The head of Boeing says the US plane maker made a mistake in implementing a faulty cockpit warning system on the 737 MAX and predicted it would take time to rebuild the confidence of customers in the wake of two fatal crashes.
Chairman and chief executive Dennis Muilenburg says Boeing failed to communicate "crisply" with regulators and customers, but defended the broad engineering and design approach to nose-down control software at the centre of probes into the accidents that led to the plane's worldwide grounding.
Muilenburg acknowledged the company made a mistake in failing to disclose a defective cockpit warning light on its 737 MAX to regulators and customers, and said that failure has been part of reviews by global regulators.
Muilenburg, who has been under fire over the MAX design and Boeing's handling of the crisis, said "we are seeing over time more and more convergence among the regulators" on when the MAX should return to service.
He said he expected the MAX to return to service this year, and that 90 per cent of customers had participated in simulator sessions with its upgraded MCAS software, as the company works towards a certification flight with regulators soon.
Boeing says it followed long-standing engineering procedures when designing the 737 MAX.
Muilenburg was asked how the procedures failed to capture apparent flaws in MCAS control software and sensor architecture.
"Clearly, we can make improvements, and we understand that and we will make those improvements," he replied.
"When I make comments about the previous MCAS design and how we followed those processes, that's something we put a lot of thought and depth of analysis into. That doesn't mean that it can't be improved."
Muilenburg's comments on Sunday, on the eve of the Paris Airshow, highlight efforts by Boeing to strike a different tone than it did in the days after the Lion Air crash in October, when it raised questions over pilot and maintenance issues.
Muilenburg said the US plane maker expected to announce some orders at the show for wider-body jets, but that its main focus at this year's industry gathering was safety.
Australian Associated Press