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Fire is the more worrisome threat. Luckily the terrorists don't seem to have cottoned on to this.

fast fourier transform wrote:

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Yeah, fire in an enclosed space with tons of jet fuel nearby is something to worry about. Though, iirc materials in the plane are tested to be self extinguishing or at least resistant to burning, the passengers and their stuff are not. I wonder what a terrorist with the appropriately flammable attire and/or a burnable carry on (say stuffed with flammable synthetic clothes?) would do...

They are resistant to ignition but not to propagation. All that's needed is an accelerant. Once there is a flame it will propagate throughout the aircraft at a normal rate, as if the material wasn't flame retardant. Back at university I did my dissertation on the Toxic Products of Aircraft Interior Fires. Let's just say that it scares me to think about, and I love flying! The retardant used in chairs, for example, itself contains many harmful chemicals. The ppm of hydrogen cyanide within an aircraft interior fire I measured as being over 23 times the amount which would lead to incapacitation within 15 minutes - the standard unit (COSHH15) - which essentially means almost immediate incapacitation... around 1 or 2 breaths and you're gone. Hydrogen chloride... mustard gas by another name... was over 460 times the 15 minute incapacitation amount - immediate incapacitation, with death to follow very shortly after. Other gases released... very scary stuff. It didn't even take much to burn it, a very small amount of kerosine - around 100gms. Of course getting even that small kerosine on a plane would be difficult for the terrorists but there are loopholes which I won't discuss here that in fact make doing so perfectly legal and perfectly easy.

If you're interested in the effects of an aircraft interior fire you need look no further than the British Airtours flight KT28M. If you're VERY intereste I can even send you my dissertation, although I warn you it's 3 years old and was done in 6 days and 5 nights with lots of coffee and a grand total of 1 hours sleep, so thereare a large number of typos!

Well there is foam insulation in the seats, for example, which does mean that it takes a little longer for the fire to propagate but if said fire were to occur in flight, particularly in a secluded space such as a fire cause from wiring may be, such a fire would get out of control soon enough before it could be fought. Everybody would die, no question. Also, things like the towels that everybody gets are extremely hazardous. Flame retardant they may be but, as mentioned, they will burn perfectly well once they get going, which it is perfectly easy to do, and they give out horrendous amounts of toxic fumes. One of the major aspects that I picked up on during the research I conducted was that withing a minute to a minute and a half, there was enough particlate smoke to completely obscure vision - imagine being in an aircraft on fire, unable to see for the thick black smoke, your face, eyes and throat burning from the acid, your skin burning from the huge heat of the fire, your lungs feeling as if they have been solidified from the Hydrogen Cyanide and Chloride, many other horrible, horrible toxins each of fatal doses in the air, including toxins that induce heart attacks! Feeling arouvd in the dark, petrified and confused, everybody pushing each other to try to escape. One minute... it's not a long time.

Keeping on the one minute theme, although seats, etc. have foam which prevents a more rapid propagation, I recorded the highest level of released gases (directly proportional to the highest temperature during the fires that I created) after exactly 60 seconds. The huge amount of Carbon Monoxide released, due to the slow method of burning, actually meant that this high level of concentration lasted for more than 3 minutes before it began to drop slowly away, eventually going from maximum at 4 minutes ater the fire (actually it was at maximum for the duration 1 to 4 minutes) to half 6 minutes after. These figures for CO are similar to those of most of the gases released, save for 1,2,4-Trimethylbenzene, which began churning out huge amounts after 5 minutes, peaking after 9. So even once most of the gases have finally been expelled to the outside, you then get another more than 11 minutes of fairly consstently lethal dosage of C9H12, as well as various others I didn't test for.

I performed these tests using a standard 40kg/hr rate of air flow to simulate the general cabin air change, a full change of air taking place every 2 and a half minutes. I recorded lethal levels of Carbon Monoxide, Sulphur Dioxide, Acetaldehyde, Ammonia, Hydrogen cyanide, Hydrogen chloride, Hydrogen fluoride, Acetic acid (this is particularly incapacitating as it burns the eyes and face terribly making it even more difficult to escape), Formaldehyde, Acrolein (this I associate with the blankets we all curl up in when it gets a bit chilly.. 2ppm (parts per million) are considered dangerous, I measured up to 331.9ppm after 1 minute dropping to a relatively lower 90ppm after 6 minutes... do you still feel snug?), Naphtalene (predominantly from the flame retardants, peaking after only 4 minutes), 1-Ethylnaphtalene, Benzene, Toluene, o-Xylene, p-Xylene (peaking after 8 minutes, most likely from flame retardant object, probably plastics... the life jackets I believe would contain a lot of this), 1,2,3-Trimethylbenzene and ,2,4-Trimethylbenzene. These are only of the gases I actually tested for. Add to these the particulate matter and let's not forget the heat (temperature peaked after 60 seconds at about 270 degrees centigrade and stayed on the floor, 220 degrees centigrade in the middle and 435 degrees centigrade on the ceiling, staying at these temperatures for around 3 minutes), and you have the one thing about flying which actually scares me.

Another point of note is that people tend to get low to the floor during a fire due to the ceiling being incredibly hot - also one of the first effects of hydrogen cyanide will be, aside from severe burning to the eyes, throat, lungs, inability to breathe, etc., the sudden onset of weakness in the legs, meaning many people, upon their first breath, will likely fall to a crawl... unfortunatey hydrogen chloride is denser than air, as I'm sure you know, so all of these people will be crawling around in a terribly dense pool of chlorine gas.

The point of fire retardents is 1. to make flames less likely to ignite and 2. to slow the speed of the burning. However, the effects of toxic gases are equal to exposure time multiplied by the ppm. It doesn't matter whether it takes a little longer, it will have the same effect. Even if it didn't, I measured fatal levels of Chlorine and Cyanide after less than 1 minute so this serves to prolong these levels. My fires laster for, at maximum, 16 minutes. This is without any additional fuel other than the initial 100gms of kerosine and the aeroplanes themselves. With additional fuel from the central fuel tank, wings, stabilators, etc., this doesn't bear thinking about. As for ignition, all you need is an accelerant.