A certification flight for Boeing's 737 MAX aircraft is not yet scheduled as there are still a few "issues to resolve", a top US air safety regulator said Tuesday.
The model has been grounded since March 2019 following two crashes that claimed 346 lives.
Federal Aviation Administration chief Steve Dickson said last week that a MAX certification flight could take place in a few weeks, a key step before the aircraft can return to service.
Giving an update to reporters in Singapore Tuesday, Dickson said that "we are approaching a milestone, the certification flight is the next major milestone.
"Once that is completed, I think we'll have a good bit more clarity on whether the process goes forward."
But he added the flight was not scheduled yet "because we still have a few issues to resolve... We are waiting for proposals from Boeing on a few items".
He refused to be drawn on when the grounding of the plane might finally be lifted, saying that regulators were following a "very diligent process".
"It's important that we stay focused on the process, and not on the timeline," he said on the sidelines of the Singapore Airshow, the biggest aerospace event in Asia.
After repeatedly missing its goals for resuming flights last year, Boeing is targeting a mid-2020 return, but says the timeframe will depend on regulators.
Boeing last month reported its first annual loss in more than two decades as the lengthy grounding of the 737 MAX undercut the company's revenues and exploded costs.
© 2020 AFP