are liquid explosives a real threat?

Factual Questions
1

I am just curious, are the liquid explosives that so concern the nice folks at airline security a real threat? I understand that they exist-lots of threats exist-but can a local terrorist obtain the raw materials, create the explosive, survive the ride to the airport, and board an aircraft with them? The dept of Homeland security thinks so:
http://www.tsa.gov/approach/mythbusters/liquids_ban.shtm

My question, based on comments I have read on places like Bruce Scheier’s crypto-gram newsletter, indicate that the successful production of a liquid explosive is so difficult as to not be creditable. Of course as long as there is any chance at all that these explosives can be created, and there is, there is a threat. But to be creditable this threat must be greater than other possible threats.

Is there a consensus on the subject?

2

At my workplace, we have occasional Friday seminars where speakers come in to address any interested employees on topics of general interest. We had an FBI explosive forensics expert come in to speak about terrorism about the same time that DHS implemented the “no liquids” rule and someone in the audience asked him the OP’s question. He claimed that 3 oz. of liquid explosives was more than enough to bring down an airliner, and that manufacturing such explosives might be difficult, but it would be possible for someone who understood organic chemistry and had access to some pretty common chemicals. I don’t remember his name, but I do remember that he worked on reconstructing the Oklahoma City attack to determine how much fertilizer was used, so his practical experience and authority seemed pretty credible.

3

One word–Nitroglycerin.

4

Most of the talk on ‘liquid explosives’ concerns acetone peroxide , as it was allegedly the explosive that the terrorists arrested at Heathrow last year were planning on using, the incident that precipitated the no liquids rule worldwide. Note that its not a liquid itself, its a solid, but it is prepared from two very common liquids - acetone and aqueous hydrogen peroxide.

I’m a chemist, and though I’ve never made acetone peroxide myself, I’ve spoken to people who have and the consensus is that its not credible to think that people could synthesise it in an airline lavatory. Actually, ref 15 in that wiki article gives a pretty good account of the difficulties involved - its a relatively slow reaction - a few hours, it stinks, and you then need to dry the solid explosive somehow, which will again be slow. Probably not impossible, but extremely improbable.

So, the entire world of air travel security being turned upside down on account of acetone peroxide doesn’t stand up to scrutiny. There may be other explosives assembled from common liquids that are more of a threat, but I haven’t heard what they might be.

5

[QUOTE=rbroome]

My question, based on comments I have read on places like Bruce Scheier’s crypto-gram newsletter, indicate that the successful production of a liquid explosive is so difficult as to not be creditable.
[/QUOTE]

Bruce Scheier is an expert in cryptography, not explosives or chemistry. And he appears to have some sort of anti-government ax to grind. I would take his musings with a grain of salt. Also, bear in mind, it is not necessary for people like him to be right or factually accurate. His purpose is to make the government appear foolish and reactionary.

It’s like people who say that current airport security is a joke or provides an illusion of security. Airline security has to balance between providing an impenetrable barrier and not having you wait 2 hours to board your plane.

6

[QUOTE=Bosda Di’Chi of Tricor]
One word–Nitroglycerin.
[/QUOTE]

Nitroglycerine by itself is generally too unstable as the terrorists would probably need to be concerned with not blowing themselves up during the manufacturing or on their way to the airport (ie don’t hit any pot holes).

7

Former airline pilot here …

Setting aside explosives entirely, flammable liquids are another massive risk.

A 1 qt booze bottle full of gasoline will start a fire in the cabin that we probably cannot put out. If we’re over inhabited terrain we can maybe get down to an airport before the fire destroys enough structure that the airplane comes apart in flight or before the cockpit environment becomes unsurvivable.

Note I said “cockpit environment”. We have separate air supplies, fancy anti-smoke gear, etc. We’ll last a lot longer than anyone in the cabin will. Still, we have a very few minutes, 5-10 tops, to find an airport, get down, get stopped & get off. That will require a lot of luck to go along with some skill & a lot of guts.

A cabin or cargo fire is the only scenario that ever kept me up at night. I’ll take an ocean ditching any day over a cabin / cargo fire.
I’m not an expert on explosives at all, but if fairly stable liquid explosives exist, then all the bad guys need to do is smuggle on enough using enough people each with separate containers & have somebody else bring on the detonator. They don’t even have to be very powerful if they can smuggle on enough.
The central folly of the current security mess is that until we focus on the intent of the passengers we’re largely chasing windmills. Any object is a threat in the hands of a threatening person.

8

[QUOTE=Bosda Di’Chi of Tricor]
One word–Nitroglycerin.
[/QUOTE]

True, nitroglycerin is a liquid explosive. But you’re not going to be able to synthesize it in the air. And you don’t want to carry it on as a pure liquid (you’d look pretty stupid blowing yourself up in the airport, even if you are a suicidal idiot), meaning you’d have to either freeze it and keep it frozen until you got it on board or you’d have to mix it with one of the other desensitization agents at which point you’ll probably need a detonator.

9

[QUOTE=msmith537]
Bruce Scheier is an expert in cryptography, not explosives or chemistry…His purpose is to make the government appear foolish and reactionary.
[/quote]
Not that they need much help with that. Duck & Cover!

[QUOTE=msmith537]
It’s like people who say that current airport security is a joke or provides an illusion of security. Airline security has to balance between providing an impenetrable barrier and not having you wait 2 hours to board your plane.
[/QUOTE]
The thing is, many of the current methods are demonstrably almost wholly ineffective.

[QUOTE=msmith537]
Nitroglycerine by itself is generally too unstable as the terrorists would probably need to be concerned with not blowing themselves up during the manufacturing or on their way to the airport (ie don’t hit any pot holes).
[/QUOTE]
Not true. Correctly purified nitroglycerin takes a significant shock–comperable to the impact of a hammer on a hard surface–to detonate by shock impulse. Its spontaneous thermal detonation point is more than 400 degrees F, and while you don’t want to be playing with flint and steel around it, it is substantially less sensitive to static discharge than many solid aluminized propellants. In short, you could walk around with a vial of the stuff in your pocket without a major risk of detonation; the biggest risk is that you’ll get a small amount captured between the threads of the cap and that will result in a friction-initated cascading detonation.

Nitroglycerin has other problems for terrorists, though; the corrrect grade of nitric acid (white fuming nitric acid) used in manufacture is pretty carefully tracked (albeit more for drug manufacture than explosives), the purification and thermal control processes are key in getting a usable, stable product, and the end result is readily identifiable both visually and by smell. It’s not an ideal product for terrorist application, although I daresay it could be pressed into service to blow a fairly large hole in a sensitive part of an airframe by someone sufficiently desperate.

[QUOTE=LSLGuy]
The central folly of the current security mess is that until we focus on the intent of the passengers we’re largely chasing windmills. Any object is a threat in the hands of a threatening person.
[/QUOTE]
Essentially true. Aircraft are not that robust and it would be easy for someone to do significant damage with objects readily smuggled or openly carried onto an aircraft. (I’m not going to go into specifics, but anyone familiar with the construction and operation of commerical airliners can easily come up with a varity of vulnerabilities.) The stupid thing about the September 11, 2001 attacks, however, is how utterly preventable they were. A closed, locked, secure flight deck isn’t just an obvious vulnerability, it’s one that is remediated in a straightforward fashion at a very modest price. Locks on the doors would have rendered terrorists wielding boxcutters unable to control the plane and limited to harming individual passengers. And yet, because the airline industry and the FAA was so utterly blind to this idiotic security lapse we now have to endure extensive and mostly useless restrictions that are all about closing the barn door after the horse has escaped.

To the o.p.'s question, liquid explosives are a threat, but probably not the most major one. Limiting the liquids that can be taken onto the plane is actually a fairly reasonable precaution in the scheme of things, but there are so many other vulnerabilities this is like rowing a life raft with a teaspoon.

Stranger

10

[QUOTE=Stranger On A Train]
Nitroglycerin has other problems for terrorists, though; the corrrect grade of nitric acid (white fuming nitric acid) used in manufacture is pretty carefully tracked (albeit more for drug manufacture than explosives), the purification and thermal control processes are key in getting a usable, stable product, and the end result is readily identifiable both visually and by smell. It’s not an ideal product for terrorist application, although I daresay it could be pressed into service to blow a fairly large hole in a sensitive part of an airframe by someone sufficiently desperate.
[/QUOTE]
Someone has attempted just that. As I understand it, Ramzi Yousef expected that the bomb would either cause a nearby fuel tank to explode, or make the plane unflyable. But the tank remained intact and an experienced crew brought the damaged plane down safely.

Yousef and his confederates were planning to bomb a number of other flights, but were found and arrested before that could happen. The fact that one group pulled this off with reasonable success but so far no one else has copied it would seem to me to mean that it may be possible, but it ain’t easy.

11

Taking “liquid explosives” not to mean explosive liquids, but rather explosives prepared from innocuous liquid precursors… Wouldn’t work. The solvents act as a stabilizer and application medium. The precipitate product doesn’t become explosive until dried.

What happens is that while people grumble about having to repackage their assorted toiletries into individual 3oz bottles in a clear plastic bag, a goodly portion of them get the impression that most of what the TSA does is something other than security theater and so feel safer than they would if unobtrusive security measures were used instead… even if they would objectively be safer with less ridiculous rules and regulations.

It’s also useful for conditioning people to submit to demeaning and capricious inspections of their person and possessions for no apparent reason.

12

[QUOTE=msmith537]
Bruce Scheier is an expert in cryptography, not explosives or chemistry. And he appears to have some sort of anti-government ax to grind. I would take his musings with a grain of salt. Also, bear in mind, it is not necessary for people like him to be right or factually accurate. His purpose is to make the government appear foolish and reactionary.

It’s like people who say that current airport security is a joke or provides an illusion of security. Airline security has to balance between providing an impenetrable barrier and not having you wait 2 hours to board your plane.
[/QUOTE]

I understand that he is not an expert in chemistry. But the chemists he quoted are (presumably. they weren’t quoted by name). He isn’t the only source of the information, just one that I respect a lot and could remember the name. I believe CNN produced a story with similar information shortly after the start of the liquids ban-but I can’t find the article.

13

[QUOTE=msmith537]
Nitroglycerine by itself is generally too unstable as the terrorists would probably need to be concerned with not blowing themselves up during the manufacturing or on their way to the airport (ie don’t hit any pot holes).
[/QUOTE]

The DHS seem to discount that as an explosive threat. At least that is what the director was quoted as saying. Not that it can’t be a threat, just that other liquids are more dangerous to aircraft. Even though it has been used in attempted aircraft bombings. But as has been stated, I believe it is too unstable to smuggle aboard.

14

[QUOTE=rbroome]
I understand that he is not an expert in chemistry. But the chemists he quoted are (presumably. they weren’t quoted by name).
[/QUOTE]

I don’t presume.

15

[QUOTE=Stranger On A Train]
Not that they need much help with that. Duck & Cover!

The thing is, many of the current methods are demonstrably almost wholly ineffective.

Not true. Correctly purified nitroglycerin takes a significant shock–comperable to the impact of a hammer on a hard surface–to detonate by shock impulse. Its spontaneous thermal detonation point is more than 400 degrees F, and while you don’t want to be playing with flint and steel around it, it is substantially less sensitive to static discharge than many solid aluminized propellants. In short, you could walk around with a vial of the stuff in your pocket without a major risk of detonation; the biggest risk is that you’ll get a small amount captured between the threads of the cap and that will result in a friction-initated cascading detonation.

Nitroglycerin has other problems for terrorists, though; the corrrect grade of nitric acid (white fuming nitric acid) used in manufacture is pretty carefully tracked (albeit more for drug manufacture than explosives), the purification and thermal control processes are key in getting a usable, stable product, and the end result is readily identifiable both visually and by smell. It’s not an ideal product for terrorist application, although I daresay it could be pressed into service to blow a fairly large hole in a sensitive part of an airframe by someone sufficiently desperate.

Essentially true. Aircraft are not that robust and it would be easy for someone to do significant damage with objects readily smuggled or openly carried onto an aircraft. (I’m not going to go into specifics, but anyone familiar with the construction and operation of commerical airliners can easily come up with a varity of vulnerabilities.) The stupid thing about the September 11, 2001 attacks, however, is how utterly preventable they were. A closed, locked, secure flight deck isn’t just an obvious vulnerability, it’s one that is remediated in a straightforward fashion at a very modest price. Locks on the doors would have rendered terrorists wielding boxcutters unable to control the plane and limited to harming individual passengers. And yet, because the airline industry and the FAA was so utterly blind to this idiotic security lapse we now have to endure extensive and mostly useless restrictions that are all about closing the barn door after the horse has escaped.

To the o.p.'s question, liquid explosives are a threat, but probably not the most major one. Limiting the liquids that can be taken onto the plane is actually a fairly reasonable precaution in the scheme of things, but there are so many other vulnerabilities this is like rowing a life raft with a teaspoon.

Stranger
[/QUOTE]

Thanks. That is the kind of information I was hoping for.

16

Earlier this year I was prevented from taking a 4oz bottle of perfume on a plane in the US. I had that and a 3.4oz bottle, which is the upper limit. I offered to pour out .6oz from the 4oz bottle down a sink to comply, only to be told it was the size of the bottle, not the amount of liquid in it, that was the problem :dubious: So I had to check in my whole bag for the sake of .6oz of air.

17

[QUOTE=msmith537]
I don’t presume.
[/QUOTE]

fair enough.
that is being a proper skeptic-and why I like the folks here so much!

18

[QUOTE=rbroome]
I understand that he is not an expert in chemistry. But the chemists he quoted are (presumably. they weren’t quoted by name). He isn’t the only source of the information, just one that I respect a lot and could remember the name. I believe CNN produced a story with similar information shortly after the start of the liquids ban-but I can’t find the article.
[/QUOTE]

If anyone is interested, a quick google for something like Astrolite™ will usually turn up something like this discussion - following up on the individuals and chemicals discussed will then lead you off into the wild and wooly hinterland of Blowin’ Stuff Up Real Cool. But my impression is that mixing up explosives from precursors on a plane is unlikely to meet with unqualified success. However since a qualified success would lead to filling the plane with toxic fumes, flames, screaming & terror I can sort of understand why they decided to prevent anyone trying it.
However, the rowing a boat with a teaspoon analogy is pretty good - there are so many other risks I really don’t know why they bother.

19

[QUOTE=slaphead]
However, the rowing a boat with a teaspoon analogy is pretty good - there are so many other risks I really don’t know why they bother.
[/QUOTE]
They bother because it’s both easy, and it highlights for the flying public that government authorities are “doing something” about transportation security. Never mind that allowing carry-on luggage greatly increases the load (and therefore the likelyhood of something sneaking by) on gate security personnel, and there are any number of ways that a barehanded person could significantly threaten an aircraft, not to mention any number of other attacks on public facilities which are essentially indefensible in an open state. In the end, it is really impossible to practically eliminate the threat of terrorist action.

There are, however, smart things you can do that are low-hanging fruit–such as securing the flight deck of commercial aircraft against casual intrusion–which make it much more difficult for someone who is only modestly trained or motivated to do badness. The fact that no major attacks have since occured on US soil indicates either a lack of skill or a lack of determination on the part of Islamic terrorists. Frankly, they don’t seem to lack for determination, so I’d say that the vast majority of warnings about “major, unspecified attacks” are little more than utter bullshit.

Restricting liquids carried on aircraft is a reasonable precaution. But one could readily defeat extant security measures by other methods if one were so motivated. The fact that no real attempt has been made to do so (other than the errant and unorganized moron) indicates that the emphasis on this thread has been vastly inflated. It exists, certainly, but the influence and capability is limited.

Stranger

20

[QUOTE=Jurph]
At my workplace, we have occasional Friday seminars where speakers come in to address any interested employees on topics of general interest. We had an FBI explosive forensics expert come in…
[/QUOTE]

OT, but that’s really cool! May I ask where you work?