"The engagement on 777X continues. I believe it will be launched and we'll see that in six to nine months," Tim Clark told reporters in Dubai.

Emirates has been pressing Boeing for the aircraft, provisionally called the 777X, to come out sooner rather than later.

The 777 is one of the most successful jets of all time in terms of sales, and airlines are eager for a version that can go farther on less fuel with more passengers.