PARIS (Reuters) – The head of Boeing Co said on Sunday the U.S. planemaker had made a mistake in implementing a 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 said 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 expected the MAX to return to service this year.

Boeing says it followed procedures when designing the 737 MAX. Asked how the procedures failed to capture apparent flaws in MCAS control software and sensor architecture, Muilenburg said: “Clearly, we can make improvements, and we understand that and we will make those improvements.”

He added: “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 was speaking on the eve of the Paris Airshow where the U.S. planemaker expects to make subdued order announcements for a number of larger wide-body jets.

He stuck to a previous timeline for the all-new 777X twin-aisle jet, which Boeing aims to fly later this year and deliver to airlines in 2020.

He said a possible new jet dubbed NMA had fallen behind the MAX’s return to service as a priority, but that the timeline on decisions and entry to service remained unchanged.

He took aim at European rival Airbus’s planned new extended-range A321XLR, saying the aircraft would only “scratch an edge” of the market segment targeted by the NMA, which would replace Boeing’s 757s and 767s.

Whether or not Boeing moves forward with the new mid-sized plane to serve a niche market falling between narrow- and wide-body aircraft is expected to reshape competition with Airbus, which dominates the top end of the medium-haul sector.