Boeing says that strong demand for the 777 Freighter is aiding the production transition from the current 777 to the new 777X as it works to mitigate the impact of the latter’s delay.

The key difference between the current production 777s and the new 777X, which comprises the 777-8 and -9 variants, is the wing structure, which is switching from “metal” to carbonfibre.

Deliveries of 777-9s were due to begin by mid-2020 as the -300ER was phased out. However, the delay to the start of 777-9 flight-testing – which should have begun by mid-2019 – means that deliveries are unlikely to start before 2021, despite Boeing’s stated intention to keep it within 2020.

Boeing secured two additional 777-300ER orders last month from KLM and currently has 34 left on firm backlog to deliver, plus two 777-200LRs. However, Boeing sold 45 777Fs in 2018 with a further 15 added so far this year, and is using the -200LR-based variant to aid the production bridge.

“With the strong demand for the 777F, we have inserted additional positions into the ‘skyline’ in lieu of 777X positions,” Boeing tells FlightGlobal.

Boeing chief executive Dennis Muilenburg acknowledged during the second-quarter earnings briefing in July that, although it is “still holding 2020” for first the 777X delivery, “we know there’s clear pressure on that given the delays in first flight. So we are taking a look at production skyline mix in 2020… and we anticipate that means we’ll probably build more current-generation 777s, 777 Freighters in that timeframe.”

Muilenburg shed more light on bridge planning during the Morgan Stanley conference in September, saying: “We continue to see opportunities [for 777F sales], and where we can capture those, we’ll feather those into the skyline. That does mitigate risk for us and gives us some more schedule flexibility, if you will, on the overall production line.”