[robobenjie]

I agree with most of the points in this article, but saying that all people who forge boarding passes will use latex gloves seems false.

From my point of view the point of multiple screenings is to increase the difficulty and complexity of pulling off a particular attack. Sure, individually you can think of a way to counter each one, but as you add constraints you reduce the pool of people willing and able to pull it off. (So now you need a person who wants to cause terror, who is willing to blow themselves up, who can forge simple documents, who remembered to wear latex gloves, who can act cool enough to avoid extra screenings when walking past guards with machine guns, etc, etc, etc). Sure some eliminate more than others, but you multiply enough .95s together and you get a small number.

[johnthedebs]

You seem to be looking at this the wrong way. Instead, consider that once a person has decided they want to cause terror so much that they are willing to blow themselves up, they'll go to great lengths to make sure their one opportunity to do so succeeds.

These chances of passing these screenings aren't independent. They aren't just die rolls where a terrorist needs to roll 6 five times in a row for their plot to succeed. If they can improve their chances on one screening they can and will improve their chances on the rest (which was the point he was trying to make).

Now consider how much time and money is spent for each additional screening that's put into place, both for those putting it in place and the millions that have to jump through all the extra hoops each day to travel. Worth it?

[dalke]

It's more "all people who forge boarding passes with the intent of using the plane as part of a terroristic plot will use latex gloves if they also have a bomb."

The point was that multiple layers are only useful if they test different thing. I'm more inclined to believe that those two layers are "tantamount to performing the same test twice" because they can both be done before the fact, and planned for.

The problem about multiplying enough 0.95s together is the number of false positives that occur. The article mentions one, where an air marshal killed a deranged passenger in Miami. That's an extreme case. Hidden is the, what, 5 minutes needed for screening * 700 million passengers per year giving over 6,000 extra person-years wasted waiting on security every year.

[nlawalker]

The thing is, it's not a bunch of .95s. It's a .00000001 and a bunch of .9999999s. If a person wants to cause terror and is willing to blow themselves up, they're probably already very resolved and willing to do virtually anything else necessary to bypass the security measures you mention and any others.

[WettowelReactor]

Or if all else fails they can blow themselves up at the security checkpoint, or on a train, or on a bus, or metro, or .... Really once a person has decided to blow themselves up their options for committing terrorism are exceedingly large. Luckily this group of people is surprisingly small but or reactions to to the risks are way overboard.