[HN Gopher] Masks, Smoke, and Mirrors: The story of EgyptAir fli...
___________________________________________________________________
Masks, Smoke, and Mirrors: The story of EgyptAir flight 804
Author : gdmt
Score : 228 points
Date : 2024-12-24 19:39 UTC (1 days ago)
(HTM) web link (admiralcloudberg.medium.com)
(TXT) w3m dump (admiralcloudberg.medium.com)
| soapboxrocket wrote:
| Reminds me a bit of the UPS Flight 6 that crashed in 2010. Wasn't
| the cause of the fire, but the fire heated up the co-pilots
| oxygen system to the point he couldn't wear it and eventually
| succumbed to smoke hypoxia. Due to smoke in the cabin the pilot
| couldn't see his flight deck readouts or out the window and
| eventually crashed into the ground.
| veeti wrote:
| From the same author:
| https://admiralcloudberg.medium.com/alone-in-the-inferno-the...
| ddalex wrote:
| One would have to wonder why an emergency smoke extractor fan
| isn't default equipment - when pilots oxy is deployed a panel
| should blow outward and a high flow fan start.
| dmckeon wrote:
| Tragedy from a Swiss cheese failure - several small
| holes/failures all line up. The issue of halon extinguishers
| versus oxygen-powered combustion producing many toxins while
| failing to extinguish is interesting - good that:
|
| > Halon fire extinguishers are scheduled to be phased out of most
| commercial aircraft by the end of 2025.
| wkat4242 wrote:
| That's more because of the ozone layer.
|
| While it's not good to use halon in a semi contained space like
| an airplane, it is incredibly effective at killing fire. It
| really sucks the heat out of it. Thus in most cases the fire is
| killed quickly and not much toxins are produced. This is
| important too because fire itself produces a lot of lethal
| toxins too, most people in a fire don't burn to death but get
| poisoned by the smoke.
|
| So it's a big loss imo. I understand why because it's one of
| the most potent ozone layer killers. But still.. you're not
| using the stuff unless you have no other choice. If you're not
| using it it doesn't end up in the environment.
|
| In this case it didn't work because the cargo bay in question
| was not fitted with extinguishers if I remember correctly.
| bitwalker wrote:
| > 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 byproducts that burning halon
| produces, which will kill you in a hurry if you breathe them
| in.
| cyberax wrote:
| > 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
| mix halon with pure oxygen and it'll just sit there, doing
| nothing.
|
| This stability is exactly why it works so well. You need
| only a few _percent_ of halon by volume to stop the fires,
| not even close to consuming even a fraction of the 21% of
| oxygen.
|
| Normal oxygen consists of two atoms bonded together (thus
| "O2"). And fire is spread by oxygen radicals, lone oxygen
| atoms that have an unpaired electron, eager to make bonds.
| In a fire, an oxygen radical reacts with a molecule of
| fuel, and this reaction produces enough energy to create at
| least one more oxygen radical, sustaining the chain
| reaction.
|
| But halon has these chlorine and bromine atoms, they are
| bound tightly to carbon, but not as tightly as oxygen would
| be. So oxygen radicals have enough energy to displace them
| and bind to the central carbon atom. But the resulting
| energy release is not enough to create _more_ radicals, so
| the chain reaction is stopped.
|
| Moreover, the chlorine radical can then snap back onto
| another carbon atom (from the fuel source), releasing a bit
| of energy, but not enough to create a new oxygen radical.
| And the cycle can repeat again.
| kergonath wrote:
| > 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.
| wkat4242 wrote:
| 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.
| cyberax wrote:
| 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.
| userbinator wrote:
| _As I said, you can mix halon and oxygen, and they won 't
| react (even if you try to ignite them)._
|
| That makes me wonder if any of the original designers of
| the oxygen system considered whether a halon-oxygen mix
| would've been better than pure oxygen.
| cyberax wrote:
| Not really. Adding oxygen for sure won't help. Also halon
| is stored in extinguishers as a pressurized liquid, not
| gas.
| cyberax wrote:
| This really is a non-issue. If you're at the point where toxins
| from halon pyrolysis are a problem, then you're likely already
| dead from other factors (heat, smoke, etc.).
|
| Halon can works even at concentrations of just 2-5% by volume.
| This is entirely safe to breathe for humans. There's a video of
| a person discharging a halon extinguisher in a room, and then
| proceeding to try to light a cigarette. The matches go out
| immediately after striking the matchbox and the lighter can't
| even ignite.
|
| CO2 extinguishers are really worse, they need to displace most
| of the oxygen to be effective. Unfortunately, humans also need
| this oxygen.
|
| In addition, CO2 stream can cool the burning material, but it
| can also spread it (so be careful if you use it on burning
| liquids).
| jabl wrote:
| Engine rooms in ships typically have CO2 systems. There's
| been several fatalities when crew have reentered the space
| before the CO2 has been ventilated away. Made worse by CO2
| being heavier than air so it can remain in some crawlspace
| under the engine frame or such.
| buildsjets wrote:
| In testing aircraft installations, the FAA requires you to
| demonstrate 6% concentration of Halon 1301 at 12 FAA chosen
| locations in a compartment for 0.5 seconds, simultaneously,
| when the test is run at sea level and standard temperature.
| This is to allow for the fact that the halon bottles may be
| cold soaked down to -60F and that the system needs to be
| effective at density altitudes down to -1000 feet.
| wk_end wrote:
| In commercial aviation the vast majority of tragedies _are_
| Swiss cheese failures, at this point. The system has worked
| very hard to optimize out the possibility of any one individual
| failure leading to catastrophe. But the explosion of potential
| combinations - along with the extremely low odds of them ever
| occurring - makes preparing for one of them much less feasible.
| FridayoLeary wrote:
| I'm surprised that a catastrophic runaway oxygen leak is
| possible on an aircraft in todays day and age. Aircraft
| design is dominated by strict safety regimes that take into
| account even far fetched scenarios. Putting one valve in the
| rubber hose sounds sub optimal. Gas station pumps, for
| example have a valve that closes if the hose gets torn away.
| (which does happen when people forget about the pump and
| drive off). From the article it sounds like a button closes
| the oxygen tank but a pilot sitting next to a flamethrower
| might not remember to press it. One obvious solution is that
| the oxygen tank should be activated only in an emergency
| instead of being on by default during the flight but i assume
| the current procedure exists for a reason.
| masklinn wrote:
| The rarity of such events (as outlined by TFA) is probably
| a major reason, even more so as they seem to _generally_ be
| caused more by maintenance and from places with less than
| stellar incident reporting.
|
| While there is some amount of proactivity in aircraft
| safety I'm not sure there are people with enough free time
| that they can make up failure modes or trawl through every
| minor incident report until (again as in the case of TFA)
| prompted by an actual failure, unless one of the minor
| incidents is itself proactively raised as a major risk
| avoided by blind luck.
| wat10000 wrote:
| The article says that a risk analysis was done for the
| system and the risk was found to be "extremely improbable,"
| meaning between 1 in 100 million to 1 in a billion flight
| hours.
|
| This flight may have been extremely unlucky, or the risk
| analysis may have been wrong. This is why the behavior of
| the Egyptian authorities is so frustrating; the purpose of
| the accident investigation is to see if there are problems
| that should be addressed.
| CamperBob2 wrote:
| Also, even if the risk analysis was right, it didn't
| justify an "extremely improbable" conclusion. If the
| global airline industry operates a total of about 50
| million flights per year, and the average duration is
| about 2 hours, then we stand a good chance of seeing an
| accident like this every few years.
| wat10000 wrote:
| Reading up a little on the regulations, the FAA defines
| "extremely improbable" as less than one in a billion per
| hour, with the goal that a given type of airplane should
| be unlikely to ever experience a catastrophic failure
| during its service life.
|
| Of course, there's more than one type of airplane in the
| world, so you do have to wonder if that standard is
| adequate. I didn't see how they quantify "unlikely," but
| if it's, say, 1 in 10 then the wide range of aircraft
| types means many of them will experience a catastrophic
| failure.
|
| I'd expect this stuff to be gradually tightened. The
| current standard would have been ridiculous and
| unobtainable some decades ago. As technology and
| experience advances, there should be room to improve it
| further.
| buildsjets wrote:
| No, they are not. Source: me. Also here's the applicable EU
| regulation. https://eur-lex.europa.eu/legal-
| content/EN/TXT/?uri=CELEX%3A... Only handheld portable
| extinguishers are required to be phased out in 2025, and only
| in locations that are regulated by EASA. The FAA does not give
| a rip, and neither to the many regulatory bodies around he
| world who defer tho the FAA. I don't know what the CAAC is
| doing. As far as the FAA concerned, compliance with the
| Montreal Treaty is the Department of State's problem. Btw,
| since there is only one company that has certified a non-halon
| (2-BTP) handheld, they have jacked the retail/list price up to
| $2630 compared to an equivalent sized Halon 1211 handheld for
| $475.
|
| Did you know that in the wrong circumstance a 2-BTP
| extinguisher will feed a fire rather than extinguish it? It's a
| phenomenon called subinerting. One manufacturer blew up an FAA
| lab pretty badly while testing 2-BTP. Here's a report on the
| earth-shattering kaboom. I only got to see he wreckage a few
| weeks later. https://www.nist.gov/publications/chemical-
| kinetic-mechanism...
|
| Permanently installed Halon firex systems in commercial
| aircraft will not be phased out until 2040. I have been
| working, as a part of larger team, to certify a non-halon based
| firex in cargo and engine compartments for many many years now.
| It's been slow going. All commercial aircraft from all
| manufacturers still use Halon for their permanently installed
| firex and will continue to do so for the near future. We have
| put non-halon systems into some military aircraft that go thru
| a commercial certification, for example the KC46 tanker, but
| there are some good reasons it would not be the best choice for
| an actual commercial aircraft. https://www.af.mil/News/Article-
| Display/Article/740629/kc-46...
|
| If anyone actually gave a rip about ozone depletion, they would
| ground the F-16 fighter. The F-16 inerts it's fuel tank ullage
| space with Halon. Every F-16 flight is a direct injection of
| pure Halon straight into the stratosphere. Mainline that stuff,
| feels so good. https://arc.aiaa.org/doi/abs/10.2514/6.1981-1638
| inglor_cz wrote:
| On a somewhat related note, Egyptian science tends to suffer from
| a massive scientific misconduct (fraud) problem - see for example
| this paper by Egyptian authors, which covers the medical field:
|
| https://www.medrxiv.org/content/10.1101/2023.02.20.23286195v...
|
| Maybe the attitude towards "truth vs. face" is similar in
| Egyptian governmental institutions.
|
| Egypt in general is a low-trust society, scoring lower than India
| or Russia, though not much lower than usual in Africa.
|
| https://www.reddit.com/r/MapPorn/comments/iab8r7/social_trus...
|
| This indicates that lived experience of the Egyptians themselves,
| when it comes to trusting others, is somewhat bad.
| aprilthird2021 wrote:
| Of course it is, it's a brutal military dictatorship where the
| last (and only) democratically elected leader was overthrown by
| the army and died in prison.
|
| Those kinds of systems, where people are convinced their
| opinions and convictions don't matter, lead to problems like
| this
| dash2 wrote:
| This might get the causality backward. Most high trust
| societies were high trust before, not after, they became
| democracies.
| aprilthird2021 wrote:
| I think most democracies were founded as such and so the
| society and democracy were born at the same time
| inglor_cz wrote:
| Nope, democracies are usually much younger than the
| underlying societies.
|
| For example, the vast majority of Europe is now
| democratic. 200 years ago, most of Europe was autocratic
| and even exceptions like the UK were at most very
| incomplete democracies with limited suffrage.
|
| But the constituent nations and ethnicities are very much
| the same, even though political boundaries have shifted;
| an English, Polish or Spanish person can read 200 year
| old texts without much effort. There wasn't any seismic
| shift comparable to the collapse of the Roman world and
| the subsequent rearrangement of nations and ethnicities
| across the continent. Krakow is still Polish, Budapest is
| still Hungarian and Milan is still Italian.
|
| Only in a few places like Breslau/Wroclaw there was a
| meaningful population shift.
| aprilthird2021 wrote:
| But most democratic countries in the world are not in
| Europe. Most of them were born as democracies: India,
| Tanzania, Kenya, Nigeria, USA, etc.
| eadmund wrote:
| > Maybe the attitude towards "truth vs. face" is similar in
| Egyptian governmental institutions.
|
| My initial instinct when reading the prologue was to think
| about that, and be proud that we're not like that. But then I
| reflected a bit more, and wondered. When folks say something we
| dislike, do we consider that it may be true, or do we shut down
| the conversation?
|
| I'm reminded of the response to any number of public
| controversies in my lifetime, when unpopular arguments did not
| result in compelling counter-arguments but instead in shout-
| downs.
| inglor_cz wrote:
| This is a good observation, but as usual, everything comes in
| degrees of severity.
|
| To fabricate an implausible report about a plane crash which
| took more than 60 lives is a very deep institutional problem,
| let us hope that this won't become the planetary norm.
| aprilthird2021 wrote:
| It's actually a shallow institutional problem. If the
| dictator wants the report to say one thing, it must, the
| end.
| ngneer wrote:
| A rather well-written piece. My takeaway is that the French
| investigators are pros and the Egyptians are hacks. And that
| safety culture matters. One must not bend the facts to draw a
| desired conclusion. One must review the data without bias, or
| else recuse oneself.
| eddythompson80 wrote:
| > 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 Committee -- the
| group appointed by the public prosecutor's office -- as the
| unquestioned truth, and fails to push back on any of its
| assertions, even the ones that they disagreed with. Instead,
| because the Triple Committee concluded that a bomb in the
| galley was the cause of the crash, the EAAID bent itself into a
| pretzel trying to make the evidence fit that theory.
| Unfortunately, we don't know why the Triple Committee and the
| EAAID chose to die on this hill"
|
| EgyptAir is a government owned enterprise. It's managed by the
| "Ministry of Civil Aviation" who's head is always some general
| or commander from the Air Force. If the EAAID investigators
| were allowed to say that there was a "faulty equipment" then a
| lot of questions would have had to be answered. A lot of
| questions that have the possibility of embarrassing people all
| the way up the chain (especially that as mentioned, that
| particular oxygen mask was reported faulty from another
| aircraft and removed for maintenance before, and the crew
| frequently reported that the pilot oxygen supply always
| decreases on every flight).
|
| Saying "it was terrorists" is something that no one has to feel
| embarrassed about. In fact in 2016 the Egyptian government were
| in the midst of a lot of arrests and suspension of most
| freedoms to "curb terrorist activities". And such thing plays
| well into that narrative.
|
| Are you an EAAID investigator who wants to say "it was a faulty
| oxygen mask"? Ok. How do you fancy you, your brother, cousin,
| and neighbor spending the next 15-30 years in jail pending
| investigation on conspiracy against the country?
| ngneer wrote:
| 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 safety if faced with the reality of imprisonment.
| brnt wrote:
| 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.
| llamaimperative wrote:
| Yeah people dictator-sympathizers seem to think the
| problem with strongman asshole leaders is that they're
| meanie heads (something Real Patriots can look past!).
| But no, it's that they actually yield failure in a
| society's most basic functions and at every level.
| lazide wrote:
| It often takes a degree of pain unimaginable to people to
| realize the true consequences of going down this road.
| Sometimes, that pain is so extreme people can never do
| it.
|
| See post WW2 Germany, and all the folks who got caught
| with nazi memorabilia in their attics for decades
| afterwards.
| mlinhares wrote:
| Please don't put the blame on dictatorships alone,
| democratic countries do the same all the time. There's
| multiple cities in the US where the city officials hid
| the fact their water was contaminated.
| nico wrote:
| > France is a democracy
|
| And even there, sometimes people will get treated like
| terrorists for saying the wrong political thing
|
| Like it's been happening for the last year. Including some
| protests getting outright made illegal
|
| And as you say, even people that care a lot about the
| truth, will choose something else to protect themselves or
| their loved ones
| Ozzie_osman wrote:
| > In most dictatorships, the concern is usually "What does
| the country's leadership want the official story to be"
| rather than "What actually happened".
|
| This also occasionally happens in non-dictatorships, unless
| you considered George W a dictator when he was deciding to
| invade Iraq.
| Moru wrote:
| Whataboutism isn't really the answer here. When the
| population knows this is the way it works and bends
| themselves like a pretsel to make their government not kill
| them, it's not good. You can't compare that to a western
| country, not even the US is that bad.
| sofixa wrote:
| It's not the first time Egyptian investigators disregarded
| reality to keep face:
|
| https://admiralcloudberg.medium.com/the-crash-of-egyptair-fl...
| Dalewyn wrote:
| >One must not bend the facts to draw a desired conclusion. One
| must review the data without bias, or else recuse oneself.
|
| There are essentially two ways to solve a mystery:
|
| A) Consider the evidence and draw a conclusion from them.
|
| B) Consider the conclusion and draw the evidences for it.
|
| Neither is _the_ correct methodology, especially when politics,
| power dynamics, and social justice are involved.
| ngneer wrote:
| With all due respect, (B) is logically unsound in my mind.
| You may have meant considering the hypotheses, and then using
| available data and only available data to rule in or rule out
| certain scenarios. In my mind, based on decades of studying
| engineering defects and failures, starting with a conclusion
| is not a way to solve a mystery at all. Rather, it is only a
| way to convince oneself of a falsehood. To give an example
| that is familiar to the HN audience, how many times have you
| had to debug a bug or problem in a complex system that you
| initially thought was caused by one thing only to discover it
| was caused by something completely different?
| Dalewyn wrote:
| >With all due respect, (B) is logically unsound in my mind.
|
| That's because you're concerned about _finding out_ what
| happened. Not everyone thinks like that, namely some (many)
| are concerned about _creating_ what happened.
| ngneer wrote:
| 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 with
| these?
| Dalewyn wrote:
| 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.
| ngneer wrote:
| 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.
| lazide wrote:
| Notably, the type of people who do B are extremely
| dangerous around anything involving engineering, science,
| etc - anything where reality actually matters.
|
| Because type A people are what are required to _actually_
| fix problems, or learn more things.
|
| Type B people exist when those are 'not desirable'. Which
| should indeed scare you, if you care about actual reality
| (or actual reality matters) in that domain.
| Moru wrote:
| Especially when type A people are working in an
| environment where the leadership with the guns is type B
| people. Then type A will proactively switch to type B
| reasoning to stay alive.
| synecdoche wrote:
| Could someone explain when A) it's not the correct
| methodology, unless B) is preferable?
|
| B) appears preferable only under duress and then only to the
| benefit of saving one's own skin temporarily, however long
| that may be.
| Hilift wrote:
| Egypt doesn't have an equivalent to the NTSB. There simply
| isn't enough depth. They established their own agency in 2002,
| but it is basically a placeholder.
| Ozzie_osman wrote:
| It's easy to say this sitting in the west, especially since
| Egypt is run by an authoritarian government. I'll point out
| though that even sans-authoritarianism, there are plenty of
| examples of Western "investigators" arriving at politicized and
| often false conclusions with far worse consequences. The
| history of the CIA/FBI is chock-full of examples. And you don't
| even have to go that far back or dig that deep... The whole
| Iraq WMD debacle.
|
| Anyway, not saying the Egyptian investigators were right in
| this case (it seems clear that they weren't). Or defending
| authoritarian governments. Just providing an alternative view
| point, as someone who lived half his life in Egypt and half in
| the US.
| mmooss wrote:
| Does anyone know the author's background? All I see is 'analyzer
| of plane crashes'.
| buildbot wrote:
| She is I believe a pilot, and has been doing this for years and
| years on (originally?) reddit, in great depth and detail. She
| also has a really fun podcast with two other people called
| controlled pod into terrain.
| macintux wrote:
| A little information:
| https://www.patreon.com/admiral_cloudberg/about
| sofixa wrote:
| She's one of the best, extremely thorough, and works as a
| researcher for another very good air crash investigator,
| Mentour Pilot (YouTube channel).
| kergonath wrote:
| 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.
| efitz wrote:
| Do you see something in the article that should require
| credentialing to state?
| blueflow wrote:
| See https://avherald.com/h?article=4987fb09/0018 for a technical
| view.
| userbinator wrote:
| _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.
| dreamcompiler wrote:
| > Sufficient concentrations of oxygen can cause even steel to
| burn
|
| Not just thermal lances; oxy-acetylene cutting torches work by
| burning through steel, and you can buy one for not much money
| at almost any hardware store.
| wezdog1 wrote:
| It's used due to the low partial pressure of oxygen at high
| altitudes
| tgsovlerkhgsel wrote:
| 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.)
| wat10000 wrote:
| Incidentally, it is possible to provide the breathing gas at
| somewhat over the ambient pressure. This can allow survival
| without cabin pressurization at altitudes above the point
| where even 100% oxygen wouldn't be sufficient. But the
| pressures that can be used are well below what you'd need for
| normal air to be sufficient at a typical airliner cruising
| altitude.
| masklinn wrote:
| > There must be a reason they use pure oxygen, as regular
| compressed air, also breathable, would not have the same
| intense reactivity.
|
| Pure oxygen at 1/5th standard pressure has the same effect as
| air at standard pressure, and assuming nitrogen and oxygen
| compress similarly you can either fit 5 times more in the same
| canister, or you can have a canister 1/5th the size and weight.
| amelius wrote:
| 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.
| shepherdjerred wrote:
| I'm guessing it's because you can't fly a train into a building
| fragmede wrote:
| given how long and heavy trains are, and how fast they can
| go, and the fact that rails aren't straight, sure you can.
|
| https://spectrumlocalnews.com/tx/south-texas-el-
| paso/news/20... a train crashed into the chamber of commerce
| building in Pecos Tx 5 days ago.
| shepherdjerred wrote:
| ...yes, but you can't do this with a train
| https://en.wikipedia.org/wiki/September_11_attacks
| fragmede wrote:
| But you can do all of these:
|
| https://en.m.wikipedia.org/wiki/List_of_terrorist_inciden
| ts_...
| eddythompson80 wrote:
| 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.
| kergonath wrote:
| And all these places are easier targets with more people.
| masklinn wrote:
| 2 dead (both United Pacific employees, I assume train crew)
| and 3 light injuries from a train crashing into a truck,
| derailing, and hitting a building I think is pretty good
| evidence that using a train as your kinetic delivery is not
| a great way to do terrorism.
| sofixa wrote:
| There is, in Spain you have mandatory luggage control before
| boarding high speed trains. I think it was implemented
| following this massive terrorist attack in 2004:
| https://en.wikipedia.org/wiki/2004_Madrid_train_bombings
| amelius wrote:
| I don't think luggage control will do much. Train tracks are
| hundreds of kilometers of practically unprotected attack
| surface.
| tgsovlerkhgsel wrote:
| 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.
| WeylandYutani wrote:
| The easiest target is plowing into a crowd with a car. Learning
| how to drive train is beyond the unhinged morons.
| wat10000 wrote:
| This story is a good example of one major reason: trains are
| way more robust. Imagine a similar catastrophic fire in the
| cockpit of a high speed train. Worst case, you hit the
| emergency stop and then evacuate the train. The only person who
| would be at risk would be the train driver. Have that fire in
| an airplane and everyone on board dies.
|
| This incident wasn't a terrorist attack, but the same idea
| applies there. The Lockerbie bomb, for example, was pretty
| small. Setting it off in a train might have killed some nearby
| people, but that's all. But set it off in an airplane and you
| can kill hundreds.
| masklinn wrote:
| > Worst case, you hit the emergency stop
|
| You don't even need to do that, because most trains and
| pretty much every high-speed train has some sort of dead
| man's switch, so the driver leaving their seat would
| automatically enable emergency brake in short order as they
| would if the driver had e.g. fallen unconscious.
| user_7832 wrote:
| Another reason is, security checks are just one part of the
| whole process involved. A flight with 100 people dying because
| of a bomb may be more "glamorous" than 200 dead on a train to a
| terrorist organization.
|
| Also: the _actual_ number of such people /organizations, is,
| fortunately, extremely low in daily life.
| happosai wrote:
| Because security at airports is mostly security theater to make
| passengers feel safe.
|
| People are generally not afraid of terrorists hijacking or
| bombing trains, so security theater isn't necessary there.
|
| Bruce Schneier book "beyond fear" is over 20 years old and not
| outdated a bit.
| ordu wrote:
| _> if it was a coverup, then the EAAID gave away its own game by
| attaching the BEA's comprehensive findings._
|
| I'd say, that EAAID had written the report in a way to make the
| coveraup unmistakable. I mean, the reasoning is not just bad, it
| contradicts to itself in a way, that to my mind one couldn't
| achieve without a deliberation. So it is possible that EAAID was
| forced to support the hypothesis but resisted it in the only way
| it could.
| ec109685 wrote:
| Besides not agreeing with the EAAID, nothing in then BEA report
| makes Egypt look bad. It was a tragic accident and the crew
| acted admirably.
|
| What was the motivation for Egypt to insist on a bomb
| detonation beyond them believing that is what happened?
| unyttigfjelltol wrote:
| I assumed the lavatory alarm sent the Egyptian commission
| irretrievably down the wrong investigatory path, and couldn't
| be pulled back.
|
| That said, answering your question, an alternative
| interpretation would read quite a lot of missing context from
| the pilot's final words on the CVR:
|
| > For several seconds, the weak sound of breathing continued,
| followed by the thud of an object falling to the floor. And
| then, uttering the last words of flight 804, words heard by
| no one save for that lonely sentinel, the CVR, he said, "[I]
| ask forgiveness from God."
| elashri wrote:
| > "[I] ask forgiveness from God."
|
| That's too much reading by a western observer who doesn't
| understand the religious and cultural aspect of things.
| This could mean anything from "hoping that God will help us
| in this difficult situation by admitting your sins" to
| someone who realizes it is almost the end and as someone
| who believes in after death then they want to ask
| forgiveness in the last moments.
| selimthegrim wrote:
| The last part of the sentence is correct, but the
| EgyptAir 990 crash gave it a bad cast in Western eyes.
| ndiddy wrote:
| The article and French report point to the fire being caused
| by an oxygen leak from a faulty cockpit oxygen mask system.
| There were many problems reported with the system on that
| plane, such as the oxygen air level decreasing every flight
| and the oxygen mask box being replaced with a refurbed faulty
| one from another plane after it was found to be stuck open.
| Additionally, there's allegations of other problems with the
| plane in question not being logged properly. I think having a
| plane full of passengers on the state-run Egyptian airline
| getting killed due to poor maintenance is enough of a
| motivation for the Egyptian government to try to cover things
| up.
| qingcharles wrote:
| This is wild to me: "Even though passengers have
| been forbidden from smoking on airplanes for 25 years, the rules
| about smoking in the cockpit are less straightforward, and
| international regulations appear to invest the captain with the
| authority to decide whether smoking will be allowed or not."
| eddywebs wrote:
| Sounds like rule made by smoking captains for the smoking
| captains.
| lazide wrote:
| It's good to be the king?
| eadmund wrote:
| Why is it surprising? There's no danger from smoking on-board;
| banning it was never about safety.
| PanMan wrote:
| There is a danger, but not a direct danger (of the plane
| crashing). It certainly isn't healthy :)
| woliveirajr wrote:
| https://en.m.wikipedia.org/wiki/Varig_Flight_820
|
| Yes, it was about safety.
| protimewaster wrote:
| It feels pretty obvious that discouraging fire in a fully
| enclosed space would have safety as a motivating factor, so
| I'm surprised that multiple people here are arguing that
| there's no safety component.
| Rebelgecko wrote:
| It seems like the corrective action was just to add ash
| trays? Interesting how the pilot later disappeared without
| a trace tho
| wat10000 wrote:
| You just read about dozens of people being killed by an on-
| board fire and you're going to say there's no danger from
| casually having a fire on the end of a stick? Even if this
| one wasn't started by a cigarette, they certainly can cause
| fires.
| qingcharles wrote:
| Smoking on flights sucked. The whole cabin ended up hazy and
| choked with smoke. It stank. I hated those little ashtrays
| full of nasty ash and gum in the armrests. There are more
| than just the obvious safety reasons to ban it.
| NBJack wrote:
| You've got multiple sources of pure oxygen on board, and
| potentially hundreds of passengers counting on a safe flight
| in a metal tube hurling through the sky thousands of feet off
| the ground at hundreds of miles an hour.
| stall84 wrote:
| This had all the tone from the outset to just be narrowly
| focussed on this crash-investigation alone, but the writer did
| dedicate a paragraph to Egyptair Flight 990 from 1999.. An
| incident that really was one of the first modern airline pilot-
| suicide's that has never (The NTSB's conclusion) been agreed upon
| by Egypt. And in the past couple of decades that number has risen
| at an alarming pace (LAM Mozambique Flight 470 2013, Malaysian
| Airlines Flight 370 2014, Germanwings Flight 9525 2015) < That
| extremely frightening and tight grouping of incidents seems to
| have been followed by a few years of normalcy. Then most recently
| the China Eastern Flight 5735 that China is still apparently
| working on a report for, but don't expect much in the way of
| admission on China's part, of course. But at any rate, there is a
| noticeable problem in the corps of pilots being selected to fly
| for several airlines, even really good airlines.
| robocat wrote:
| Suicide is more common than we measure and can be impetuous:
| Three days after a publicized suicide, automobile fatalities
| increase by 31%. The more the suicide is publicized, the more
| the automobile fatalies increase. The age of the drivers is
| significantly correlated with the age of the person described
| in the suicide story. Single-car accidents increase more than
| other types just after the publicized suicide.
|
| https://www.jstor.org/stable/2778220
| coredog64 wrote:
| For political reasons SilkAir 185 was ruled inconclusive, but
| it was almost certainly pilot suicide. Similar to the earlier
| Egyptair case, the Indonesian authorities were very hostile to
| the evidence that pointed in that direction.
|
| https://en.wikipedia.org/wiki/SilkAir_Flight_185
| eadmund wrote:
| > there was no evidence that the pilots of flight 804 smoked
| during the flight. But even though the BEA found that a cigarette
| didn't cause the fire on flight 804 ... the BEA recommended that
| EASA examine these risks and amend regulations as necessary
|
| Smoking had nothing to do with this incident. Their own testing
| showed that holding a cigarette in the oxygen stream was
| (surprisingly) not dangerous. The only risk from cigarettes they
| found was deliberately trying to light oxygen tubing with a
| cigarette.
|
| And yet, despite a complete lack of both relevance and evidence,
| they included a recommendation to clamp down on pilot smoking.
| Anti-smoking is hysteria.
| wussboy wrote:
| This is the second pro smoking post I've seen of yours on this
| thread. A curious stance to take.
|
| Could a cigarette fall into the mask stowage box and rest
| against the oxygen tube thus creating a fire? Yes, it could.
| The entire and complete elimination of this risk is simply
| solved by forbidding the pilots from smoking, which is already
| forbidden to the entire cabin crew and passengers. What's the
| big deal? Who is harmed by not allowing pilots to smoke?
| gus_massa wrote:
| Why do they use pure oxygen tanks? Isn't it possible to use a mix
| of oxygen and nitrogen? Doesn't divers use a mix?
| croemer wrote:
| At high altitudes you need pure oxygen to get appropriate
| partial pressure of oxygen.
___________________________________________________________________
(page generated 2024-12-25 23:01 UTC)