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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

#71

Post by MBCook »

spenczar5 wrote: post #68
WalterBright wrote: post #66

Earlier quoted context omitted.

Airliners face constantly changing specifications. No two airliners are built the same.

Do you mean no two individual planes? Like two 767s made a month apart, do you mean they literally would have different requirements?

I think they meant a 737-400 is different from a 737-500 is different from a 787 and a AirBus 320 and a MD-80 and…

Every single model is somewhat bespoke. There’s common components but each ends up having its own special problems in a way I assume different car models in a common platform (or two small SUVs from competing manufacturers) just don’t.

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

#72

Post by WalterBright »

spenczar5 wrote: post #68
WalterBright wrote: post #66

Earlier quoted context omitted.

Airliners face constantly changing specifications. No two airliners are built the same.

Do you mean no two individual planes? Like two 767s made a month apart, do you mean they literally would have different requirements?

Yes. There are constant changes to the design to improve reliability, performance, and fix problems, and the airlines change their requirements constantly.

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

#73

Post by MBCook »

gumby wrote: post #34

30 years ago I was in an emergency landing due to engine failure situation (flight attendants take away your shoes, practice crash position, rearrange the passengers etc) and the thing that stuck out the most for me was that everybody did as they were told. No self righteous people; it was clear to everyone why there are flight attendants aboard and that they were key to your survival. The evacuation was orderly, tho…

You’re not supposed to take anything on the slides. No luggage. No shoes. Just you.

But it is ignored. Which is sad, people could really get hurt.

Your right though the fact as many people comply as they do is kind of incredible given how people act in other situations.

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

#74

Post by SkyPuncher »

peteradio wrote: post #55
V__ wrote: post #39

I'm wondering why the tolerances for the oil pipe were so small in the first place. Why not make the pipe one or two mm thicker?

Because its dead simple to machine a center and the designer did not factor in machinist/engineer/qa/facility incompetence.

I know very basic machining, but I know that part looks almost so simple I could manufacture it.

It’s very interesting that there were not wall thickness measurements. That would have solved this whole issue.

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

#75

Post by tempestn »

RetroTechie wrote: post #50
Cyberdog wrote: post #28

Earlier quoted context omitted.

I'm not familiar with the volcano incident you referred to, but a bit of searching seems to indicate it was British Airways Flight 009 in 1982, where a 747-200 had all four engines fail due to volcanic ash… then glided safely out of the ash cloud and was able to restart three of the engines and land safely at a major airport. From a complete loss of power to all engines to on the ground with zero deaths, zero injurie…

Sounds like the one! Engine after engine going out. Without (at first) any obvious cause. > From a complete loss of power to all engines to on the ground with zero deaths, zero injuries. That's exactly the kind of story I'm talking about that gives me such faith in flying! Understood (and agreed). But you missed my point: fate of that flight didn't result from safety engineering. It depended entirely upon the ash-lad…

> No amount of systems redundancy could have made it a safe flight.

But it did! One obvious example being the redundancy that allowed the plane to fly safely despite one of the engines not restarting.

The plane encountered an entirely unpredicted situation that caused damage, but thanks to its design was still able to land safely.

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

#76

Post by MBCook »

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 was going to mention him! I found his channel in the last year and have loved watching his coverage, especially from the point of view of a pilot.

If you like this article you’ll also likely like the show Air Disasters too (also known as Air Crash Investigations and Mayday, depending on where you are). It goes into a lot of detail based on crash reports without sensationalizing things too, though not quite as far as this article.

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

#77

Post by RajT88 »

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)

I was just thinking of this metaphor today.

Try drawing the software monstrosity you work on / with as an airplane. 100 wings sticking out all different directions, covered with instruments and fins, totally asymmetrical and 5 miles long. Propellers, jets, balloons, helicopter blades.

Yep, it flies.

When it crashes, just take off again.

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

#78

Post by SkyPuncher »

stevepeg wrote: post #45
XorNot wrote: post #21

The one thing which sticks out to me is the ECAM system including a baked corrective message of "open fuel transfer valves" due to the imbalance. That seems like an odd message to include in an emergency action system, which by definition is only active in unexpected situations. Is there really no system to confirm if a fuel leak is happening?

A320/330/340/350 driver here (can't get away from Airbus apparently). Nope, there is no system to confirm a leak apart from a camera around the tail if you're lucky enough to have one, my previous airline had a flight where an engine leak was detected this way. Think about it, how would you design such a system? So this falls on the crew. The procedure to determine if you have a leak is pretty much the same across ty…

You could absolutely design a system that could detect a leak. I’m guessing that it’s just not common enough, or at least catastrophically common enough, to warrant.

At its simplest you measure estimated volume delivered to the engines against estimated volume remaining in the tank. Both are things that should be digitally measurable.

The problem seems to be that the only case it really matters is in a catastrophic accident where such measurements are going to be broken anyways.

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

#79

Post by MBCook »

metadat wrote: post #10

An amazing recovery, there's even an Air Crash Investigations episode about it: https://imdb.com/title/tt3234896/

Love that show. Makes me wish we dealt with software even a tiny bit like that. Checklists alone for troubleshooting common customer problems would save so much hassle.

But so many companies (including mine) still work on more of the “heroic” model where it’s up to individuals to just learn the hard way through helping lots of customers and noticing patterns.

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

#80

Post by MBCook »

WalterBright wrote: post #69
V__ wrote: post #39

I'm wondering why the tolerances for the oil pipe were so small in the first place. Why not make the pipe one or two mm thicker?

Because there are a zillion important parts on the airplane, if you make each one heavier than it needs to be, the airplane will be nailed to the tarmac.

That makes sense. Here’s the question I left the article with:

Why not counterbore the pipe before installation, so it’s a trivial process?

Would it then not survive welding perhaps?

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