Boeing (BOE, Chicago O'Hare) has deferred the first flight of the B777-9 to early 2020 due to the delay in certification of the General Electric GE9X engine. The American manufacturer said in its quarterly results that the programme was "progressing well through pre-flight testing". "While the company is still targeting late 2020 for first delivery of the 777X, there is significant risk to this schedule given engine challenges, which are delaying first flight until early 2020," Boeing said. Speaking during the investor call, CEO Dennis Muilenburg said that Boeing was planning to build more B777-Fs in 2020 instead. "We've made progress on continuing to sell 777 freighters including during this last quarter. We continue to see strong demand signals there. And so [we have] ability to maintain the production system at five a month and alter the delivery mix between 777s and 777X," Muilenburg said. Boeing initially planned the first flight of the B777-9 in 2019. The first two aircraft of the type, are already in pre-flight ground testing at Everett. The first flight is delayed by issues with the GEX9 engine high-pressure compressor.