Boeing CEO Dennis Muilenburg faced a litany of hostile questioning in a Senate hearing on Capitol Hill Tuesday, but mostly escaped being pinned down on key details related to specific failures that led to two fatal crashes of the 737 MAX.

His appearance at least clarified how the company accepts only limited accountability for what happened.

Muilenburg admitted that “we made mistakes, we got some things wrong.”

Yet, the only specific mistake he cited was that a warning light that should have indicated an error in an angle-of-attack sensor was not working due to a software glitch.

“We got the implementation wrong,” Muilenburg said of this error, which Boeing knew about more than a year before the first crash a year ago, but assessed as not serious.

A Boeing 737 Max 8 sits behind the Boeing 737 Renton factory waiting for engines. The Angle of attack (AOA) instrument of the 737 MAX, is the bottom piece of equipment below just below the cockpit windshield. 

Photographed on March 13, 2019 209611 209611

Regarding the much more significant flight-control software that was triggered by a single bad sensor and caused the planes to nose-dive — the Maneuvering Characteristics Augmentation System (MCAS) — Muilenburg stuck by Boeing’s insistence that the design and certification of that system was done according to “long-standing industry standards.”


Muilenburg said the accidents raise the question of whether the assumed pilot response times were not realistic. In other words, the focus is on whether assumed pilot competence has to be reassessed rather than Boeing’s.

Muilenburg flatly dismissed accounts that Boeing inadequately communicated the details of MCAS to the Federal Aviation Administration (FAA), despite investigative reports by safety agencies and regulators saying otherwise. And he never had to address how a design without redundancy passed muster during the MAX’s development.

Hostile comments

Muilenburg’s only discomfiting moments came when a few senators chose to vent.

Sen. Richard Blumenthal, D-Conn., abandoned questioning and went on a rant.

“My anger has only grown,” Blumenthal said as he accused Boeing of “a pattern of deliberate concealment.”

“Boeing came to my office shortly after the accidents and said they were the result of pilot errors,” he added. “Those pilots never had a chance.”


Calling the MAX aircraft “flying coffins,” he shouted that “you were lying to us” and accused Boeing of “putting profits over safety.”

Sen. Jon Tester, D-Mont., declared “I would walk before I would get on a 737 MAX … I see corners being cut.”

Tester then moved on and Muilenburg never did seize the opportunity to respond to this remark and offer reassurance to air travelers who might feel the same way.

One of the few senators to wait for Muilenburg to answer and then ask effective follow-ups was Sen. Ted Cruz, R-Texas, who read aloud the recently disclosed instant message exchange between two senior Boeing technical pilots in 2016, in which one of them talked about lying to the FAA.

Cruz drilled into why Muilenburg learned of this stunning exchange only when it became public, though the company had provided the document to the Department of Justice in February.

“How in the hell did nobody bring this to your attention?” Cruz asked.


Muilenburg for once was left fumbling. “I didn’t see the details,” he said. “I counted on my [legal] counsel to handle this appropriately.” And no, he had to admit, he had not talked directly to the pilot in the exchange who is still employed at Boeing.

But these were only passing moments of discomfort. Beyond that, Muilenburg, who continues testimony Wednesday, was able to keep his cool and get away with mostly vague answers lacking detail. He showed hints of emotion when the families of crash victims, seated just behind the Boeing executives, were asked to stand up and were invited to display photos of those who died.

As is typical of congressional hearings where politicians tend to grandstand rather than probe for real answers, the hearing proved a frustrating couple of hours for anyone seeking clear information on the crashes.

The senators for the most part made statements, rather than asking for answers. When they did ask questions, they often didn’t wait for Muilenburg’s answer. And when they did get an answer, they rarely asked pointed follow-up questions.

When Muilenburg was asked about multiple media reports, initially in The Seattle Times last March, that a significant change to MCAS late in the jet’s development — extending its authority to move the jet’s horizontal tail and push the nose down — was not fully vetted by the FAA, he flatly rejected this as “a false report.”

None of the senators followed up to ask how that squares with details in the final Lion Air investigation report.


That report noted that just the month after Boeing submitted to the FAA its revised system safety assessment — with MCAS authority extended — in November 2016, the FAA’s response was to simply “accept” the submission, with a note that approval was delegated to Boeing.

In any case, the report concluded, the FAA’s focus on the assessment “was mainly around other system changes and not MCAS.”

Talk to us

We continue to seek information on the design, training and certification of the Boeing 737 MAX. If you have insights, please get in touch with aerospace reporter Dominic Gates at 206-464-2963 or To communicate on a confidential and encrypted channel, follow the options available at

Similarly, a report earlier this month by an international panel of air-safety regulators found that Boeing submitted to the FAA an inadequate technical description of MCAS.

“The certification plans … were not updated to describe the expansion of the MCAS function,” the report said.

Boeing’s documentation of MCAS was fragmented and incomplete, the report added. “Although MCAS may have been briefed to some FAA personnel, key aspects … were not directly visible to the FAA in a straightforward manner.”

MCAS failure evaluation inadequate

Asked by Sen. Maria Cantwell, D-Wash., specifically about how Boeing evaluated MCAS during development, Muilenburg responded that “we do identify hazards and failure modes. That was part of the failure mode analysis that we shared [with the FAA] as part of the certification process.”


Again, this answer was allowed to pass without follow-up, though a National Transportation Safety Board (NTSB) paper that is part of the Lion Air accident investigation final report suggests Boeing’s evaluation of the MCAS failure modes was both inadequate and not well communicated to the FAA after MCAS’ authority was extended.

That report notes that Boeing conducted only a preliminary “Functional Hazard Analysis” (FHA) on MCAS  during early development of the jet in 2012, and that this evaluated the consequences of the system’s failure as a low-level event that would increase the crew’s workload but not threaten serious injuries.

“After the (MCAS) change, FHA was reviewed but not all documents including Stabilizer System Safety Assessment were updated,” the NTSB concluded. “Without documenting the updated analysis in the stabilizer SSA document, the FAA flight control systems specialists may not have been aware of the design change. Boeing did not submit the required documentation and the FAA did not sufficiently oversee Boeing.”

In addition to that inadequate communication of the FHA result, the categorization of an MCAS failure as low-level and relatively benign meant that Boeing did not follow up with two more detailed and rigorous analyses of MCAS later.

The Failure Modes and Effects Analysis and the Fault Tree Analysis, two standard evaluations of the consequences of failures that are conducted on all critical airplane systems, were not done for MCAS.

Too cozy with the FAA?

A separate line of questioning focused on the way Boeing itself conducts much of the certification work on a new jet for the FAA. Muilenburg defended this process of the government’s delegating oversight to the industry, citing the very low incidence of air accidents in the U.S. over the past decade.


“The data clearly shows that the creation of the delegated authority process … has enhanced safety,” he said. “The fundamental process of strong government oversight combined with deep industry technical knowledge is the right balance.”

Muilenburg rejected a suggestion that Boeing is “too cozy” with the FAA and dodged a push by Blumenthal to get him to commit to support legislation that would “reduce FAA outsourcing” of airplane certification work.

Instead the only systemic change Boeing talked about was reevaluating the industry assumptions on how quickly and well pilots will respond to an emergency.

John Hamilton, the vice president and chief engineer at Boeing Commercial Airplanes who assisted Muilenburg in answering questions, conceded that Boeing’s assumptions about how pilots would respond if MCAS misfired “did not happen” on the accident flights.

“That’s a fundamental issue we have to address in this industry,” Hamilton said.

Sen. Ron Johnson, R-Wis., asked Muilenburg why Boeing didn’t ground the MAX after the first crash in Indonesia.


“We have asked that question over and over,” Muilenburg replied. “If we knew everything then that we know now, we would have made a different decision.”

Ralph Nader, the longtime consumer advocate whose grandniece, 24-year-old Samya Rose Stumo, died in the Ethiopian crash of a 737 MAX, expressed skepticism before the hearing that the senators’ grilling of Muilenburg would achieve much.

“They’ll beat up on him, but it’s all Kabuki theater,” Nader said. “The questions are very tough. Then they unground the planes.”

Muilenburg said Boeing is in “the final stages” of completing its fixes for the MAX and that a certification flight with the FAA should happen “in the near term.”