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5 April, 2008

Basis of the war on moisture - feasible?

The prosecution case against eight alleged terrorists has finally revealed the nature of the threat which led to a global ban on liquids in air passengers' hand luggage.

Commenters at Bruce Schneier's blog, some of whom are professional chemists, have examined the credibility of assembling liquid explosives from the reported components, and of performing that task in-flight.

The conclusions seem to be that:

  • In this instance the methodology was flawed, but it highlights a technique which others could use successfully. I'm sure there are people who'll mock this specific plot, and understandably so, but that's missing the point – the basic concept isn't ludicrous.
  • That even the improved methodology would produce an explosive probably of insufficient potency to destroy a plane.
  • That a minor but marginally credible risk has been massively overstated; that the handling of the risk is security theatre, more to do with authorities wanting to be seen to be doing something than about actually doing something worthwhile, but the risk itself isn't outright fantasy.
This also explains why I've been stopped by security officers interested in the number of 'AA' batteries I carry when travelling abroad (12 recyclables, for my camera), as it seems that's a way the chemical detonator could be smuggled aboard.

Ultimately, it seems to have been proved that the threat is possible. The core question is whether it's likely – whether it justifies a highly-visible worldwide 'war on moisture', or whether that policy is self-serving. That's still to be proven.

And no, I don't think "better safe than sorry" is adequate justification. By that argument, all passengers should be handcuffed and sedated for the duration of each trip.


My cynical side says that the war on liquids will last indefinitely due to the number of people making (from security companies to airport retailers) who are making money from it.

Expect the same to happen to batteries; you'll have to buy batteries at the airport, then throw them away for the return trip.

Since the stalinist thug John Reid went on the rampage, I have given up flying; I find the security theatre, far from giving me a sense of security, makes the experience so oppressive and threatening that it's not worth it.

Posted by Tim Hall at April 5, 2008 01:07 PM

"By that argument, all passengers should be handcuffed and sedated for the duration of each trip."

... so the last thing you remember before drifting off to sleep (for the duration of a loooong boring flight) is being handcuffed by an air stewardess ... i can think of worse things!

Posted by jonp at April 5, 2008 01:13 PM

actually, all the professional high-yield explosives in the US (eg, used by police & FBI explosives specialists) are (clear) liquids, with slightly higher post-mix yield (by volume) than dynamite. so 300ml is more than sufficient to bring down an aircraft and even 100ml could do it if used "sensibly", eg placed & braced against the fuselage by say wedging a vial between wall & chair leg on a window seat. they are stable at quite high temperatures in a normal-living sense (eg, under summer time california sun) both before and after mixing.

so, much though i loathe security-theatre, in this case it's a valid concern.

Posted by Saltation at April 8, 2008 11:27 PM

I'm no chemist, and I'm not sure how/where the bombs were supposed to be located, but my reading of the comments thread suggested that this technique wouldn't have produced a high-yield explosive.
But yes, virtually the same approach, using different chemicals, would be a real risk.

But how likely is it? Enough for security agencies to routinely guard against it on every flight? That's what I was questioning in the closing paragraphs.

Posted by NRT at April 9, 2008 08:56 AM

2 legs:

1st, re schneider's post's comment thread & "no high-yield explosive": nearly all the commenters have little or no practical experience (& the chemist is merely someone with a phd in chemistry, not someone familiar with getting _precisely_ the right mix of chemicals to go bang). however, there are 4 key comments there which ARE by practised explosives people. and they all emphasise that 100ml of transparent liquid, stable and safe to transport casually, is quite enough to take down a plane and can be rendered effective without sequestering yourself in a well ventilated bathroom with a bucket of ice.

key snippets:
"Some people are confusing deflagration and catalytic decomposition of peroxide mixtures with detonation. The way HTP is used as rocket fuel is not comparable to its use as an explosive. Proper HTP mixes are powerful and brisant high explosives, on a par with TNT or better."
"Channel 4 in the UK ran a recent "Despatches" programme on airport security. Bottom line was that it's all vapourware and designed to con the travelling public into believing that all the various security measures will make their journey safer.

What was really impressive was the explosive expert who filled two 100ml bottles (and so passable through security) with two different chemicals (not named), mixed them together in a bottle bought airside and then detonated. The explosion blew out the side of the airplane fuselage where they had set the exlosive device. So further proof of the inanity of the 100ml fluid limit."

2nd, re likelihood vs the costs of 100% protection.
yup. with you all the way.
it simply is TOO EASY to break things, and the methods used to FULLY protect vs them (or even just 99% reduce) are profoundly onerous on the general travelling public.

warping the intent of that military quote slightly: "he who defends everything defends nothing." without infinite resources (including time), you CAN'T fully protect against attack. as that last commenter finished with:
"No carry on, no hand luggage, naked passengers ...that might work" (and even then, you can immediately think of 2-3 ways to get round it...)

security theatre does have a very real point, though, in that the bomber-types tend to be bandwagonists and hysterical, rather than aspergic and rational. theatrical people overweight theatre. fight fire with fire -- create a meme that says that their meme's outcome will be caught. causing your enemy to choose not to fight is far more powerful than defeating him. a la "chilling effect". plus, these guys tend not to be experienced explosives experts iwith access to high quality chemicals. "frictional" controls might be easily circumvented by experts, but can usefully hamper idiots working with crap kit.

so i guess ideally you'd just quietly slacken things off after a while, after the fitna has subsided (assuming it does). the likelihood of attack drops and the probabilistically-weighted cost-benefit point shifts. all life-preservation work comes down to cost-benefit tradeoffs... just ask the nhs. ;)

but the planes-are-easy-targets realisation genie came out of the bottle irrevocably when the first plane hit the WTC. we can never again travel safely with the old casual security.

Posted by Saltation at April 10, 2008 12:20 AM

in other news:

"brisant" -- new word for me!!

Posted by Saltation at April 10, 2008 12:23 AM
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