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Rudder issue that plagued the Boeing 737 throughout the 1990s

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Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#271

Post by jfk13 »

smsm42 wrote: post #201
jfk13 wrote: post #114

Earlier quoted context omitted.

Sure. But the Ray Miller quote suggests that the issue was not that a modification to make the rudder mechanism more reliable was itself prohibitively expensive from an engineering point of view. Rather, the concern was that making such a modification could open up liability issues, as it would be an acknowledgement that the plane was faulty, and the FAA and Boeing were anxious to avoid being held liable. That is wha…

This looks like a system set up for catastrophic failures. I mean, if everybody involved that has means and knowledge to do anything about safety faults has a huge incentive to not do anything about them, how we expect not to have very bad outcomes? I think it'd be smart to move on from "boo selfish people, how could they!A" to "we must redesign the system so people are not hugely disincentivized from doing the thing…

Sure. It seems to me that if a company has followed established "good practices" for design and engineering in its field, and the appropriate checks and approvals have been granted, this should go a long way to mitigate its liability for unforeseen problems that may later appear, despite the good intentions and best efforts of all concerned.

This may well be applicable to the earliest B737 rudder incidents, for example.

Acting to rectify the (previously unsuspected) fault should not increase the company's liability for a problem it was unable to anticipate.

But once a problem has been discovered/reported, if the company does not act to rectify it in a timely way, its liability for any further problems that occur should rise rapidly. And once several serious in-flight emergencies related to the B737 rudder had occurred, it seems (judging by the story as presented here) like Boeing was probably guilty of this and should be severely penalized.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#272

Post by js2 »

spiznnx wrote: post #261
js2 wrote: post #258

Earlier quoted context omitted.

Don't pay attention to the news. It reports statistically rare events that are unlikely to affect you. Pay attention to the statistics[0,1,2]. US aviation is still remarkably safe[3]. Just don't be this guy[4]. [0] http://ipa-world.org/society-resources/code/images/95b1494-L... [1] https://www.cdc.gov/nchs/fastats/leading-causes-of-death.htm [2] https://www.bls.gov/iif/oshcfoi1.htm [3] https://en.wikipedia.org/wiki/A…

I'm not worried personally about flying on this plane, I wouldn't change my plans to avoid it. I just had held a very high opinion of the engineering discipline and regulatory practices that has been suddenly re-evaluated.

We've come a long way though and I'd still rather take my chances with today's engineering discipline and regulatory practices than say, a saber toothed tiger.

I think these sorts of missteps always have and always will occur, and yet in the grand scheme of things, we build remarkably safe systems. If you look at any man-made disaster, you're almost always going to find the same sorts of things that led to the Boeing rudder issue. I'm sure you're familiar with the Citicorp Tower story:

http://www.slate.com/blogs/the_eye/2014/04/17/the_citicorp_t...

https://en.wikibooks.org/wiki/Professionalism/William_LeMess...

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#273

Post by mschuster91 »

Sohcahtoa82 wrote: post #263
syn0byte wrote: post #221

Earlier quoted context omitted.

And MrHands[0] was a Boeing engineer. Over extending rods indeed... 0) Nope.

In case anyone hasn't heard of Mr. Hands and is wondering why syn0byte didn't provide a citation... It's extremely NSFW. Suffice to say, a man and a horse are involved, and the man did not survive. Google/Duck it at your own risk.

Seriously wtf is wrong with some people. Googling for this is indeed... risky.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#274

Post by marcosdumay »

DuskStar wrote: post #170
marcosdumay wrote: post #125

Aviation has an well known acceptable risk level at around 10^-9 for each issue. That's the number that leads government intervention, pilot procedure designing, aircraft designing and everything else. It's expected to lead to a less than 10^-6 chance of accidents per flight. (Somebody calculated the B783 Max odds on 4*10^-6 yesterday, what is a crazy high level.) That number has been higher in the past, and is movin…

> Somebody calculated the B783 Max odds on 4*10^-6 yesterday, what is a crazy high level. I think that may have been me (1/250000), but that was based on a couple of generous assumptions - two crashes across 4 flights/day on 350 planes for an average of 365 days. Unfortunately I think a more reasonable flights/day number is 3 or lower - a lot of Max 8s are on longer routes - and the flight day average is almost certa…

A few years ago I calculated with a friend the accident rate of several cohorts of Brazilian aviation (well, the part of aviation that operates on aerodromes, so no agriculture or sports). Our worst cohort was for private planes, private pilots, on small airports, on fast growing cities. It was just a little bit under 4*10^-6 accidents (all, not only fatal) per airport operation (that is, twice your number).

I was really scared by your number. I wouldn't ever jump into a random private plane, and seems that people refusing to jump into a B733 Max (looks like I wrote it wrong earlier) are doing a reasonable thing.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#275

Post by Jolter »

Admiral_C wrote: post #256

I wrote this, not happy it got picked up and posted here without credit. Here's the original Reddit thread: https://www.reddit.com/r/CatastrophicFailure/comments/adl0jk...

To a HN reader, posting the Reddit thread would have been less useful than the imgur album, because the reader would have to click through to the album. Maybe you should edit the album and link it back to the reddit thread?

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#276

Post by madez »

JoshuaRLi wrote: post #267

> A new car built by my company leaves somewhere traveling at 60 mph. The rear differential locks up. The car crashes and burns with everyone trapped inside. Now, should we initiate a recall? Take the number of vehicles in the field, A, multiply by the probable rate of failure, B, multiply by the average out-of-court settlement, C. A times B times C equals X. If X is less than the cost of a recall, we don't do one. -…

That first approximation is only valid for small total numbers of failures. If a failure repeats, the loss function is not simply A times B times C but greater, for example by loss of perceived quality of products, or by criminal investigations against the company and individuals in it.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#277

Post by marcosdumay »

Lorkki wrote: post #197
DuskStar wrote: post #170

Earlier quoted context omitted.

> Somebody calculated the B783 Max odds on 4*10^-6 yesterday, what is a crazy high level. I think that may have been me (1/250000), but that was based on a couple of generous assumptions - two crashes across 4 flights/day on 350 planes for an average of 365 days. Unfortunately I think a more reasonable flights/day number is 3 or lower - a lot of Max 8s are on longer routes - and the flight day average is almost certa…

Also, I believe the statistic of interest here is incidents per operating hour, not per flight?

All of accidents per hour, accidents per operation, and fatality per passenger are relevant.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#278

Post by nerpderp82 »

stcredzero wrote: post #176
usrusr wrote: post #161

Earlier quoted context omitted.

The effect of dogfooding is limited though: when you know all the quirks you won't when notice that you constantly work around them.

when you know all the quirks you won't when notice that you constantly work around them. Unfortunately, we programmers are particularly good at doing this. We are extremely good at being "nice" to software. ("Mechanical sympathy")

My child has bypassed the lock screen on my laptop and caused a gray-screen-of-death, just by banging on the keyboard. I saw it, I am unable to replicate it. Everything should be tested by a child before it can enter production service.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#279

Post by testvox »

why-el wrote: post #238
gameswithgo wrote: post #222

Earlier quoted context omitted.

I wonder what solutions there are to these liability/blame problems. I have seen a similar case in Australia, where a parking barrier was an extreme danger as it cross over a biking path, and was hard to see until the last minute. It caused a crash that took a mans leg, and the legal proceedings took years. During that time the barrier remained in place, still a danger, because removing it would have admitted fault.

What was the result of the litigation? From a money perspective, it seemed like "admitting fault" would be far more reasonable, and I think in this sense executives tend to exaggerate effects of "admitting fault", because, in the end, they are betting that legal proceedings would nullify its effects, but as we are learning now, it's not the case at all. Public memory might be short, but it regenerates at alarming spe…

They might have not been contractually allowed to admit fault. Many insurance policies do not allow the insured to admit fault, or they forfeit the policy.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#280

Post by Admiral_C »

Jolter wrote: post #275
Admiral_C wrote: post #256

I wrote this, not happy it got picked up and posted here without credit. Here's the original Reddit thread: https://www.reddit.com/r/CatastrophicFailure/comments/adl0jk...

To a HN reader, posting the Reddit thread would have been less useful than the imgur album, because the reader would have to click through to the album. Maybe you should edit the album and link it back to the reddit thread?

Can't edit the albums more than 12 hours after posting unfortunately, take it up with Imgur's website design department lol. I didn't expect these to be read off of Reddit so I didn't make that convenient (until recently).
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