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Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

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Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#51

Post by kergonath »

mmooss wrote: post #15

Does anyone know the author's background? All I see is 'analyzer of plane crashes'.

I am not sure about her formal credentials, but she’s doing a very thorough job. I could not find a flaw in her explanations involving my field (materials science broadly, and failure mechanics in particular), which is more than I can say of the vast majority of people writing on STEM subjects. I don’t think she has any formal training in the field, but she seems to be talking to the right experts and extracting the right information.

I believe she used to be a pilot.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#52

Post by tgsovlerkhgsel »

userbinator wrote: post #28

In all tests, the fire, propelled by the oxygen leak, produced a terrifying “blowtorch” effect, and the flames were literally white-hot. Sufficient concentrations of oxygen can cause even steel to burn: https://en.wikipedia.org/wiki/Thermal_lance There must be a reason they use pure oxygen, as regular compressed air, also breathable, would not have the same intense reactivity.

If you put a human in an environment with 20% of sea level pressure, and feed them 20% sea level pressure air, they will suffocate.

If you were to somehow feed them 100% sea level pressure air through a perfectly sealed mask, they will be unable to exhale and/or get some kind of fatal side effects (burst lungs or air bubbles making it into the blood stream). So you have to feed the breathing gas at the surrounding pressure.

If, however, you give them 100% oxygen at 20% sea level pressure, they will be able to happily breathe it as if it was regular air with 20% oxygen near sea level, at least until you introduce an ignition source. What matters physiologically is the partial pressure (pressure multiplied by fraction).

(Likewise, if you give someone 100% oxygen at sea level pressure for a short time, they'll be fine. Do the same at more than twice sea level pressure, e.g. while diving, and the oxygen becomes fatally toxic.)

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#53

Post by tgsovlerkhgsel »

amelius wrote: post #31

With all the high speed trains in Europe, I'm wondering why we don't see more security around them. It seems a much easier target than airplanes.

You can (usually) stop a train within less than a minute and then trivially evacuate it.

They're also less dense than most other public transport, including planes.

And it's impossible to add security to local transit, because standing for 15 minutes at a security checkpoint for a 15 minute bus ride will make everyone get a car and/or unelect the idiot who implemented that rule.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#54

Post by kergonath »

eddythompson80 wrote: post #44
fragmede wrote: post #43

Earlier quoted context omitted.

But you can do all of these: https://en.m.wikipedia.org/wiki/List_of_terrorist_incidents_...

In all those examples trains are no different than movie theaters, malls, markets, sport and music events, etc. i.e: just places where large groups of people gather.

And all these places are easier targets with more people.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#55

Post by ngneer »

Dalewyn wrote: post #50
ngneer wrote: post #49

Earlier quoted context omitted.

Very interesting. Thank you for making the distinction explicit and for helping me to understand the other mindset. You are totally right, in that my mindset is closer to a forensics mindset in such instances, trying to get as close as possible to the "truth", so as to avoid future similar defects and improve system reliability. I do agree that some people prefer to manufacture truth. Any advice on how to get along w…

Much like how you can't convince a businessman to understand something when his salary depends on him not understanding it, it's next to impossible to "find out" a mystery if the powers-that-be do not want that and/or want a more desirable-for-them conclusion.

I was afraid you were going to say that ;). Thanks for the sage advice. I think that "safety inspector" would not be a good career choice for people like myself, then. Methinks Boeing and OceanGate had been in the news recently with similar safety attitudes. Oh, well. Live and learn.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#56

Post by WeylandYutani »

amelius wrote: post #31

With all the high speed trains in Europe, I'm wondering why we don't see more security around them. It seems a much easier target than airplanes.

The easiest target is plowing into a crowd with a car. Learning how to drive train is beyond the unhinged morons.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#57

Post by kergonath »

cyberax wrote: post #42
bitwalker wrote: post #36

Earlier quoted context omitted.

> It really sucks the heat out of it. One of the problems with halon, and the write-up mentions this, is that it is super effective at starving the fire of oxygen, but has zero effect on the heat of the fuel that was burning. So the fire goes out, but if oxygen is reintroduced before the fuel has a chance to cool sufficiently, it reignites - and now not only are you back where you started, but you have all the toxic…

> One of the problems with halon, and the write-up mentions this, is that it is super effective at starving the fire of oxygen That's not actually quite how it works. But yes, the end result is the same. I'll copy-paste my comment from the Medium: That's NOT how halon works! It's a common misconception, but it's incorrect. In fact, halon doesn't react with pretty much anything, it's very chemically stable. You can mi…

> That's not actually quite how it works.

What you wrote is not contradicting the parent, who just said that it was “super effective at starving the fire of oxygen”. You just described the mechanism. You also contradict yourself by first saying that halon is inert, and then that it neutralises oxide ions by swapping halogens, which is the opposite of non-reactive. The effect of that is that it immobilises reactive oxygen before it oxidises the fuel. And it indeed does nothing to decrease the temperature, which does mean that the fire restarts as soon as oxygen is re-introduced. I know you’re not wrong, but the delivery could be improved.

Anyway, you can elaborate and provide information without disagreeing with the comment you’re replying to. It’s fine, and often informative.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#58

Post by brnt »

ngneer wrote: post #45
eddythompson80 wrote: post #22

Earlier quoted context omitted.

> My takeaway is that the French investigators are pros and the Egyptians are hacks Describing them as "hacks" is weird. In most dictatorships, the concern is usually "What does the country's leadership want the official story to be" rather than "What actually happened". Take this quote from the article for example > "In my opinion, the problem with the report is that it appears to treat the findings of the Triple Co…

You make a valid point. I stand corrected. "Hacks" is not an accurate term, and fails to account for the full circumstance. I was merely appalled at how willing EAAID were to jump to conclusions and twist facts towards a convenient narrative. France is a democracy, and that makes for an unfair comparison between the two agencies. I am sure that even the most intellectually honest individual will choose their own safe…

Such are the mechanics of fascist dictatorships. Individuals are in no way empowered to think or act in ways not supporting the Great Leader. You being unsafe is the method of control.

Take care, America.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#59

Post by wkat4242 »

kergonath wrote: post #57
cyberax wrote: post #42

Earlier quoted context omitted.

> One of the problems with halon, and the write-up mentions this, is that it is super effective at starving the fire of oxygen That's not actually quite how it works. But yes, the end result is the same. I'll copy-paste my comment from the Medium: That's NOT how halon works! It's a common misconception, but it's incorrect. In fact, halon doesn't react with pretty much anything, it's very chemically stable. You can mi…

> That's not actually quite how it works. What you wrote is not contradicting the parent, who just said that it was “super effective at starving the fire of oxygen”. You just described the mechanism. You also contradict yourself by first saying that halon is inert, and then that it neutralises oxide ions by swapping halogens, which is the opposite of non-reactive. The effect of that is that it immobilises reactive ox…

As far as I understood it reduces temperature also because it boils so easily (very low boiling point). That pulls energy from the fuel. As well as capturing oxygen.

This is why it was used as a refrigerant also.

Also if the fuel is below the auto ignition temperature but above flashpoint it would need another spark to re-ignite.

Re: Masks, Smoke, and Mirrors: The story of EgyptAir flight 804

#60

Post by cyberax »

kergonath wrote: post #57
cyberax wrote: post #42

Earlier quoted context omitted.

> One of the problems with halon, and the write-up mentions this, is that it is super effective at starving the fire of oxygen That's not actually quite how it works. But yes, the end result is the same. I'll copy-paste my comment from the Medium: That's NOT how halon works! It's a common misconception, but it's incorrect. In fact, halon doesn't react with pretty much anything, it's very chemically stable. You can mi…

> That's not actually quite how it works. What you wrote is not contradicting the parent, who just said that it was “super effective at starving the fire of oxygen”. You just described the mechanism. You also contradict yourself by first saying that halon is inert, and then that it neutralises oxide ions by swapping halogens, which is the opposite of non-reactive. The effect of that is that it immobilises reactive ox…

Typically, "starving of oxygen" means that there's not enough oxygen around anymore. That's how CO2 extinguishers work, for example. They literally remove enough of the oxygen to make the combustion stop.

Halon does NOT remove the oxygen, there's always plenty of it available. Instead, it stops the chain reaction.

> You also contradict yourself by first saying that halon is inert, and then that it neutralises oxide ions by swapping halogens, which is the opposite of non-reactive.

As I said, you can mix halon and oxygen, and they won't react (even if you try to ignite them). Halon is very unreactive, but it's obviously not _totally_ inert like helium.

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