The Boeing chief executive, Dennis Muilenburg, will admit on Tuesday that the aircraft manufacturer made mistakes, and pledge that accidents like the two 737 Max crashes that killed 346 people will not happen again.
He will appear at a congressional hearing on the anniversary of the crash of Lion Air flight 610 in Indonesia that killed 189 people. In March, after an Ethiopian Airlines 737 Max crashed, killing 157 people, the plane was grounded worldwide.
According to written testimony, Muilenburg will tell the Senate commerce committee: “We have learned and are still learning from these accidents, Mr Chairman. We know we made mistakes and got some things wrong.”
Muilenburg’s testimony, made public on Monday, said the company had made improvements to the now-grounded 737 Max airplane “that will ensure that accidents like these never happen again”. He added: “We also know we can and must do better.”
Muilenburg, who was stripped of his title as Boeing chairman by the board earlier this month, will also testify before the House of Representatives transportation and infrastructure committee on Wednesday.
The grounding of the 737 Max has forced US airlines to cancel flights up to January and February and has also affected European carriers such as Ryanair, which cut 30,000 flights and will fly 5 million fewer passengers than planned next year. The Federal Aviation Administration (FAA) is not expected to approve the 737 Max’s use until December at the earliest.
Muilenberg will tell the Senate he has flown on two demonstration flights testing the improvements made to the 737 Max. “When the 737 Max returns to service, it will be one of the safest airplanes ever to fly,” he said in his written testimony.
He conceded getting the plane back in the air “has taken longer than we originally expected, but we’re committed to getting it right, and return-to-service timing is completely dependent on answering each and every question from the FAA”.
He added “regulators should approve the return of the Max to the skies only after they have applied the most rigorous scrutiny, and are completely satisfied as to the plane’s safety. The flying public deserves nothing less.”
Muilenberg also expressed “deepest sympathies to the families and loved ones” of those killed. He visited the Indonesian embassy in Washington on Monday to meet the country’s ambassador, offer condolences and pay respects to those lost on the flight.
Roger Wicker, the chairman of the Senate commerce committee, told Reuters last week the 737 Max “won’t fly unless 99.9% of the American public and American policymakers are convinced that it’s absolutely safe”.
Indonesian investigators reported last week that problems with Boeing’s design, the airline’s maintenance of the jet and pilot errors contributed to the Lion Air crash.
Muilenburg noted both crashes involved the repeated activation of a flight control software function known as MCAS after it received faulty sensor input.
Boeing’s development of that software has come under criticism from lawmakers and the company is adding safeguards to the system. Muilenburg said the changes would “eliminate the possibility of even extremely unlikely risks that are unrelated to the accident”.
Boeing has admitted few mistakes since the two fatal crashes. Earlier this month, the FAA questioned why Boeing withheld instant messages from a former pilot for months that raised questions about MCAS.
Representative Peter DeFazio, who chairs the House panel, has one main question for Boeing at Wednesday’s hearing: “How the hell did this happen?”