We know we made mistakes on 737 MAX: Boeing CEO Dennis Muilenburg

Muilenburg, who was removed as Boeing chairman by the board earlier this month, will testify before the US House of Representatives Transportation and Infrastructure Committee on Wednesday

Boeing Co Chief Executive Dennis Muilenburg will acknowledge on Tuesday before Congress that the aircraft manufacturer made mistakes after two deadly 737 MAX crashes killed 346 people, according to written testimony seen by Reuters.

"We have learned and are still learning from these accidents, Mr. Chairman. We know we made mistakes and got some things wrong," Muilenburg will tell the US Senate Commerce Committee.

The testimony, which Boeing has not made public, adds that the company has made improvements to the now-grounded airplane "that will ensure that accidents like these never happen again."

Muilenburg, who was stripped of his title as Boeing chairman by the board earlier this month, will then testify before the US House of Representatives Transportation and Infrastructure Committee on Wednesday.

US airlines have canceled flights into January and February because of the grounding and the Federal Aviation Administration (FAA) is not expected to approve its ungrounding until December at the earliest.

"We also know we can and must do better," Muilenburg's testimony says. He also expresses "deepest sympathies to the families and loved ones" of those killed, noting the hearing is taking place on the anniversary of Lion Air Flight 610.

Indonesian investigators reported on Friday that Boeing, acting without adequate oversight from US regulators, failed to grasp risks in the design of cockpit software on its 737 MAX airliner, sowing the seeds for Lion Air 610 that also involved errors by airline workers and crew.

Muilenburg noted that both crashes involved the repeated activation of a flight control software function known as MCAS after it got faulty sensor input. Boeing's development of that software has come under criticism in reports and from lawmakers and the company is added significant safeguards to the system. He said the changes would "eliminate the possibility of even extremely unlikely risks that are unrelated to the accident."

He acknowledged that getting the plane 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 that "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."