I should clarify that I think the TSA wants to prevent airline bombings (that is, loss of a plane) above all else. Hijackings are much more difficult than they were before 9/11, even if the terrorists were in a group and allowed some weapons. I don't think the TSA is, or should be, focusing on hijackings. AFAIK, since 9/11 there have been no more hijacking attempts, but several bombing attempts.

"I should clarify that I think the TSA wants to prevent airline bombings (that is, loss of a plane) above all else."

I have my doubts about that as well. I would think that the lack of K-9 teams near departure gates is a good sign that bombings are not the concern of the TSA when it comes to airport security. Bombings are probably a concern somewhere, but the security checkpoints do not seem to do much when it comes to stopping a bomb plot.

Keep in mind that private planes are exempt from the security checks. If a terrorist wanted to blow up a commercial plane, what would stop them from chartering a private jet, bringing bombs on board, and then ramming their explosive-laden plane into an airliner mid-flight? Why even bother doing it in flight? A terrorist might just roll their chartered jet into a fully-loaded passenger plane on the runway, and blow up a plane in front of a crowd of people.

Perhaps there is some other procedure in place to ensure that no bombs can make it past the numerous ways that people and vehicles can enter an airport without going through a security checkpoint. If that is the case, what is the purpose of the checkpoint? Why not just apply whatever techniques prevent terrorists from ramming private jets into airliners to the rest of the airport, and let us keep our rights intact?

It is also worth pointing out that there are lots of other bombing targets that are not being bombed, despite a complete lack of security. Anyone can bring large packages onto the NYC subways without any harassment or scanning, yet those trains (which are packed with hundreds of people during the rush hour) have not been blown up. A truck full of explosives could easily drive onto a major bridge. Yet despite these clear vulnerabilities, and despite the fact that other countries see such attacks and more, we rarely have them here. Are airlines really more special targets for bombers than urban transit systems?

As has been pointed out before, an explosion in an airport would be bad but the damage would be pretty localized and everyone knows where the airport is, there are lots of emergency facilities in palace because they always have to be prepared for the possibility of crash landings or other accidental disaster.

An explosion in the air, or abuse of the plane as a missile as happened on 9-11, is a much bigger problem because the potential destructive radius is much larger and the area of incidence much less predictable. The costs of that happening in a city center in 2001 were staggering; likewise, consider the economic impact of an airliner plunging into or blowing up over a nuclear power station, which might result in less actual destruction but far more severe public panic and economic disruption.

I pointed this out elsewhere, but a rush hour subway train in New York City carries over two thousand people (and that is assuming that the train is not over capacity), nearly as many as were killed in the September 11th attack. One well-timed, powerful bomb could kill almost everyone on such a train, and if it were detonated while a second train was passing by even more people would be killed. These trains travel over major bridges and under important buildings; the damage of such an attack could be enormous.

It has not happened yet, and hopefully it never will happen. The bomb itself would probably be difficult to procure and transport to New York City without being detected by an intelligence agency. What we can say is this: body scanners, luggage X-rays, and shoe removal have done nothing to prevent such an attack, because no such measures are in place.

Such bombings as you describe have taken place in London, Madrid, and arguably Japan, to cite just a few. They certainly cause a lot of damage, but you can harden fixed infrastructure and to some extent this has already been done, since subway/rail operators already deal with the risk of switching failure and train collision. Train derailments and collisions are themselves powerful events, given the mass and momentum of a fast-moving train, and of course collisions involving freight trains carry additional risks because of chemical spills and so forth. I think it's unlikely that any sort of portable bomb would do the sort of damage you have in mind, because even commuter train carriages are engineered with the possibility of a collision in mind. Although terrorist incidents of this kind have been very destructive where they've occurred, the fact is that the damage is relatively contained, and because it's an elevated risk environment (due to the possibility of accidents) there are robust safety and rescue protocols already in place.

As an example of the difference, consider the Oklahoma city truck bomb had explosive force equivalent to 5 kilotons of TNT, involved 13 barrels of explosive, and other materials, requiring a small box truck to transport. It did horrendous damage, but in terms of pure destructive force it wrecked about 1/3 of a 9-story building. The two plane impacts on the WTC, by contrast, caused the total collapse of two 80-story skyscrapers. There was lots of ancillary damage in both cases, but I stand by my arguments that it's harder to predict where an attack from the air will occur and that the destructive potential is typically larger in the case of a successful attack, because of the extra mass, speed, and height inputs.

The WTC incident spared many thousands of people due to the scheduling serendipity of being an hour or two before peak attendance.

Firstly there are sniffer dogs as well as bomb detection equipment around every airport I've been to. They are just deployed randomly which should be fine as a deterrence.

Secondly the reason commercial airlines are different from smaller planes and other bombing targets is because you can use one to kill tens of thousands of people (fly into large skyscrapers). You can't do that with a car bomb or crashing a small plane into a large one.

And the fact you have these incidents at all should tell you that airline security is important.

"Firstly there are sniffer dogs as well as bomb detection equipment around every airport I've been to."

I have yet to see them at an American airport. Maybe we have been flying to different places.

"Secondly the reason commercial airlines are different from smaller planes and other bombing targets is because you can use one to kill tens of thousands of people"

Tens of thousands? That's funny, because the largest terrorist attack on American soil involved airplanes and killed about 3000 people.

"You can't do that with a car bomb or crashing a small plane into a large one."

I was replying to someone who claimed that the job of the TSA is to prevent an airline bombing. Crashing a private jet into a commercial jet is a perfectly valid counterexample.

"And the fact you have these incidents at all should tell you that airline security is important."

We had one successful attack, which was extremely well planned and extremely well coordinated. We spend billions of dollars each year on the TSA. Billions of dollars because of an event so rare that we can only point to one occurrence.

Meanwhile, millions of people ride urban transit systems in large cities every day, and none of them are subjected to even the most rudimentary security. A subway train in New York has a capacity of over two thousand people, which is around how many would be on a packed rush hour train. A single terrorist could kill a large number of those people by detonating a powerful enough bomb while the train is going over a bridge or through a river tunnel (and probably in many other places). Yet despite that terrifying possibility, there are no body scanners, no bag X-rays, no shoe removal requirements, and no security lines at subway stations.

You can go ahead and cling to the idea that the TSA's airport security program is keeping us safe. The reality is that their program does almost nothing to promote safety or security; it is all the work that you do not see that is keeping you safe. The body scanners are not even a piece of the puzzle, they are a distraction meant to help people like you feel safe.

I've seen the dogs. Not sure what they were sniffing for - drugs, explosives, anything else - but they were there. Not every time, but it happened.

The ones I've seen to find something were sniffing for contraband imports to USA. Of course, elsewhere I've seen some sniffing for narcotics and explosives, but the only "live action" I've seen was when they did confiscate an apple from a passenger who just arrived in SFO. Not an Apple product, but an apple.

Agro produce regulations, probably. I had some produce confiscated once too. This is designed against various pests that could enter from overseas and from which local species have no protection, though I think it is futile because if they would get here they'd get here on cargo ship with thousand tons of apples, not in somebody's one apple.

Agreed. But I'd say the agro produce regulations, and sniffing the hand baggage of air passengers, are a bit similar thing for food hygiene as TSA checks are for air safety: an illusion that something is done.

    You can buy glass, you can get knives from restaurants.

I can't speak for US terminals but in many international ones. The glass you get isn't large enough to cause serious damage e.g. snowdomes and the knives in restaurants have deliberately dull blades. And cockpit doors whilst locked from the inside are routinely opened in order to provide food/drinks to the captain. So it's hardly a fool proof system.

But hey don't let me stop with your confused anti-TSA crusade.

That's funny, because the last time I went to an international airport I saw a duty-free shop with big glass bottles full of liquor. Hey, I must be confused about how much glass is needed to make a useful weapon. I have seen plenty of glass that a clever terrorist might steal from restaurants at small regional airports as well. As for knives, any knife that is sharp enough to cut a steak is sharp enough to be used as a weapon.

The thing is, I am not a terrorist. What I see as potential weapons are probably just the tip of the iceberg of things that can be turned into a weapon. Prisoners manage to make weapons out of all sorts of seemingly innocuous objects. What makes you think that the things I can identify as possible weapons are an evenly remotely exhaustive list? What makes you think that a terrorist could not find more weapons on the other side of security?

It is non trivial to smash a liquor bottle to produce a long shard strong enough to cause mass damage. And it has to be smashed without rousing attention amongst passengers. And even if you did cut someone it would take minutes to bleed to death.

And the knives rely on serration to cut through steak so are very dull.

And given that every country in the world has a TSA and abides by almost identical rules I would guess that there is a lot of people thinking about ways to make us safer. Why isn't the status quo the safest yet reasonable measures we have ?

"It is non trivial to smash a liquor bottle to produce a long shard strong enough to cause mass damage. And it has to be smashed without rousing attention amongst passengers."

I am pretty sure a terrorist would (a) practice smashing bottles until he can reliably create a weapon and (b) smash the bottle before boarding the plane, in an empty bathroom (I have been to international airports where no flights depart from an entire section during the night, yet passengers are free to wander around or sit in those sections), and just carry it on board because there are no security checks before boarding the plane.

"And the knives rely on serration to cut through steak so are very dull."

So you think a somewhat dull serrated edge could not be used as a weapon? Prisoners manage to use far less effective weapons to kill each other; why couldn't terrorists do it?

"given that every country in the world has a TSA"

What is your point? Everyone has a public display of their airport security? Do you think that it is impossible that everyone just wants their citizens to feel safe and that the point of a public security check is to do just that?

Have you actually seen a non-plastic knife in a secure area of an airport?