to have the 777X ready by now, but a combination of tepid demand and failed tests pushed back the timetable. The plane flew for the first time last year, but even prior to the pandemic, Boeing seemed unlikely to start deliveries until at least 2021.

The 737 MAX, which makes up the bulk of Boeing's order book, has been cleared to resume service. The company is likely to lean heavily on 737 sales and deliveries in the years to come as airlines plot slow recoveries and de-emphasize larger jets like the 777 and the 787 Dreamliner.

A Boeing 777X airplane A Boeing 777X airplane taxis for the first flight, which had to be rescheduled due to weather, but the company will try again Saturday Photo: AFP / Jason Redmond

This article originally appeared in the Motley Fool.

Lou Whiteman has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.