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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

#121

Post by wat10000 »

CamperBob2 wrote: post #119
wat10000 wrote: post #110

Earlier quoted context omitted.

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 sh…

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.

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.

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

#122

Post by NBJack »

eadmund wrote: post #95
qingcharles wrote: post #72

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."

Why is it surprising? There’s no danger from smoking on-board; banning it was never about safety.

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.

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

#123

Post by buildsjets »

cyberax wrote: post #40
dmckeon wrote: post #6

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.

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…

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.

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

#124

Post by coredog64 »

stall84 wrote: post #76

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 47…

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

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

#125

Post by ndiddy »

ec109685 wrote: post #107
ordu wrote: post #67

> 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 o…

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?

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.

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

#126

Post by Rebelgecko »

woliveirajr wrote: post #103
eadmund wrote: post #95

Earlier quoted context omitted.

Why is it surprising? There’s no danger from smoking on-board; banning it was never about safety.

https://en.m.wikipedia.org/wiki/Varig_Flight_820 Yes, it was about safety.

It seems like the corrective action was just to add ash trays? Interesting how the pilot later disappeared without a trace tho

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

#127

Post by cyberax »

userbinator wrote: post #74
cyberax wrote: post #60

Earlier quoted context omitted.

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 i…

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.

Not really. Adding oxygen for sure won't help. Also halon is stored in extinguishers as a pressurized liquid, not gas.

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

#128

Post by selimthegrim »

elashri wrote: post #117
unyttigfjelltol wrote: post #116

Earlier quoted context omitted.

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, utterin…

> “[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.

The last part of the sentence is correct, but the EgyptAir 990 crash gave it a bad cast in Western eyes.

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

#129

Post by sgerenser »

buildsjets wrote: post #120
dmckeon wrote: post #6

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.

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 t…

Thanks for the real world information! Username checks out.

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

#130

Post by userbinator »

FridayoLeary wrote: post #69
wk_end wrote: post #65

Earlier quoted context omitted.

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.

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). F…

instead of being on by default during the flight but i assume the current procedure exists for a reason.

Suppose it fails the other way --- pilot needs oxygen but the valve refuses to open. I think they definitely did a risk analysis and came up with the current design, reasoning that the increased risk of an oxygen fire would be less than the risk of a pilot suffocating if the system failed the other way.

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