CNN: Boeing acknowledges flight control system’s role in crashes, promises ‘disciplined approach’ to fix

Posted on April 04, 2019

(CNN) Boeing said for the first time Thursday that an anti-stall system on its 737 Max model had played a role in two recent plane crashes, an acknowledgment that will heighten the scrutiny the company is facing as it works to return its signature aircraft — currently grounded by aviation regulators around the globe — to the skies.

Dennis Muilenburg, the company’s CEO, made the acknowledgment in a statement following the release of a preliminary report by Ethiopian investigators that found that a malfunctioning sensor on an Ethiopian Airlines flight last month was sending incorrect data to the plane’s flight control system.

According to the report, the pilots battled the system as it pushed the nose of the aircraft down, responding to faulty data from the angle of attack sensor that appeared to show the plane directed too far up and at risk of stalling.

The problems on board the Ethiopian Airlines jet mirror those encountered on the Lion Air flight that crashed in October. Between the two crashes, 346 people were killed.

Boeing announced last week that it had developed a fix to the anti-stall system, known as the Maneuvering Characteristics Augmentation System, that it was ready to submit for final regulatory approval, though on Monday it delayed that submission, later citing the discovery of an additional “relatively minor” issue.

“It’s apparent that in both flights the Maneuvering Characteristics Augmentation System, known as MCAS, activated in response to erroneous angle of attack information,” Muilenburg said Thursday, calling the system one link in a “chain of events” that caused the crash.

“It’s our responsibility to eliminate this risk. We own it and we know how to do it,” Muilenburg said.

The Federal Aviation Administration certification process for the MCAS software update has taken place in a separate procedure than the initial review of the Boeing 737 Max, which has been criticized for its reliance on designated Boeing employees for certain sign-offs.

While Boeing and the FAA have been working in lockstep since the company began its redesign of the software after the Lion Air crash last year, final certification for the update will fall to FAA officials, not Boeing designees, a person familiar with the process said.

That is standard procedure for a specific update or fix to an individual part, versus the years-long certification of a new airplane model, which allows for the approval of certain elements of design and airworthiness by specifically designated Boeing employees, in accordance with a long-standing agreement between the manufacturer and the FAA.

Boeing first submitted a proposed certification plan to the FAA in January for the update, and the FAA has since participated in simulator tests to the new software. On March 12, the FAA went up on a Boeing certification flight to test the new software, a Boeing official said.


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The updated software will include data from a second angle of attack sensor and will no longer be able to produce an angle that cannot be counteracted manually by a pilot.

“This update, along with the associated training and additional educational materials that pilots want in the wake of these accidents, will eliminate the possibility of unintended MCAS activation and prevent an MCAS-related accident from ever happening again,” Muilenburg said in the statement Thursday.

The update design had appeared to be going smoothly and approaching conclusion last week. A Boeing official had said then that the company was planning to send the update to the FAA for final certification by last Friday, and that Wednesday, Boeing unveiled the new software to a gathering of aviation officials at its Renton, Washington, facility.

Later in the week, however, Boeing employees going through a final check, called the non-advocate review process, identified integration issues with the new software, a Boeing official said. That review process, a regular layer of oversight at the company, involves inspection of a program by Boeing employees that did not work on its development.

A Boeing spokesman later said the problem in the updated software that was discovered in the non-advocate review process was unrelated to MCAS and “relatively minor.”

On Monday, Boeing notified airlines that flew the Max and aviation regulators that there would be a delay in submitting the final certification for the update, two people familiar with the timeline said.

Boeing has said the completed update will be sent to the FAA for final review in “the coming weeks.”

“We’re taking a comprehensive, disciplined approach, and taking the time, to get the software update right,” Muilenburg said Thursday, adding an apology for the deaths due to the crashes and a recognition that “all of us feel the immense gravity of these events across our company.”

Lawmakers have slammed Boeing and the FAA for the regulatory agreement that takes workload off of government inspectors and puts it on the manufacturer.

“The fact is that the FAA decided to do safety on the cheap, which is neither safe or cheap, and put the fox in charge of the henhouse,” Sen. Richard Blumenthal, a Connecticut Democrat, said at a hearing last week.

Michael Goldfarb, a former FAA chief of staff, said the fixes to the 737 Max will likely take months, not weeks, because Boeing does not want to “create a bigger problem than was fixed.”

“This will be treated differently from the way business is done,” Goldfarb told CNN of the FAA review of the update. “This will be micromanaged from Secretary Chao down.”

Transportation Secretary Elaine Chao told a Senate panel last week that she was “concerned” about the allegations of coziness between FAA and Boeing but she defended the practice of company employees handling certification responsibilities.

“I am of course concerned about any allegations of coziness with any company, manufacturer,” Chao said. “These questions, when they arise, if they arise, are troubling because we should have absolute confidence in the regulators that they are certifying properly.”

Muilenburg was aboard a test flight of the 737 Max in Seattle on Wednesday for a demonstration of the updated MCAS software, according to Boeing spokesman Gordon Johndroe.

The software worked as designed and the plane landed safely, Johndroe said.

CNN’s Gregory Wallace contributed to this report.