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Schneier on TSA

I've lost a lost of pocketknives to TSA, so I was particularly biased to like the way Bruce Schneier framed TSA security.

Schneier on Security: Sneaking Items Aboard Aircraft

Security systems fail in one of two ways. They can fail to stop the bad guy, and they can mistakenly stop the good guy. The TSA likes to measure its success by looking at the forbidden items they have prevented from being carried onto aircraft, but that's wrong. Every time the TSA takes a pocketknife from an innocent person, that's a security failure. It's a false alarm. The system has prevented access where no prevention was required.

Comments (4)


I think I'd rate those as (acceptable) false positives rather than failures. They are not, however, successes. Successes are prevented incidents -- something that can be obnoxiously hard to quantify. After all, there was at least one success of that type of September 11...probably (that is, a team that didn't get on their target plane).

It's like any prevention program -- you can measure its success over time by the decrease in incidents, but you can't easily point to specific instances of prevention (e.g. "Because of our new health food program, Joe didn't get that cancer he was otherwise destined to have.")


I didn't include the full excerpt, but the article is relation to a PA Supreme Court judge, who now faces fines for his determination to get a pocketknife through.

A modified version of the question is (in response to your comment), "Is it still an acceptable false positive when coupled with a fine and/or criminal charges?" One might argue that the fine/charges are necessary in order to prevent people from attempting to circumvent the screening, but the problem is that the person hasn't done anything "wrong." The seizing of pocketknives/nail clippers/lighters/tools and other items is justified under the pretense that they might be used by terrorists, but if you punish someone who is not a terrorist, then that is in fact a failure of your security system -- they are being punished as an example to others.


I'd say as long as the regulation is advertised sufficiently, and people are given a way to opt out of being in trouble whenever possible, it's still acceptable. After all, I've accidentally brought my not-very-innocuous Benchmade folding knife into airport security twice, and was able to walk out. Now, I'm certain many such knives would be siezed under these circumstances, and that's not an effective implementation of policy, nor is a fine or jail time immediately. A good implementation might be to take the person for an additional search, then offer them the possibility of storing or otherwise dealing with the offending item (up to and including the option of not taking the flight).

Many items are seized, banned or regulated, sometimes on a site-specific basis, because they might be used for bad things. This does represent a failure of perfect security, in that ideally, you'd identify and stop threatening individuals. The fundamental problem with that is situations where failure of the ideal method lets an offender cause critical harm. Then I think it makes sense to go with the less ideal method of setting boundaries and regulating them.

Of course, a good secondary question here is "Will anyone, ever again, let someone take over an airplane because that someone is armed with a box cutter?" Common wisdom says the answer is "no," but I'd actually like to see that simulated and tested somehow.

(I'd think the new terrorist plan would be to identify the air marshal and seize his or her gun...)


According to TSA regulations, "If permitted by the screener or Law Enforcement Officer, you may be allowed to: consult with the airlines for possible assistance in placing the prohibited item in checked baggage; withdraw with the item from the screening checkpoint at that time; make other arrangements for the item, such as taking it to your car; or, voluntarily abandon the item."

The "If permitted by the screener" clause is notable from personal experience. When they took my C02 cartridge, I was not permitted to exit security with it and dispose of it. They insisted on taking my identification and the item and filling out a hazmat report. Perhaps the more insulting aspect was that I felt that they chose this course of action because one of the agents had never filled out a hazmat form before, and he was excited at the opportunity to do so.

I would like your secondary question tested as well, because I see the current philosophy behind the screening as misguided. The threat model is that you are trying to prevent terrorists from taking control of a plane. Reinforcing cockpit doors was a good step; I would like to see more money invested in policies and technologies to make cockpits inpenetrable. Instead, we invest money in policies (screening) that are hit-or-miss, but are theatric in nature. Until Leatherman figures out a way to fit a cutting torch in their next lineup, I personally don't worry about knives, tools, or lighters making it onto the plane anymore than I worry about those items when I'm not on a plane.


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This page contains a single entry from kwc blog posted on February 28, 2005 7:26 PM.

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