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A Matter of Millimeters: The story of Qantas flight 32

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

#301

Post by dghlsakjg »

WalterBright wrote: post #241
f1shy wrote: post #120

Earlier quoted context omitted.

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.

The costs of the Fukushima and Deepwater Horizon were very, very high. Both could have been averted at trivial expense with simple changes to the design. Fukushima: badthink - the seawall is high enough that it will stop tidal waves goodthink - what happens when the seawall is overtopped? Answer: the backup generators drown. Solution: put the backup generators on a platform. Deepwater Horizon: badthink - the pipe is…

This is so easy in retrospect when you know what the failure mode will be.

badthink: the Fukushima backup generators must be placed on a platform to keep them out of the range of a once in a millenium tsunami

goodthink: what happens when a typhoon comes and damages the generator on an exposed platform; an event which happens predictably and far more often than tsunamis. Answer: put the backup generators in the basement of a reactor building behind a large seawall. What catastrophe could put the reactor building completely underwater, and still have the reactor survive?

Yeah, trivial changes to the design can prevent all sorts of disasters, but you have to know what you are trying to prevent in a world of infinite complexity

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

#302

Post by sho »

WalterBright wrote: post #295
sho wrote: post #288

Earlier quoted context omitted.

Everything you said might well be true, and indeed as far as I know it is, but aircraft should not have fail-deadly systems which require lightning reflexes and up-to-the-second training to diagnose and disable fast enough before they crash the freaking plane in the first place. Yes, the pilots of the affected flights might have been able to save the aircraft if their training had been just that little bit better. We…

It did not require lightning reflexes or up-to-the-second training. The first LA crash came after the crew dealt with it for 11 minutes, and restored trim 25 times. The EA crew restored normal trim a couple times, and crashed after 3 minutes if I recall correctly. As for training, turning off the stab trim system to stop runaway trim is a "memory item", which means the pilots must know it without needing to consult a…

> Both Boeing and the crews share responsibility for the crashes.

And I never said they didn't. I just choose to assign Boeing the lion's share of the blame, as they should never have let that rush-job, cost-cutting death trap of a machine take to the skies in the first place.

Anyway, I see you have your mind made up, so there's not much point in arguing further. If you feel like continuing, why don't you take it up with - let's see - every single global aviation regulator, who also somehow came to the conclusion that there was maybe something a little bit wrong with the type.

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

#303

Post by airbreather »

lloeki wrote: post #152
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 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 buildu…

Yeah, I work as a Functional Safety Engineer in the process and machinery sector and 90%+ of effort is in planning, considering all the possibilities outside of intended operation and traceability.

I have worked on projects where in retrospect the LOC generated per day, if spread out across the whole project, were between 1 and 3.

But typically, writing of the code does not even commence in the first year, sometimes two.

Then there is the test cases and test coverage etc etc.

This is the difference between engineering code and just producing it - all the effort that goes into understanding all the unwanted code behaviour that may occur and how to detect, manage and/or avoid it.

Implicit state is the enemy, therefore the best code has all states explicitly defined.

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

#304

Post by oefnak »

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.

Are you serious in saying that other industries could learn from Boeing?

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

#305

Post by spurgu »

oefnak wrote: post #304
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.

Are you serious in saying that other industries could learn from Boeing?

He didn't actually say that.

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

#306

Post by bell-cot »

oefnak wrote: post #304
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.

Are you serious in saying that other industries could learn from Boeing?

Glancing at Walter Bright's brief Wikipedia page - I'd say he worked for Boeing well before they succumbed to the McDonnell Douglas Brain Fungus.

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

#307

Post by acyou »

dghlsakjg wrote: post #301
WalterBright wrote: post #241

Earlier quoted context omitted.

The costs of the Fukushima and Deepwater Horizon were very, very high. Both could have been averted at trivial expense with simple changes to the design. Fukushima: badthink - the seawall is high enough that it will stop tidal waves goodthink - what happens when the seawall is overtopped? Answer: the backup generators drown. Solution: put the backup generators on a platform. Deepwater Horizon: badthink - the pipe is…

This is so easy in retrospect when you know what the failure mode will be. badthink: the Fukushima backup generators must be placed on a platform to keep them out of the range of a once in a millenium tsunami goodthink: what happens when a typhoon comes and damages the generator on an exposed platform; an event which happens predictably and far more often than tsunamis. Answer: put the backup generators in the baseme…

A large seawall to be sure, but not a particularly tall one. If I recall correctly the seawall was remarkably short relative to maximum expected wave heights on a 100 year time frame.
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