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A Matter of Millimeters: The story of Qantas flight 32

admiralcloudberg.medium.com

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Re: A Matter of Millimeters: The story of Qantas flight 32

#151

Post by blauditore »

modernpacifist wrote: post #40

I don't know about others, but I can't help but smile when I read the detailed series of events in aviation postmortems. To be able to zero in on what turned out to be a single faulty part and then trace the entire provenance and environment that led to that defective part entering service speaks to the robustness of the industry. I say that sincerely since mistakes are going to happen and in my view robustness has l…

This kind of makes sense, but it is only possible because of public pressure/interest. Many people are irrationally emotional about flying (fear, excitement etc.), that's why articles and documentaries like this post are so popular.

On a side note, that's also why there's all the nomsense security theater at airports.

Re: A Matter of Millimeters: The story of Qantas flight 32

#152

Post by lloeki »

WalterBright wrote: post #65
modernpacifist wrote: post #40

I don't know about others, but I can't help but smile when I read the detailed series of events in aviation postmortems. To be able to zero in on what turned out to be a single faulty part and then trace the entire provenance and environment that led to that defective part entering service speaks to the robustness of the industry. I say that sincerely since mistakes are going to happen and in my view robustness has l…

As a former Boeing engineer, other industries can learn a great deal from how airplanes are designed. The Fukushima and Deepwater Horizon disasters were both "zipper" failures that showed little thought was given to "when X fails, then what?" Note I wrote when X fails, not if X fails. It's a different way of thinking.

When I worked in an industrial context, some coding tasks would seem trivial to today's Joe Random software dev, but we had to be constantly thinking about failure modes: from degraded modes that would keep a plant 100% operative 100% of the time in spite of some component being down, to driving a 10m high oven has the opportunity to break airborne water molecules from mere ambient humidity into hydrogen whose buildups could be dangerously explosive if some parameters were not kept in check, implying that the code/system has to have a number of contingency plans. "Sane default" suddenly has a very tangible meaning.

Re: A Matter of Millimeters: The story of Qantas flight 32

#153

Post by asystole »

WalterBright wrote: post #65
modernpacifist wrote: post #40

I don't know about others, but I can't help but smile when I read the detailed series of events in aviation postmortems. To be able to zero in on what turned out to be a single faulty part and then trace the entire provenance and environment that led to that defective part entering service speaks to the robustness of the industry. I say that sincerely since mistakes are going to happen and in my view robustness has l…

As a former Boeing engineer, other industries can learn a great deal from how airplanes are designed. The Fukushima and Deepwater Horizon disasters were both "zipper" failures that showed little thought was given to "when X fails, then what?" Note I wrote when X fails, not if X fails. It's a different way of thinking.

I agree in principle, but I don't think industries should be looking at current-day Boeing's engineering practices except for an example of how a proud company's culture can rot from the inside out with fatal consequences.

Re: A Matter of Millimeters: The story of Qantas flight 32

#154

Post by asystole »

cedivad wrote: post #112
WalterBright wrote: post #65

Earlier quoted context omitted.

As a former Boeing engineer, other industries can learn a great deal from how airplanes are designed. The Fukushima and Deepwater Horizon disasters were both "zipper" failures that showed little thought was given to "when X fails, then what?" Note I wrote when X fails, not if X fails. It's a different way of thinking.

> When my AoA sensor fails, then what? crickets, let's just randomise which sensor we use during boot, that ought to do it!

> Airlines really want to be able to use pilots' existing type-rating on this hulking zombie of a 60s-era airframe with modern engines but it behaves differently under certain conditions, what do we do?

let's just build a system that pushes the nose down under those conditions, have it accept potentially unreliable AoA data, and not tell pilots about it!

Re: A Matter of Millimeters: The story of Qantas flight 32

#155

Post by inglor_cz »

nextos wrote: post #58
modernpacifist wrote: post #40

I don't know about others, but I can't help but smile when I read the detailed series of events in aviation postmortems. To be able to zero in on what turned out to be a single faulty part and then trace the entire provenance and environment that led to that defective part entering service speaks to the robustness of the industry. I say that sincerely since mistakes are going to happen and in my view robustness has l…

Aviation is great because the industry learns so much after incidents and accidents. There is a culture of trying to improve, rather than merely seeking culprits. However, I have been told by an insider that supply chain integrity is an underappreciated issue. Someone has been caught selling fake plane parts through an elaborate scheme, and there are other suspicious suppliers, which is a bit unsettling: "Safran conf…

I suspect this is precisely what is happening in Russian civil aviation now. No legit parts supplied, so there will be a lot of fake/problematic parts imported through black channels.

Re: A Matter of Millimeters: The story of Qantas flight 32

#156

Post by liendolucas »

It's so interesting to read on aviation postmortems even for people that don't fully understand all the technical details as explained in the article (great by the way, kudos to the author). I've always wondered if there is an authoritative database with all significant events in aviation to read and learn more about? Do pilots study past events as part of their training?

Re: A Matter of Millimeters: The story of Qantas flight 32

#157

Post by magicalhippo »

f1shy wrote: post #120
WalterBright wrote: post #65

Earlier quoted context omitted.

As a former Boeing engineer, other industries can learn a great deal from how airplanes are designed. The Fukushima and Deepwater Horizon disasters were both "zipper" failures that showed little thought was given to "when X fails, then what?" Note I wrote when X fails, not if X fails. It's a different way of thinking.

As an engineer I think a lot about tradeoffs of cost vs other criteria. There is little I can learn from nuclear or aviation industry, as the cost structure ist so completely different. I’m very happy that the costs of safety in aviation are very good accepted, but I understand that few people are willing to pay similar costs for other things like, say, cars.

We're making a niche B2B application, and this is very much it for us as well.

Our customers are in a cutthroat market with low margins. We can't spend a ton on pre-analysis, redundancies and so on.

Instead we've focused reduced the impact of failures.

We've made it trivial to switch to an older build in case the new one has an issue. Thus if they hit a bug they can almost always work around it by going to an older build.

This of course requires us to be careful about database changes, but that's relatively easy.

Re: A Matter of Millimeters: The story of Qantas flight 32

#158

Post by otherme123 »

abid786 wrote: post #49
sylens wrote: post #42

Earlier quoted context omitted.

I think many of us are so used to working with software, with its constant need for adaptation and modification in order to meet an ever growing list of integration requirements, that we forget the benefits of working with a finalized spec with known constants like melting points, air pressure, and gravity.

Completely agree - I think it can go one of two ways. Software is more malleable than airplanes are and that also comes with downsides (like how much time and effort it takes to bring a new plane to the market)

The article talks about a piece of software that partially failed, when they needed to calculate the braking distance for the overweight aircraft.

Re: A Matter of Millimeters: The story of Qantas flight 32

#159

Post by bambax »

Syzygies wrote: post #18

I am addicted to a fault to Mentour Pilot's studies of flight incidents. Again, here, he goes into greater depth: https://www.youtube.com/watch?v=JSMe1wAdMdg

I like Mentour Pilot but the outcome of the incident is only revealed at the end.

Admiral Cloudberg's articles are more like Columbo: they start with what happened, and then go back in time to find out and explain all the little details that caused it. In a way it's much more logical that way.

Mentour Pilot constantly has to say "remember this, it will prove important later". But we don't know why it's important, and so we don't remember, and as a result the narrative is much less clear.

Re: A Matter of Millimeters: The story of Qantas flight 32

#160

Post by danhor »

masklinn wrote: post #135
uselpa wrote: post #126

Earlier quoted context omitted.

Cars might not be the best example, since human lives are at stake, as in aviation. Unless you work on Teslas autopilot, it seems. But yes, backups and restores are often good enough.

As it turns out (and as much as we wouldn’t want them to) human lives are still subject to cost/benefit analysis. An airliner is a lot of lives, a lot of money, a lot of fuel, and a lot of energy. Which is why a lot has been invested in training, procedure, and safety systems. Cars operates in an environment which is in most ways a lot more forgiving, they’re controlled by (on average) low-training low-skill non-redu…

I wouldn't say it's simply cost-benefit analysis. It's also scale of accidents.

A whole lot more people die from car accidents, yet there are few reports on national news on accidents. So fewer people care. Meanwhile each time there is an aviation disaster, 100s of people die and it's all over the news for weeks. Similarly with train accidents and nuclear accidents. There where only 2 very large ones but they still haunt the field to this day, while (for example) the deaths from solar installations by people falling from roofs are mostly ignored.

Large accidents have to be avoided, a lot of small ones are more acceptable.

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