I’d forgotten how much I liked the 90s USENET.
I wonder what sort of attack you could mount these days on an airliner. If you stand up and say “I have a bomb”, the other passengers will attack you. Prior to 9/11, I think most people felt that it was better not to resist a hijacker. On 9/11, when it became clear to passengers that they were going to be killed, they assaulted the hijackers. The same thing happened shortly thereafter to Richard Reed (sp?). It also seems like it would be difficult to smuggle some sort of incendiary device on board. Wouldn’t the explosive sniffers pick that stuff up? The metal detector would get thermite. It seems like airplanes have been done. I read an interesting article about an idea for a terrorist attack involving blowing up a dam upstream from some West coast city (which I can’t recall). If I were a terrorist, I would try to come up with something new. With regards to reasonable airline safety measures, it seems to me that the best thing to do would be to try to get as many air marshals on as many flights as possible. I don’t know how many there are right now.
My two cents,
Rob
Smuggling sufficient explosives or incindaries on board an aircraft to do major damage would be almost trivial for someone knowledgeable and well-equipped (which fortunately most would-be terrorists are not). “Explosive sniffers” (i.e. machine olfaction explosive detection) is still an emergent field, and while I’m not intimately familiar with the state-of-the-art, I doubt it can be considered foolproof in detecting all explosive compounds. Most traditional methods have focused on nitrate explosives, which are the largest class of commerical and military explosive compounds, but are not exhaustive. The more recent reading I’ve done on the topic indicates that research is actively being done on detecting other types of explosives; in any case, olfaction explosive detection is not applied consistantly and is not itself a sufficiently reliable or undefeatable method to assure detection with utmost confidence.
Federal Air Marshal placement is irregular at best. I suspect that they’re more likely found on flights originating from or terminating at airports servicing Washington D.C. and the metropolitan New York City area (and probably many foreign flights) but they’re rarely found these days on other domestic flights, even given the reduction in flights since 11 September 2001. Since the Federal Air Marshals were transferred over to the Transportation Secuirty Agency of the Department of Homeland Security they seem to have had difficulty recruiting and retaining experienced law enforcement personnel for this duty. And a single Air Marshal might deal with one or two attackers, but unlikely five or six. As a deterrent, the Air Marshals are more of a flag-waving measure than a significant force.
However, as noted, an attack upon or using commerical airliners was low-hanging fruit that has long since been plucked. While the precautions in place are insufficient to deter a trained, determined adversary, they certainly make it more risky for a successful action by amateurs. It doesn’t appear, however, that there are many who have ready access to the continental United States and are willing to sacrifice themselves.
However, your thoughts upon blowing up a dam are pretty misplaced. For one, most operating dams are, for obvious reasons, not placed above major metropolitan centers, and while the destruction of a reservoir could cause a major disruption on water supplies you’re unlikely to see deaths in the thousands. Second, it would take way more than a few pounds of explosives–even the sort of high order demolition explosives that would be difficult for a foreign national to obtain through legitimate channels–to damage a large dam. Dams are designed with large safety factors and seismic events in mind, and the catastrophic breeching of a dam would likely require several thousands of pounds of high exploives placed in a specific location, requiring many orders of expertise beyond, say, driving an explosives-laden passenger car into a public sporting or shopping venue.
It is our (US) great fortune to live in a region geographically and politically isolated from (most) extremists who are willing to go to such lengths to commit acts of terror. This should not be confused with the effectiveness of deterrent efforts, which are necessarily only effective where opponents are not generally desperate enough to resort to extremes. In Iraq, no methods have been genuinely effective in stopping terrorist/insurgent attacks, and in Israel, only a well-armed populace, a near-police state level of border security, an aggressive stance toward insurgency, and a measure of acceptance of a certain level of constant risk (i.e. siege mentality) has allowed them to cope with the ever-present threat of action against civilians.
Stranger
I’m at the JHU Applied Physics Lab. It’s a pretty cool place.
So what is the TSA’s reasoning behind having us put all our liquids in small containers in a plastic bag and presenting them for screening separately? Is it just to restrict the total volume of liquids on board, and making us “declare” them keeps us from boarding with a carry on bag full of liquid explosives - and they would see that on the x-ray screen anyway, right?
It’s not like there’s a sniffer in the x-ray machine that checks all those quart-size baggies full of shampoo and mouthwash, so what’s the deal with the segregation and special screening for the liquids?
If I were a terrorist with access to a stick of dynamite, I would crumble it up into dust, mix it with e.g. sand or oatmeal, and then walk around the ground-side of a major airport or two during busy times sprinkling the mixture on the floor a la The Great Escape. As people went through to security, every nitrate sniffer in the terminal would light up like the jackpot, and hundreds of innocents would get the Gitmo treatment, by which time I’d be fifty miles down the road.
Segregating them out in a plastic bag does make it easier for screeners to limit the quantity of liquids taken on board. However, as you note, they’re not doing any special detection on the liquids themselves, and it would be relatively easy to defeat the system by any of a number of means. Like I said, it’s rowing a liferaft with a teaspoon. But from a technical security standpoint, it’s a valid step. It’s just one that sucks when you get on a flight that doesn’t have drinks service.
You wouldn’t even need to use dynamite; any compound with nitrates (or other substances that are being detected for) would probably work, e.g. fertilizers, paint additives, et cetera.
However, from experience I have reason to believe that the detectors aren’t even all that reliable to begin with, and the number of “false” positives you get might not even be all that high, which makes me question their value in making true positive identification. But it’s pretty funny to watch people walk into them and get all surprised by the puffing air, and they look all impressive with flashing lights and an authoritative voice telling you what to do, so it’s at least good theater.
Stranger
So don’t try to bring it to an airport if you have to drive on a freeway in Pennsylvania or California to get there. They have potholes that are bad enough to do it.
FYI, here is the dam plot I was talking about: link
FWIW,
Rob
Scene 8: Planes are closing in on the “target” and the rocket launcher crew goes to work. With precision they strike lookout and defense positions on the dam, then target the office structures below. As they finish, a cargo jet approaches from the North at high velocity, slamming into the back side of the dam just above the waterline and exploding, shuddering the earth. A large portion of the center-top of the dam is missing. Within seconds a cargo plane coming from the South slams into the front face of the dam, closer to the base, and explodes in a blinding flash, shuddering the earth. In moments, the dam begins to fail, and a final volley from four rocket launchers on the hill above helps break open the face of the dam. The 40-mile-long Lake Roosevelt begins to pour down the Columbia River Valley, uncontrolled. No warning is given to the dams downriver, other than the generation at G.C. is now offline.
Setting aside some of the more obvious implausibilities (acquiring said airliners by the previously indicated method seems unlikely at best, given that they’re going to have to not only take out the crews of the aircraft but file a credible flight plan and convince ground control of their legitimacy), there are also other significant problems. First, they’re going to have to coordinate their activities “with precision.” There’s a huge difference between turning some surplus Russian RPG into a roadside bomb and performing “precision” strike activities.
Second, piloting a large airliner/cargo jet to “skim” the surface and hit “just above the waterline” would require piloting skill and experience of years. This isn’t just like hitting the runway; it’s like hitting the runway at just the right place (within 50’ or so) without landing indicators or Instrument Landing System assistance. If they miss, the plane either flies above the dam, doing no damage (but almost certainly impacting the area forward of the dam), or it hits the surface of the water and either skims off or breaks up, again likely doing no damage. The guy coming from the front of the dam has a much larger aspect to target on, but if he hits the base he’ll be impacting the thickest part of the dam wall (or the water below), or he’ll notch the top of the dam wall and do only modest, non-catastrophic damage.
Another problem, and one that may not be obvious, is how little damage a falling airliner or a man-portable rocket launcher will do to a large earthen-backed concrete structure. The Grand Coolee Dam would be a particularly undesireable target for such an attack; as a solid gravity dam it is essentially one thick wall that holds back the force of water behind it by sheer mass. An aircraft, on the other hand, is basically an aluminum can with wings. Imagine smashing an aluminum can against a cinder brick and you’ll get an indication of what kind of what kind of threat an airliner by itself is to a structure like a dam. Hardly an unstoppable object versus an irresistable force. Even the fire isn’t going to do much damage, as the dam has enough thermal mass to absorb any reasonable amount of heat.
As for explosives or rocket launchers, large concrete structures generally respond to sharp localized impact or impulse not by cracking through their thickness by spallation (shallow cratering) which distributes the energy across surface elements that are free to shear versus embedded elements which are constrained from shearing by the high pre-existing compressive forces. Compacted earthen-backed dams are even worse as they’ll generally absorb the energy and distribute it in a very uniform manner, doing little permanent damage. Basically, you’ll blow out a little crater of material, and the rest of the acousic energy from the detonation is reflected back outward.
The Ruhr dams that were destroyed by the British during WWII (see the book and film for more detail) were roughly comperable in construction and size to the Grand Coulee Dam, and it was a major and risky development project to construct a bomb and train bomber crews to destroy these dams, which included flying less than a hundred feet above the water, dropping the bomb at just the right time to delivery it just forward of the waterline, pulling up to avoid impact, and the pressure fuse designed to let the bomb sink to just the appropriate depth to assuredly destroy the structure of the dam. (That penultimate scene from Star Wars where Luke has to fly the trench and shoot a missile directly into an exhaust port? George Lucas essentially stole that verbatim from The Dam Busters.) This isn’t just more than a couple of guys with a bad attitude and tablecloth headgear are going to do; it’s more than a small organization of trained professionals could probably execute with any expectation of success.
There is “low hanging fruit” that terrorists in any free nation could exploit, but blowing up dams is beyond the means of any organization short of a medium-sized air force, regardless of how well funded.
Stranger
Forth paragraph should read “…large concrete structures generally respond to sharp localized impact or impulse not by cracking through their thickness but by spallation (shallow cratering) which distributes the energy across surface elements…”. In order to do real damage to this kind of structure you either need to deeply penetrate the structure (a la earth penetrating “bunker busters”) or use a shaped charge, and even those will have significant limitations with anything as massive as a gravity dam.
An arch dam like Hoover might be somewhat more subceptible, but they’re still built to such enormous safety factors that simply crashing an aircraft into them is going to be like hitting an elephant with a flyswatter. When dams fail, it’s rarely a fail of the structure of the dam itself but of the footing or abutment constraints, as with the infamous LADPW St. Francis Dam.
Stranger
Or Lex Luthor detonating a nuclear warhead nearby and triggering a major earthquake in the hope of sinking California into the ocean.