Latest 737 Max Fault That Alarmed Test Pilots Rooted in Software • Hacker News Board

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

#101

Post by CydeWeys » Sat, Jul 27, 2019, 12:54 PM UTC

ethbro wrote: post #86

robin_reala wrote: post #81

Earlier quoted context omitted.

Can’t find the exact MIPS estimate for the Harris CS80C286 25Mhz 286, but given that the 1.5MIPS was quoted for the 10Mhz Intel one I’d guess it’s substantially faster. Although still slower than an Arduino :)

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.

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

#102

Post by NeedMoreTea » Sat, Jul 27, 2019, 1:00 PM UTC

jacobush wrote: post #55

alexis_fr wrote: post #25

Earlier quoted context omitted.

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…

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.

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

#103

Post by laythea » Sat, Jul 27, 2019, 1:00 PM UTC

pcl wrote: post #2

> Because the fault was triggered by specific streams of erroneous flight data, a new software patch can be devised that monitors the computer for that highly unusual condition and prevents movement of the stabilizer when it occurs, one of the people said. Oh man. That sounds like a mess.

It is.

But don't worry, when it is found out that it is a mess, we have a plan.

We can add a software patch to correct the bad software output. Not fix the bad software. But add some more to correct the output.

Genius!

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

#104

Post by LifeLiverTransp » Sat, Jul 27, 2019, 1:03 PM UTC

anticristi wrote: post #58

Before upgrading to the latest Ubuntu, I like to wait for a few months until my friends confirm that it's for the better. I guess I would do the same for the MAX. I can't imagine what it must be like to be one of the first pilots to fly the MAX once the grounding is lifted. Can pilots refuse to fly a specific plane "for a few months, 'cause I have kids waiting for me home"?

Goto take one for team "Cooperate Overlords".. but guess what - first class is going to be empty for a while. You can bring your family along -for free..

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

#105

Post by CydeWeys » Sat, Jul 27, 2019, 1:03 PM UTC

ethbro wrote: post #90

Aloha wrote: post #37

Earlier quoted context omitted.

Thats kinda my point, the shared type certificate is most of the justification for the airplane to exist, Boeing would rather build a whole new small aircraft, people who fly on them would rather fly on a whole new aircraft - airlines however strongly prefer something that costs as little as possible to put into service - and has commonality with existing fleets, which means not a whole new aircraft. I bet if you off…

And by "airlines", let's be specific: American Airlines was the carrier that specifically asked Boeing to build an 737 with new engines.

Although they didn't explicitly ask for such insane engineering compromises to have been made.

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

#106

Post by adrianN » Sat, Jul 27, 2019, 1:07 PM UTC

antihero wrote: post #84

aurelwu wrote: post #46

Earlier quoted context omitted.

The issue is (from what I understand as layman) that to avoid recertification they kept their old computer hardware from earlier 737 generations, and added more and more tasks to do for it. https://www.nytimes.com/2019/06/26/business/boeing-737-max-f... (somewhere in the middle: "The issue discovered last week is linked to the data-processing speed of a specific flight control computer chip, according to the two peop…

> 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?

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

#107

Post by wiz21c » Sat, Jul 27, 2019, 1:08 PM UTC

raverbashing wrote: post #74

jacobush wrote: post #51

Earlier quoted context omitted.

That's surreal - avionics should run on hard real time. (Whether it's offline scheduled and thus "impossible" to miss a deadline, or if it's "soft" realtime and merely testing ensures this, is not the important part. The important part is that it should never miss a deadline.)

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 ?

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

#108

Post by laythea » Sat, Jul 27, 2019, 1:11 PM UTC

Can anyone in the know explain why, if ground clearance due to the new engines is the issue, why Boeing cannot just add a few inches to the wheel stems?

This would raise the whole aircraft off the ground. Surely that wouldn't effect aerodynamics too much as the wheels are up most of the time.

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

#109

Post by adrianN » Sat, Jul 27, 2019, 1:14 PM UTC

king_magic wrote: post #99

std_throwaway wrote: post #94

Earlier quoted context omitted.

Closed source software should not be used in safety critical systems that affect the general public.

Most software engineers aren’t qualified to have an opinion about the quality of proprietary safety critical software systems that also happen to run against proprietary hardware. So unless you’ve found an economical way to develop an open source jetliner... honestly, what would be the point of open sourcing safety critical systems to the general public? I’m not at all saying it should be closed off from external saf…

You'd be surprised what fraction of a safety critical codebase is just mundane code that anybody can understand with the same amount of effort it takes for "normal" software. The real problem is that most outsiders don't understand the requirements very well (unless you make them public too!), so they can likely only find "simple" code quality issues.

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

#110

Post by DanHulton » Sat, Jul 27, 2019, 1:15 PM UTC

zerogvt wrote: post #59

pcl wrote: post #2

> Because the fault was triggered by specific streams of erroneous flight data, a new software patch can be devised that monitors the computer for that highly unusual condition and prevents movement of the stabilizer when it occurs, one of the people said. Oh man. That sounds like a mess.

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 shortcuts and profit over thoroughness and safety.

Even if they started from a blank piece of paper, they'd have that engineering culture problem (and to be fair, it is far more likely an engineering management culture problem), and they'd still turn out a design that kills people.