…while offering no improvement whatsoever in security. I mean, of course, the Future Attribute Screening Technology, or FAST, that the DHS is testing to try and spot people who intend to commit acts of terrorism. How do I know that it won’t improve security? Just do the math. According to the article, in laboratory tests the technology was correct in discerning intentions 70% of the time. Let’s assume that they improve that with a little tweaking. In fact, I’ll assume that they can make it so good that it’s correct 90% of the time.
So they can catch 90% of the terrorists. Great! But how many terrorists is that? Since the implementation of new security after 9/11, the average number of terrorists per year that have attempted to board airlines at U.S. airports (the only ones where DHS has jurisdiction) is… zero. No terrorists have tried to get on to planes. Therefore, no terrorists were stopped by airline security. Were they deterred by the added security that the TSA has already deployed? It’s possible, but there weren’t any attacks in the ten years prior to 9/11 either.
But just for the sake of argument, suppose there was one person planning to attack an airliner. According to the United States Bureau of Transportation Statistics, approximately 786.7 million passengers traveled by air in the United States in 2010. Of these, the FAST machine would identify 78,670,000 people as possible terrorists, if it’s correct 90% of the time. That’s almost 80 million people, 1 of whom is a terrorist in this scenario. Can the TSA realistically stop 80 million people from flying? Of course not. So how do they determine which 1 of the 78,670,000 positive results is really the terrorist, when they don’t actually know that there is a terrorist in the group at all? And even if they do, absurdly, stop everybody who fails the test from getting on the plane, there’s still a 1 in 10 chance the actual terrorist got through.
And, of course, nearly every one of those 78,670,000 will try to fly again the next day. The TSA obviously can’t put these people on the no-fly list, or very soon nobody will be allowed to fly at all. And every time the terrorist tries again, there’s another 1 in 10 chance that he’ll succeed and get on the plane.
The best that FAST could do, even assuming an extremely unlikely 90% success rate, is delay a terrorist attack by a few days. This at the cost of harassing tens of millions of innocent people, disrupting business travel, and largely ending airline travel for tourists (a family of 4 has only a 66% chance of being allowed to board the plane together).