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Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

nytimes.com

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Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#101

Post by mehrdadn »

csours wrote: post #97
mehrdadn wrote: post #46

Earlier quoted context omitted.

I don't see these as equivalent, at least not based on what I've learned about the cases (feel free to correct). As I understand, Therac-25 was due to software bug and a genuine design process inadequacy that allowed it to cause a problem, that could happen with people acting entirely in good faith, simply because they didn't know better. That's why they created standards to address the design process. With 737MAX...…

It's not the equivalent, but it is the consequence of a chain of incremental changes, each of which is not sufficient to subvert safety margins, but together they change the paradigm. As to bad faith, yes, I'm sure there was some of that, but generally decisions like these don't look like bad faith to the people making them. It's easy to get swamped by technical details.

> consequence of a chain of incremental changes

> As to bad faith, yes, I'm sure there was some of that

You're downplaying this. This is not downplayable, and this is not similar to Therac. "A consequence of incremental changes" is a rather gross way to paint this, as if it's hard for a single guy to see how e.g. non-redundant sensors is an extremely bad idea on its own, let alone everything else. There have been multiple huge missteps, not made by accident, each of which is individually worth a huge red flags obvious to people in different areas. That 1 single mistake wasn't enough to bring the plane down doesn't mean the mistakes must've been small or somehow downplayable. And no, this isn't some kind of gray area with people getting genuinely swamped by technical details. It's abundantly clear here's been a ton of bad faith here, that there is still ongoing bad faith even after the fact, and that they're still unwilling to address the problem properly.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#102

Post by csours »

mehrdadn wrote: post #101
csours wrote: post #97

Earlier quoted context omitted.

It's not the equivalent, but it is the consequence of a chain of incremental changes, each of which is not sufficient to subvert safety margins, but together they change the paradigm. As to bad faith, yes, I'm sure there was some of that, but generally decisions like these don't look like bad faith to the people making them. It's easy to get swamped by technical details.

> consequence of a chain of incremental changes > As to bad faith, yes, I'm sure there was some of that You're downplaying this. This is not downplayable, and this is not similar to Therac. "A consequence of incremental changes" is a rather gross way to paint this, as if it's hard for a single guy to see how e.g. non-redundant sensors is an extremely bad idea on its own, let alone everything else. There have been mul…

I'm sorry that it seemed like I was downplaying it.

What I was actually thinking is that this kind of thing is likely to crop up in complex systems, and if we work on complex systems we should be wary for it.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#103

Post by danols »

ilaksh wrote: post #98
danols wrote: post #85

The day someone very high up the corporate ladder truly gets held responsible for this type of greed & negligence and will be put a way for a long prison sentence would be a good day for society. But I am not holding my breath... But I hope that the CEO Dennis Muilenburg deep down understands he seriously fuxxed up real bad and every now and then is having a hard time falling a sleep in his $10M mansion knowing that…

I agree. I think the FAA failed in it's mission also.

Their credibility outside the US is shattered. Their word & opinion caries zero weight anymore since they have proven themselves to be morally corrupt.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#104

Post by nopzor »

na85 wrote: post #99
inferiorhuman wrote: post #89

Earlier quoted context omitted.

In what world is scrapping the airframes due to a (serious) software fault the best and most sensible solution? A world in which the faulty software was required to fix faulty hardware.

The hardware isn't faulty. The problem is the way Boeing tried to achieve a zero training delta so pilots wouldn't have to get a second type rating.

the airplane did not have stable flight characteristics because of its physical design.

that’s a hardware problem.

MCAS only exists because of that hardware problem.

the fact that boeing also did not train or tell pilots about MCAS, in order to make the airplane more financially appealing by retaining the 737 type rating, is a separate (also bad) issue.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#105

Post by KaoruAoiShiho »

How would you design your bureaucracy so that this kind of thing can't happen? I see this type of failure all the time in organizations big and small. Sometimes things are just too complex to have an auteur that can understand the entire system and when every department strives to optimize for its specific goal shit can really hit the fan.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#106

Post by nopzor »

ilaksh wrote: post #98
danols wrote: post #85

The day someone very high up the corporate ladder truly gets held responsible for this type of greed & negligence and will be put a way for a long prison sentence would be a good day for society. But I am not holding my breath... But I hope that the CEO Dennis Muilenburg deep down understands he seriously fuxxed up real bad and every now and then is having a hard time falling a sleep in his $10M mansion knowing that…

I agree. I think the FAA failed in it's mission also.

it’s reputation has been destroyed in the international aviation community.

which is extremely sad because it was really hard won.

classic story of gutting a gov organization, and regulatory capture.

i know some really good people at faa and the situ makes their blood boil. mine too.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#107

Post by na85 »

nopzor wrote: post #104
na85 wrote: post #99

Earlier quoted context omitted.

The hardware isn't faulty. The problem is the way Boeing tried to achieve a zero training delta so pilots wouldn't have to get a second type rating.

the airplane did not have stable flight characteristics because of its physical design. that’s a hardware problem. MCAS only exists because of that hardware problem. the fact that boeing also did not train or tell pilots about MCAS, in order to make the airplane more financially appealing by retaining the 737 type rating, is a separate (also bad) issue.

>the airplane did not have stable flight characteristics because of its physical design.

This is a gross oversimplification of the problem. In most of the flight envelope the aircraft is stable.

At high alpha the aircraft has pitch problems.

There are myriad ways to address this, and MCAS was one (bad) choice of many available to Boeing.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#108

Post by soundpuppy »

Airplanes have become next to impossible to maintain, mostly software related, yet at the same time seem to be increasingly available to only the rich. Oh what a tragedy.

And if you don't believe me, why are we doing this passport only to certain individuals I heard of?

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#109

Post by gmueckl »

HarryHirsch wrote: post #20
mikeash wrote: post #4

Earlier quoted context omitted.

The problem isn’t failure, but detecting failure. If the sensor had just stopped responding, there wouldn’t have been any problem. The planes would keep flying, the sensors would get replaced, and everyone would be fine. What happened was that the sensor gave erroneous readings. The MCAS system reacted to those erroneous reading and crashes the plane. With two sensors, you can detect failure. It’s very unlikely that…

It’s very unlikely that both would fail simultaneously. Birgenair 301 crashed into the Atlantic because mud dauber wasps built nests in both pitot tubes while the plane was on the ground. It happens.

No, the accident report mentions only a failure of the air speed indicator on the pilot side. The copilot and backup indicators were working, but the crew failed to recognize that.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#110

Post by salawat »

kejaed wrote: post #27

I really see this as a failure of the Systems Engineering process. With so many people unaware of the impacts of the changes, it’s up to the systems types to have the big picture view and make sure these sorts of things are taken into account. Especially if as the article says a failure of the AOA sensor on the system would be Hazardous (looks like it was Catastrophic when paired with MCAS in retrospect), that would…

>Especially if as the article says a failure of the AOA sensor on the system would be Hazardous (looks like it was Catastrophic

From my understanding, this was an intentional decision, as the only way they could certify the airframe without simulator training being required was to feed the MCAS with only 1 sensor.

The only way they could do that is keeping the system overall rated as hazardous, as the Catastrophic rating would require multiple redundancy plus the training.

This can be corroborated from the Australian 60 minutes expose.

>For sure there may have been pressure from management to keep MCAS out of the manual but it’s not really up to he regulatory agency to be experts on the aircraft design, if things are being hidden by the company then I’d consider this bordering on professional misconduct on the parts of the engineers overseeing this work.

That is my conclusion as well.

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