Boeing Co. followed appropriate protocols in designing and certifying a system linked to two fatal 737 Max crashes, Chief Executive Officer Dennis Muilenburg said as he defended the airliner at the company’s annual meeting.

Muilenburg underscored the effort Boeing is putting into redesigning the software, a step needed to lift a global grounding of the single-aisle workhorse favored by budget carriers. But he wouldn’t agree that the original design of the best-selling jet was flawed, when grilled by reporters at a 15-minute briefing following the shareholder gathering in Chicago.

The system, which was activated by a single sensor reading in both crashes, remains a focus for crash investigators, Congressional and criminal probes centered on how the Max sailed through certification and into the commercial market in 2017. The gaps in Boeing’s narrative have irritated key airline customers while leaving family members of victims searching for the truth.

“Boeing has given no full account,” said Tarek Milleron, whose niece, Samya Stumo, died in the Ethiopian Airlines accident last month. He stood in the driving rain outside the Boeing gathering, holding up a photos to remind shareholders and executives of the victims. Stumo was also a relative of Ralph Nader, the consumer activist and former presidential candidate.

“They need to open up and reveal the chain of events inside their company that led to these crashes,” Milleron said. “That’s where the truth resides, in the relationship between Boeing and the FAA and in Boeing’s own process. They had a very powerful sales and marketing drive and they misrepresented their product.”

Muilenburg opened the annual meeting with a moment of silence for the victims and repeatedly vowed to reinforce the planemaker’s integrity and safety in the wake of the accidents, which have plunged Boeing into a public relations and financial crisis.

Boeing was little changed at US$380.51 at 1:04 p.m. in New York.