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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

#321

Post by jetrink »

userbinator wrote: post #314
caconym_ wrote: post #306

Earlier quoted context omitted.

There is a difference between proactively pursuing safety, which will yield diminishing returns sooner or later, and acting to correct a known defect that puts human lives at risk via a clearly understood mechanism.

You could say that everything is a known defect. Pilots can make fatal mistakes or just become suicidal, all the engines could be overwhelmed by birds, etc. The argument against that is, succinctly, "life is a risk." Humans do things all the time with the full knowledge that what they're doing could kill them.

But we attempt to mitigate the risks you cited as well. Engine designs are subjected to bird ingestion tests. Controls and procedures are designed to reduce the chance that pilots will make serious errors. Pilots can be ordered to undergo psychological testing by an FAA-approved physician if they show signs of mental health issues. Etc.

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

#322

Post by pizza »

dabbledash wrote: post #297
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. -…

What is the alternative to a cost benefit analysis though? We could spend an infinite amount on diminishing safety gains.

No one is saying to use something other than a cost benefit analysis; they are saying make sure that the costs are actually priced accurately, and to err on the side of caution when estimating the damages you can cause.

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

#323

Post by andrewflnr »

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...

HN likes to link as closely to the original source as possible, which in this case looks like the imgur album rather than the reddit thread linking to it. It's probably not personal, just a de-noising instinct gone awry.

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

#324

Post by theptip »

dabbledash wrote: post #297
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. -…

What is the alternative to a cost benefit analysis though? We could spend an infinite amount on diminishing safety gains.

A cost-benefit analysis is appropriate, but the "cost" side should be QUALYs not literal litigation costs.

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

#325

Post by skookumchuck »

cco wrote: post #212
stcredzero wrote: post #83

Earlier quoted context omitted.

Boeing's more general attitude of dismissing signs that there was a problem with the equipment Having worked in software for decades, I've noted a particular sort of bias in myself and other developers. We tend to feel that our creations are like our children, and we are far too ready to blame the user. I've caught myself doing this. I've been caught out by QA doing this. I've caught fellow developers doing this, whe…

In my experience end users are very often wrong, QA departments are rarely wrong. If pilots are saying I pressed the rudder and it didn't move healthy skepticism may be needed, I'd hazard less skepticism than for an average end user as the pilots are presumably highly skilled users of the product. But if after very thorough investigations a large group of pilot reports and the NTSB are telling you something is wrong…

The cases of "surging" where people claimed they were pressing hard on the brake when the car lept forward come to mind. (The most credible explanation is they put their foot on the gas instead, or are simply trying deflect blame away from themselves for the crash.)

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

#326

Post by skookumchuck »

nerpderp82 wrote: post #278
stcredzero wrote: post #176

Earlier quoted context omitted.

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.

I recall a kids game where the game exited when the spacebar was touched. It was pretty exasperating, because the kiddies couldn't figure out how to get the game running again.

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

#327

Post by dabbledash »

theptip wrote: post #324
dabbledash wrote: post #297

Earlier quoted context omitted.

What is the alternative to a cost benefit analysis though? We could spend an infinite amount on diminishing safety gains.

A cost-benefit analysis is appropriate, but the "cost" side should be QUALYs not literal litigation costs.

I’d slightly tweak this and say legal liability should be calculated using QUALY. The idea is to shift the financial burden on the right party so they’ll be incentivized to do the CBA correctly. They’re not going to internalize costs out of the goodness of their hearts.

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

#328

Post by LeoPanthera »

Admiral_C wrote: post #268
coryfklein wrote: post #266

Earlier quoted context omitted.

Out of curiosity, does Imgur not allow you to modify the text passages in the album after you create it? If it does and I was the author, I would certainly be putting my name/username and a link to the Reddit post in there!

Since I'm not logged in to Imgur when I post the albums, it allows me to modify the text only within 12 hours after posting. This annoys me a lot but I've yet to find a better platform that has all the attributes I want. (I don't want to make an account and actually upload it there because then I'm submitting it to an audience that I have no intention of engaging with and know nothing about.)

Even if you are logged in, uploaded content isn't shown to the Imgur "community" unless you choose to "share" it.

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

#329

Post by dang »

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...

I've put that link at the top and mentioned your username. If there's something else we can do to credit you, let us know.

I briefly changed the submission to point to that URL, but Jolter has a good point too: https://news.ycombinator.com/item?id=19394058.

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

#330

Post by jerquee »

dabbledash wrote: post #297
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. -…

What is the alternative to a cost benefit analysis though? We could spend an infinite amount on diminishing safety gains.

you're forgetting that the numbers are skewed by the concealment of information by the manufacturer. If there were no secrets, the public would boycott airplanes with known problems like this one, and the cost comparison would be more appropriate.
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