Schneier on Security
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October 9, 2007
Methanol Fuel Cells on Airplanes
Methanol fuel cells are now allowed on airplanes. This paragraph sums up the inconsistency nicely:
In some sense, though, that's missing the point. Read the last restriction again. So now, innocuous gels/liquids/shampoos are deemed too hazardous to bring inside the airplane cabin, but a known volatile liquid (however safe it may be) is required to be stored inside your carryon baggage? I'm not criticizing the technology here, but I have a feeling that that this DOT logic is going to be questioned repeatedly by frazzled flyers.
Posted on October 9, 2007 at 6:24 AM
• 18 Comments
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Methonal is available in quite a few liquids and containers you will find on aircraft any way.
Although flamable it is generaly not that much of a risk compared to many other hydrocarbons commonly found (for instance butane in lighters and cans of hairspray / shaving foam / deodarant etc, also aftershave etc).
It depends on the quantitiy and at what temprature it is at and also the Lower and Upper Explosive limits at the cabin preasure and oxygen level (Quite low on some flights acording to various pilots associations).
As for medical side effects it has been found recently that the air intake systems on some aircraft are very unfortunatly co-located with the engines. This design flaw alows the air to be very easily contaminated with a whole range of quite nasty chemicals used in fuels and lubricants (again pilots and aircrew associations have complained about this).
As for the terorist threat, not very great it is an accelerant but not particularly a good one, and there is more than enough alchol etc on a comercial plane already if you wanted to go down that route.
The simple fact is that nobody in the public domain has so far come up with a collection of liqud chemicals that would be effective enough to be used in a way to endanger the aircraft.
Is it still the case that you can still order alcohol (hard liquor with a high alcohol content) on a plane?
So you can't bring shampoo on board, but you can ask for a flammable liquid and they will deliver it to your seat. The methanol in your carry-on bag is less of a problem than this.
A liquid does not have to be dangerous enough to take down a plane. All it has to do is cause alarm; this is the main goal of terrorism.
Note that this is a DOT approval; DHS and TSA are still to be heard from. Transportation is effectively just following an earlier ruling from the International Civil Aviation Organisation. While the practicality and economics of the fuel cell are untested, there's little question that they would be inherently safer than lithium ion batteries.
By the way, none of the fuel cell designs I have seen anticipate pouring liquid methanol into a fuel cell. The liquid fuel is stored in cartridges that pop into the fuel cell.
>So you can't bring shampoo on board ...
Well, actually, you can't bring something that you claim is shampoo on board. Big difference. At least with the whiskey, the cabin crew is fairly sure its actually whiskey.
This enables fuel cells to be brought on board, but it doesn't say anything about fuel. So you can bring your full laptop battery, but presumably no additional methanol.
The restriction on voltage and wattage is a practical limitation on the size of the fuel cell and fuel container. For a laptop battery, we are talking of a magnitude of 100 ml. If you come in with "60 watt fuel cell" attached to a 5 liter methanol tank, you might still rise some eyebrows.
In total, this does not allow you to bring significantly more methanol than you can already smuggle on board easily in a few 100 ml spray cans as part of your toiletry bag. But it is a pragmatic policy to allow transportation of fuel cell powered devices.
"As for medical side effects it has been found recently that the air intake systems on some aircraft are very unfortunatly co-located with the engines. This design flaw alows the air to be very easily contaminated with a whole range of quite nasty chemicals used in fuels and lubricants"
There are good reasons for taking compressed air from the engines, see:
Granted it would be better not to include the chemicals!
Usefully your Wiki link gives links (in the "Criticism" section) to the organisations complaining about the medical effects of air drawn over heated synthetic engine oils etc.
Saves me having to dig them out 8)
The hardest liquor that they are likely to carry on board the average aircraft is 80 proof, nowadays. Thus at 40% alcohol, you're talking about something that's nearly 60% water. (There may be an airline that carries 100 proof bourbon, 104 proof Scotch or 151 proof rum, but I'm not likely to fly on it.)
Contrary to what the article suggests, inhaling methanol fumes won't make you go blind. Otherwise, there would be an awful lot of blind ex-pit-crew-members from the days when Indy-car-type racing used methanol as a fuel.
One unpleasant feature methanol *does* have is that if it catches fire, the flames are all but invisible in daylight. OTOH, unlike most liquid fires, you can put it out with plain old water. (Again, referring to Indy car racing, if there was any indication that fuel had spilled and caught fire, the procedure was to fling bucketfuls of water all over the general vicinity, rather than stopping to try and pinpoint the actual fire.)
Solution: Have everyone put on Hospital examination clothes for their flight.
All luggage would be forced into a separate Cargo only plane or by ground.
The rules and security are ineffective at best. By being ineffective they endanger anyone who travels or is in the path of the plane.
This solution while admittedly odd would solve the problem.
I disagree; it's quite plausible to take down an aircraft with liquids. The truly silly part is that they ban liquids while allowing solids, which is an easier state of matter in which to package effective, compact explosives.
Until someone thinks of infiltrating the supply chain for Hospital gowns and replaces them with something suspicious enough to ban them, too.
>Solution: Have everyone put on
>Hospital examination clothes for their
Exam gowns would make effect garrots.
Please try again.
Put everyone naked inside a little box with a hatch which they could have their in-flight meal passed through. Add a couple of pipes to remove bodily waste.
Make the boxes see through, but load them onto the plane with privacy partitions between them. we could probably cram more people on per plane this way too.
Disallow carry-on baggage and put the fully checked baggage on a different plane.
Nursing mothers won't be allowed to travel.
Of course on some flights they wouldn't bother with the privacy partitions... But charge a premium for this "service"... :-)
Try traveling in the company of small children without food, drinks, books, toys, or other forms of entertainment. Now get stuck on the tarmac for 12 hours. Me, I'd prefer the terrorists...
Now you want to do this with adults, naked, with no newspapers, magazines, books, computers, etc. Stuck on the tarmac for 12 hours... That's going to be... Hmm. I can see where my choice of traveling partners would be really important!
Wouldn't it simply be safer for the airlines to provide electrical power for laptop users?
In addition to being safer, you'd think economies of scale would apply too.
> The simple fact is that nobody in the public domain
> has so far come up with a collection of liqud chemicals
> that would be effective enough to be used in a way
> to endanger the aircraft.
Umm. You could gas the passengers & crew... Remember chemical weapons from World War I?
The fear of "volatile liquid" that Bruce quoted in his blog entry is irrational and symptomatic of poor science education. After all, water is a volatile liquid.
I agree that the existing carry-on regulations for liquids and gels are stupid. I am totally unable to rationalize the confiscation of my 4.5-ounce tube of toothpaste that was 3/4 empty. However, I see a valid distinction between methanol, identified as such, in a sealed cartridge of readily recognizable design, and an arbitrary tube or bottle looking like one of hundreds of thousands of personal care products that even if labeled may or may not contain what its label says.
There's good reason to have the methanol in the cabin -- to power a computer on an airplane -- and the quantity allowed is too small to cause any serious damage, especially at reduced cabin pressure where explosive limits are narrow. So, much as I'd like to see the liquid/gel ban relaxed more broadly, I don't see a significant inconsistency here.
If we want to ban everything that can be hazardous to flyers, we'd better start by banning airplanes.
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