A week after the Lion Air crash last October, Boeing issued a service bulletin to all airlines operating the MAX that identified a new flight control system on the airplane, known as MCAS, that had erroneously activated on the Lion Air Flight due to a faulty sensor. My stories quickly focused on the potential design flaws in this system. By January, I was following leads that indicated the certification of this system had been deeply troubled. In early March, I asked Boeing for comment on the details of a story that laid out how Boeing had done the certification work on the MCAS system and identified serious flaws in its safety analysis. Four days later, the second plane crashed in Ethiopia.

Soon it was clear that the trajectory of that flight was similar to the Lion Air flight, with MCAS again erroneously triggered by the same faulty sensor. Within days the MAX was grounded around the world, with the FAA the last major regulator to fall in line. My Seattle Times colleagues and I followed up with stories on the victims of the Ethiopian crash, on the baffling decision to design the system so that it was activated by a single Angle of Attack sensor, on why the emergency instructions Boeing issued after the Lion Air crash failed to save the Ethiopian airliner, and about how the current FAA safety chief, working to placate industry, pushed more delegation of oversight to Boeing.

We continue to work on follow-up pieces, with all the stories collected here on our 737 MAX page.

Proof: https://i.redd.it/1u4ohs1gz3u21.jpg


Edit: Time's up. I have to get back to work. Thanks everyone for the questions.

Comments: 663 • Responses: 25  • Date: 

SneekyDetective285 karma

Hi Dominic. I've been reading your work and it has been outstanding! Hear is a question that puzzles me:

For the entire MAX family, why didn't/couldn't Boeing utilize the newly designed telescoping main landing gear of the 737 MAX 10, which extends 9.5" longer than the same gear on the MAX 8/9?

Perhaps this additional ground clearance would have allowed the Leap engines to be located back underneath the wings where the NG's engines were, thus mitigating the pitch up effect to a large degree?

seattletimesnewsroom322 karma

I don't know the answer.

BrewCityChaser225 karma

What are some of common myths that are surrounding this story right now?

seattletimesnewsroom834 karma

I wouldn't say it's a myth, but one narrative that has gained ground on social media is that because Boeing added this software flight control that the MAX must be an inherently unstable airframe and that Boeing merely slapped a software "band-aid" on it. In other words, this plane is doomed to fail.

I don't believe this is true. Using software to adjust the flight characteristics of a modern jet is not unusual. When Boeing flight tested the latest version of its 747 jumbo jet, the 747-8, it found wing flutter (excessive vibration caused by resonance) in certain flight conditions. A Boeing engineer called Pio Fitzgerald won Engineer of the Year when he came up with a fix. The fix was software that detected the slightest onset of flutter on the wings and made the flaps and ailerons move slightly to counter it. Problem solved. No hardware. Just software. There's nothing unstable about the 747.

purgance99 karma

This is an interesting observation, because it seems to imply that the underlying issue is either the implementation of the fix, a problem intrinsic to the AoA sensor(s) (ie, a hardware problem), or a combination of the two.

Is there any indication as of yet which if any of these is true?

seattletimesnewsroom186 karma

I think it's clear the design of the MCAS software was poor. Boeing is now working on a software update to fix it.

And it's also clear that there is something wrong with two AOA failures, indeed three, months apart. (The lion Air jet had an AOA failure two flights before the fatal crash flight and that that sensor was replaced.)

There's a long way to go before we know everything that went wrong in the chain of events that led to each crash. But these two things we do know need attention.

FalconJetCaptain208 karma

Is there any documented cases of the same AOA failure happening to other aircraft other than these two?

seattletimesnewsroom302 karma

AOA failures happen on other aircraft. It's not common, but it happens. It's not generally fatal. What we have here is a critical flight control system dependent on one specific AOA sensor.

FalconJetCaptain81 karma

It would be interesting to know how many times this has happened to other crews which ended successfully (other than the LionAir flight the day before the crash).

seattletimesnewsroom47 karma

It has not happened on any other MAX flights.

cherokeesix113 karma

The New York Times published a damning article about 787 production in Charleston. Are you aware of similar issues in Renton or Everett?

seattletimesnewsroom162 karma

I've written about concerns over changes Boeing is making to its Quality Assurance system, including reducing the number of quality inspectors. This has caused concern not only about jobs but about the quality of the oversight.

See these two stories:



efisk66661 karma

In terms of executive responsibility, the second accident is much more troubling than the first. The first accident was the result of a serious engineering design mistake, but that can dealt with by apologizing and compensating victims and changing processes and designs going forward.

The second accident was caused by somebody high up the chain at Boeing choosing to ignore safety issues and keep the plane flying, and the workaround they published apparently didn't even actually work in real world conditions (manual override wasn't physically possible at flight speeds). So, questions...

Was the workaround to the MCAS issue ever tested in a real flight, and if so why didn't they see the problems that happened at Ethiopian airlines?

Second, which executive at Boeing is responsible for keeping the plane flying after the first accident, and can they be held criminally responsible?

seattletimesnewsroom108 karma

I believe it's true that Boeing bears some heavy responsibility for the second accident, but not in the way you frame it.

Boeing believed that by telling every MAX pilot in the world about MCAS and about how to handle any recurrence of what happened to the Lion Air pilots, using the Stabilizer Runaway checklist, that the plane would then be perfectly safe. In that case, there was no need to ground the fleet.

Where Boeing seems to have erred badly is in not providing more detail about that checklist. The instructions failed to warn pilots of the potential scenario that the Ethiopian pilots faced. They jumped too early to cut out electrical power to the tail, but then found the manual wheel jammed. Boeing needed to provide much more detail than they did about this procedure. It needed more explicit warnings about what could go wrong. If Boeing had done so, the MAXs could have kept flying safely.

dash_trash31 karma

but then found the manual wheel jammed.

Isn't this a little misleading? It wasn't "jammed" in the sense that there was something blocking the mechanism, it was simply impossible for the crew to operate using only unaided physical strength due to the higher than normal control forces on the stab. If the stab is only trimmable using the same electrical channel that the MCAS uses, doesn't that negate any redundancy in that critical system and therefore present in inherent design flaw? In other words, in what way could these pilots have possibly overcome this situation if they required the very system (electric trim) the checklist called for to be disabled to regain control?

edit: apologies, just read your comment here that clarifies things a bit

seattletimesnewsroom67 karma

The checklist instructs pilots to pull the nose back up using the electrical thumb switches before using the cut-out switches. They didn't appear to do that, perhaps understandably. Ultra-aware of what had happened to Lion Air JT610, they jumped to the cut-out switches first. The instructions from Boeing did not emphasize for pilots that this could jam the tail and make the manual trim impossible.

efisk66619 karma

Wouldn't those issues have been uncovered with real world testing? The second accident profile was nearly identical to the first, so if Boeing had put a pilot in a Boeing max plane and simulated the mcas failure they would have seen their workaround instructions were insufficient.

Do you know what real world flight testing went into approving the workaround?

seattletimesnewsroom44 karma

We don't know. Good question.

My guess is none. Boeing had motivation to point to this standard procedure, known by all pilots for years, and to say there's what you do, no need for further instruction. Implicit in that position is that the Lion Air pilots should have known this. In that pointing at the pilots, it was not in Boeing's interests to suggest that any more work was needed. Just follow the standard checklist.

But it turned out not so easy to do for the Ethiopian pilots.

thatguy31415952 karma

The media has mentioned that Boeing was tasked with some elements of what is being called "self certification" with some elements of the 737 Max 8 certification process. During the testing Boeing would have been doing for this, would there be individuals with the FAA on the team performing the tests/doing oversight? Or would the "self certification" team be made entirely of company personnel?

seattletimesnewsroom125 karma

There would have been FAA pilots on some of the MAX flight tests.

However, for the safety and compliance analyses, these were done almost entirely by Boeing engineers, the real subject matter experts. Their evaluations were sent to the FAA when finished for sign off.

However, as my March 17 story related, many of the FAA safety engineers felt under constant pressure and often felt they were not given enough time to do proper assessments of the Boeing documents.

seattletimesnewsroom62 karma

That March 17 story is here, if you want to read it: Flawed analysis, failed oversight: How Boeing, FAA certified the suspect 737 MAX flight control system

-- Nick Eaton, Seattle Times digital audience editor

TooMuchDamnSalt31 karma

Hi Dominic, to what extent do you feel this is s regulatory issue (i.e. the regulatory system enabled the flaws in training, certification, software testing etc)? Are there other changes to Boeing planes that have been though similar "lite-touch" regulation that should be revisited in light of this?

seattletimesnewsroom82 karma

I believe these crashes highlight serious regulatory shortcomings. In the past ten years, two new Boeing airplanes have entered service, the 787 Dreamliner and the 737 MAX. Both were grounded for safety issues.

The Dreamliner was grounded for 3.5 months in 2013 after inflight incidents of smoking,overheated batteries. No one died. Still, this was very serious. How were those batteries certified and approved safe?

Now we have the MAX grounded. And the big question is: How was this MCAS system certified and approved safe?

Something is wrong when two new airplanes have to be grounded.

And Boeing's next new airplane, the 777X, is lined up in Everett almost ready for its first flight.

arf141028 karma

I've heard conflicting information as to whether or not the Ethiopian flight crew actually followed the correct procedures to regain control of the airplane?

seattletimesnewsroom96 karma

It looks to me from the flight track data that the Ethiopian crew realized MCAS was causing the nose-down movement and because of the Lion Air crash knew that they must now use the Runaway Stabilizer checklist. Unfortunately, it looks like they jumped the gun and skipped a step, going immediately to hit the cut-out switches that stopped the uncommanded and indeed all electrical power to the tail.

That stopped MCAS, but they were now required to move the tail manually using the stab trim wheel. That proved impossible to budge because the stabilizer was in the max nose-down position and they were pulling on the yoke putting the elevator in max nose-up position and these forces jammed against each other, locking the system. They should have used the thumb switches to move the stabilizer and ease those forces before the cut-out. However, I don't blame the pilots for this sequence. The instructions Boeing had provided following the first crash did not tell them that it was critical to ease the stabilizer back up before hitting the cut-off.

The above is based on what the flight data looks like. There is much more going on in the cockpit, not all of which we know the details of. But I think the above account is why, despite trying to follow Boeing's checklist, they still failed to save teh jet.

KU7CAD20 karma

Will this drive real change to the FAA and the BCO?

seattletimesnewsroom22 karma

I hope so.

GGAllinsMicroPenis12 karma

Are any of these planes still flying right now, or are they all grounded without exception?

seattletimesnewsroom47 karma

They can be flown without passengers to be positioned for storage.

And Boeing has flown 135+ test flights of MAXs with the new software update installed.

bjor_ambra6 karma

Hi Dominic. What's your background? Are you a pilot or a journalist that's passionate about / assigned to this beat?

seattletimesnewsroom15 karma

I'm a journalist who loves this beat. I am not a pilot.

gaunt796 karma

What are your thoughts on safety self-certification as a general process? Can regulatory agencies and manufacturers be trusted with this responsibility?

seattletimesnewsroom26 karma

It is actually necessary to have a huge element of the certification done by the manufacturer, in this case Boeing. The true subject matter experts who are working at the cutting edge of whatever the technology is are inside the company. The government engineers within the FAA don't have the same expertise.

However, that said, it seems to me that the crucial element is then independent oversight of Boeing's certification work. That seems to have been inadequate in the case of the MAX and indeed even in the case of the previous new jet, the 787.

FAA oversight needs tightened. The pressured atmosphere within the FAA, with managers pushing to meet Boeing's schedule, which I described in this story, is not the way to ensure safe , independent oversight.

mxgsfmdpx3 karma

Are the MAX planes still currently grounded? When do they expect to be back in the air? Thanks!

seattletimesnewsroom5 karma

Still grounded. Unclear when they will get clearance to fly again. Boeing is hoping early summer. Outside observers are thinking late summer or early fall.

victoryvice3 karma


seattletimesnewsroom16 karma

I haven't come across anything similar. And I have to say that I struggle to understand the design decisions on that flight control system. The biggest mystery is why it was designed to be activated by a single sensor. I haven't heard any plausible explanation from Boeing.

thelostandfoundkid2 karma

Is it all this started because Boeing shifted the engine upwards to accommodate for a bigger engine?

seattletimesnewsroom7 karma

The need to shift the engines did change the flight characteristics and that in turn led to the need for this MCAS flight control system.

But as mentioned in a previous answer, I don't think there was anything inherently unsafe about moving the engines.

imnotsoho1 karma

From what I understand they are still building the Max. Is that in Renton? How much room do they have for more planes, or are they allowed to fly them without passengers?

seattletimesnewsroom3 karma

They can fly them without passengers. The planes are stacking up around the Puget Sound region. If they run out of room here, Boeing could fly them to Moses Lake in eastern Washington.

Preseli0 karma

Is this a case of Boeing resting on it's laurels as the near-monopoly leader of aviation?

seattletimesnewsroom12 karma

Boeing is not "the near-monopoly leader of aviation"!

Airbus is on a par with its U.S. counterpart. And Boeing is extremely aware of that and very far from resting on its laurels has been working hard to compete.

Boeing is generally ahead in the category of big widebody jets, but Airbus has been beating it in the marketplace for single-aisle jets. That's why the MAX was developed: because of the runaway success of the A320neo and especially the A321neo.

clemtiger2011-1 karma

How much Schadenfreude is there around Seattle over this, since they left for the new, non-union plant in Charleston, SC?

seattletimesnewsroom25 karma

None. Everyone here, especially Boeing employees, feels gut-wrenched about these tragedies.

Empigee-3 karma

Why is this story getting relatively little public outrage despite the number of deaths involved?

seattletimesnewsroom4 karma

I don't know what you mean. There's been a massive reaction.