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Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

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Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#121

Post by _pmf_ »

adrianN wrote: post #106
antihero wrote: post #84

Earlier quoted context omitted.

> to avoid recertification they kept their old computer hardware from earlier 737 generations, This is unbelievably fucked

No, it's not. Certification is an extremely expensive process with dubious benefits for safety. Why would you change hardware that has worked fine if it can fulfill your requirements?

That's related to an issue often found in medical devices development: the certified toolchain contains errors, but you cannot use the newer version with fixed errors because it is not certified. Of course, the new toolchain passes the same certification suite as does the faulty one (because the certification body does only check the documentation for completeness and basic plausibility and does not have any means to test anything themselves), it's just that it isn't commercially viable to "buy the official stamp".

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#122

Post by ethbro »

CydeWeys wrote: post #101
ethbro wrote: post #86

Earlier quoted context omitted.

I love how HN is taking umbrage in the rest of the comments about Boeing being too aggressive with MCAS et al. redesign. Then taking umbrage here that they were too conservative and possibly froze the hardware spec.

The general consensus I've seen here on HN is that Boeing should have done a clean sheet design rather than trying to shoehorn increasingly ill-fitting features into a decades-old design. You're not accurately representing that view.

http://news.aa.com/news/news-details/2011/AMR-Corporation-An...

"American also intends to order 100 of Boeing's expected new evolution of the 737NG, with a new engine that would offer even more significant fuel-efficiency gains over today's models. American is pleased to be the first airline to commit to Boeing's new 737 family offering, which is expected to provide a new level of economic efficiency and operational performance, pending final confirmation of the program by Boeing. This airplane would be powered by CFM International's LEAP-X engine."

When a customer demands...

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#123

Post by Someone1234 »

I'm surprised nobody is discussing this paragraph from the article:

> The failure scenario was known previously and had been assessed in a safety analysis when the plane was certified before entering service in 2017. At that time, Boeing concluded that pilots could overcome the nose-down movement by performing a procedure to shut off the motor driving the stabilizer movement.

This isn't a new fault. Boeing certified this as safe along with MCAS back when the aircraft first flew in 2017, using the same justifications ("pilots can overcome it").

They weren't going to fix it this time either, except test pilots ran across it in late-stage simulations monitored by the FAA and found it wasn't as easy to overcome as Boeing had been asserting in their cost-safety analysis (just like MCAS) and now the FAA are requiring a fix.

Has Boeing learned anything from MCAS? The company has cultural problems vis-à-vis safety. I'm just glad the FAA are doing their job this time around.

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#124

Post by tolien »

alexis_fr wrote: post #25
xvf22 wrote: post #6

Earlier quoted context omitted.

It's one of those fixes where they add up the value of human life if something goes wrong and say 'OK we can handle that, ship it"

I wonder if the human life calculation worked well this time. As far as I see, Boeing lost more than the sum of the human lives; they also lost reputation for everything new they’ve designed in the last 7 years being corrupted, and they also engulfed the reputation of FAA with them, whose agents would fit the definition of “corrupted” by any people’s definition (I know, they are not, they just used agents of Boeing t…

DeHavilland didn’t do that badly - the last Nimrod (based on the Comet) was retired in 2011. The name disappeared because, like a whole host of British aviation manufacturers (English Electric, Folland, Vickers, Supermarine, Hawker-Siddeley, Bristol, Hunting, Avro), they successively merged together until all that was left was a name you probably are familiar with - BAE Systems.

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#125

Post by JustSomeNobody »

adrianN wrote: post #106
antihero wrote: post #84

Earlier quoted context omitted.

> to avoid recertification they kept their old computer hardware from earlier 737 generations, This is unbelievably fucked

No, it's not. Certification is an extremely expensive process with dubious benefits for safety. Why would you change hardware that has worked fine if it can fulfill your requirements?

If the requirements were for it to buck like a bronco before slamming into the ground then I say job well done.

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#126

Post by raverbashing »

wiz21c wrote: post #107
raverbashing wrote: post #74

Earlier quoted context omitted.

I can understand it looks weird but it isn't. A faster processor has no more real time guarantees than a slower processor from the 80s Of course, the faster one can do more stuff in less time, but for flying an airplane (or going to the moon) the amount of computing power needed is much less than people imagine. The issue here is adding more computing into an aging platform. But there's nothing inherently wrong into…

is it me or the certification looks at the hardware but not at the software ?

Certification mostly looks at the behaviour, how you get there is your IP for the most part

For example, the regulator doesn't care (much) how you built your wing, but it does care that's able to withstand 150% of the maximum expected forces.

You can have parts done by different manufacturers (but to the same spec) and this is sometimes done on purpose in redundancy settings so that unknown bugs in one model are less likely to show up in a different model.

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#127

Post by acqq »

DanHulton wrote: post #110
zerogvt wrote: post #59

Earlier quoted context omitted.

When your design is a mess you're probably better off to scrap it altogether and start from a clean piece of paper. "Fixes" to a bad design are adding to the mess. And in this case the mess has already cost hundreds of lives. You cannot "patch" this...

I see this sentiment a lot, but its kind of surprising. Traditional wisdom states the opposite - never do a full rewrite, you lose the years of buit-up fixes and edge cases and have to learn from scratch in too many places. Despite everything, I still don't think the solution to the 737 MAX problem is to start over. The base problem that Boeing has its actually their terrible engineering culture, the one that values…

The problem here is that what Boeing is selling ("737 that spends significantly less fuel and doesn't need recertification") simply can't be made safe. Whatever results from the marketing driven goal (selling something that doesn't and can't exist in reality) will remain unsafe as long as all the "already sold features" are preserved.

So it's not if they should "start from clean" but just accept the need for the new certification and then do the changes that are really needed. It will be less profitable for Boeing but it righly should be this time! They are killing people otherwise.

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#129

Post by linuxftw »

Someone1234 wrote: post #123

I'm surprised nobody is discussing this paragraph from the article: > The failure scenario was known previously and had been assessed in a safety analysis when the plane was certified before entering service in 2017. At that time, Boeing concluded that pilots could overcome the nose-down movement by performing a procedure to shut off the motor driving the stabilizer movement. This isn't a new fault. Boeing certified…

The FAA is only doing their job this time around because the rest of the entire planet, literally, was grounding the aircraft while the FAA baselessly stated the aircraft was safe. This is all stuff that should have been investigated after the first crash, not the second.

Has Boeing learned anything? Of course not. There are no executives facing jail time, or even fines! They're shameless frauds that outsourced their critical systems to the lowest bidder with predictable results.

Re: Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software

#130

Post by tim333 »

NeedMoreTea wrote: post #102
jacobush wrote: post #55

Earlier quoted context omitted.

There is so much of U.K. which is incredible and depressing at the same time. Completely pummelled by war, (receiving no aid like West Germany did) they managed to, in 1949, release a Space Age passenger commercial airliner, defining the genre. It looks modern even today. Yet, fumbled the ball. They also had a space program, closed it down after their first satellite, which was a success. Concorde! (With France.) It…

TSR2, Hawker P.1154 (Supersonic Harrier) Royal Aircraft Establishment - merged and amalgamated a dozen times to become DERA - privatised. Now QinetiQ. Most of the decent research sites are gone now. GEC/Plessey I'm going to stop now, it'll get depressing.

Dyson were doing quite well till Mr Dyson went pro brexit and moved the company to Sinagpore.
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