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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

#241

Post by WalterBright »

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.

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 strong enough to never break

goodthink - what happens when there's enough force to bust the pipe off? Answer: the pipe flow cannot be shut off. Solution: put a fuse (a weak spot) above the valve, so when the pipe busts off, it breaks above the valve, and the valve can be turned to shut off the flow. (The valve was located on the sea floor.)

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

#242

Post by WalterBright »

uselpa wrote: post #126
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.

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.

There are a fair amount of backups in your car. For example, the braking system is dual. There's also engine braking and the parking brake that can be used. All the "energy absorbing" features are a backup for when you crash.

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

#243

Post by ardel95 »

The story of what happened in the cockpit during the failure is just as interesting! The captain made a number of right decisions in a very challenging situation that allowed the plane to safely land.

Mentour Pilot did a video on that: https://youtu.be/JSMe1wAdMdg?si=YSgbqFpR_EBe-FvX

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

#244

Post by WalterBright »

laydn wrote: post #145
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.

What's fascinating about airplane design for me is not the huge technical complexity, but rather, the way it is designed such that a lot of its subsystems are serviceable by technicians so quickly and reliably, not just in a fully controlled environment like a maintenance hangar, but right on the tarmac, waiting for takeoff.

Designing the airplane to minimize required maintenance and to make maintenance and inspections easier and faster is a huge issue for the engineering department. Also make it very difficult for the mechanics to do things wrongly.

As it was pointed out to me, airplanes sitting on the ground are a black hole sucking up money. Airplanes in the air carrying payload (note the "pay" in payload) are making money. Boeing understands this very well, and is very focused on getting that airplane in the air making money as much as possible.

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

#245

Post by WalterBright »

paulmd wrote: post #229
pbhjpbhj wrote: post #188

Earlier quoted context omitted.

How are aeroplanes designed differently at Boeing vs Airbus? What's the secret sauce?

At this point the secret sauce is that the EAA isn’t tolerating the same degree of certification fucking and laxity from airbus, and that they generally seem to have their act together. Like what’s the secret sauce of nvidia vs radeon or AMD vs intel? Reliable execution, seemingly - and this is an environment where failures are supposed to be contained to very specific rates at given levels of severity. The FAA has g…

It's actually safer for new airplane types to have flying characteristics like the previous types. There have been many accidents where a situation happened and the pilot did the right thing for the previous airplane he flew, but was the wrong thing for the one he was currently flying.

Most of what was written about the MAX crashes in the mass media is utter garbage and misinformation. No surprise there, as journalists have zero expertise in how airplanes work.

Both crashes could have been easily averted if the crews had followed well-known procedures. There was also nothing wrong with the aerodynamics of the MAX, nor the concept of the MCAS system. The flaw was in the way the MCAS system was implemented, and the way the pilots responded to it.

For example, rarely mentioned is the third MAX incident, where the airplane continued normally to their destination. The crew simply turned off the stab trim system.

BTW, I had a nice conversation with a 737 pilot a few months ago. He told me what I had already concluded - the crashed crews did not follow the procedures. I've also had unsolicited emails from pilots who told me what I'd written about it was true.

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

#246

Post by otherme123 »

ogurechny wrote: post #165

The article is complex and well written, but I am a bit perplexed by the victorious tone and never-ending praise of safety. It resembles a sales pitch a bit too much, even though no one is selling anything. Maybe it's unintentional, and being around salesmen just does that to people. If you are like me, you've probably said “hmm…” to yourself multiple times when certain things were mentioned, because those were thing…

I've read dozens of Admiral Cloudberg articles, and when you do so you notice a pattern: in old aviation crashes, a single error or a single part failure usually took down a plane with tens of dead bodies. Also the story of how and why the sterile flight deck started in response to some crashes where the pilots were distracted talking. In modern aviation accidents, it seems very unlikely. Even with an engine exploding, the pieces ripping half the cables, a wing, the fuel reservoir, hydraulics, and the airplane is still almost perfectly flyable and landable. Do the same to any car, were nothing is redundant, and lets see how well it performs.

The beauty of it is that everyone in aviation seems eager to learn and build on errors. This event prompted new actions that makes future flying even safer, despite having no victims.

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

#247

Post by mango7283 »

pxmpxm wrote: post #235
mango7283 wrote: post #194

Earlier quoted context omitted.

Well the whole point of articles like this is that they are more "literary" than the investigation reports and therefore more entertaining and engaging to read. There's a time and place for reading dry technical investigation reports and this is not one of them. Also, none of the adjectives you highlighted are beyond human comprehension or usage or even rare so it's certainly not an example of what parent was trying…

Taking a sentence and doubling the world count with folksy-sounding adjectives does not actually make the prose more "literary". It's just bad copy...

It's a matter of taste. Clearly many of us here were entertained by the style of the blog vis a vis the wiki version or other sources of the same information.

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

#248

Post by stevepeg »

SkyPuncher wrote: post #193
stevepeg wrote: post #105

Earlier quoted context omitted.

It’s a good idea, some aircraft have quite complex fuel systems though so it would have to account for fuel moving between tanks. E.g. the A330 has an inner tank in each wing (which itself can be split into two compartments if damaged), an outer tank in each wing and fuel in the horizontal stabiliser which is used for CG control in the cruise. All of that plumbing can leak too. You’d be adding significant weight and…

All of that only adds complexity in the calculation, not the measurement. The engines have predictable fuel consumption patterns. Even if fuel move across a bunch of tanks, you can still calculate total onboard fuels and detect a leak.

That’s what it already does though. We get a total fuel figure in the flight deck (FOB) and a figure for how much the engines have used (FU - measures flow in the pylons). Add the two together and if the resulting number isn’t what the flight started with then there’s a leak.

The challenge is knowing where the leak is.

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

#249

Post by andrewaylett »

sgarland wrote: post #231
bambax wrote: post #141

Earlier quoted context omitted.

The Checklist Manifesto (2009) is a great short book that shows how using simple checklists would help immensely in many different industries, esp. in medical (the author is a surgeon). Checklists of course are not the same as detailed post-mortems but they belong to the same way of thinking. And they would cost pretty much nothing to implement. Also CRM: it's very important to have a culture where underlings feel th…

Yes, but they do have one critical failure mode: that the checklist failed to account for something (or that an expected reaction to a step being performed didn’t occur). I was a submarine nuclear reactor operator, and one of my Commanding Officers once ordered that we stop using checklists during routine operations for precisely this reason. Instead, we had to fully read and parse the source documentation for every…

If the alternative to the check list is reading the full documentation, that's one thing. But in my experience -- as a Software Engineer, and random dude on the Internet -- the alternative is usually no check list or documentation.

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

#250

Post by WalterBright »

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.

An example of zipper failure in the Airbus incident is when a wire bundle gets cut, all the functions of all the wires in that bundle are lost. Having two or more smaller bundles physically separated would greatly reduce that risk. Certainly, having the primary and the backup system in the same bundle is a bad idea.

On the 757, one set of control cables runs under the floor. The backup set runs in the ceiling.

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