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Will searches ever catch terrorists?

Transportation Security Administration screener Marlon Tejada, left, watches as Randy Parsons, the TSA's acting federal security director goes through a full-body X-ray scan today at Los Angeles International Airport.
Transportation Security Administration screener Marlon Tejada, left, watches as Randy Parsons, the TSA's acting federal security director goes through a full-body X-ray scan today at Los Angeles International Airport.Damian Dovarganes / AP

Doing highly publicized, invasive screening on a random basis will probably never catch a terrorist … but that’s not the point, experts say.

The nationwide phase-in of full-body airport scanners that work like Superman's X-ray vision, along with pat-downs that include checking your private parts, are the latest moves in an arms race between would-be attackers and the authorities. This time around, the escalation is a delayed response to the "underwear bomber" airliner attack that was attempted last Christmas -- but which failed because the bomber couldn't detonate his explosives-laden briefs.

Unfortunately, it's an arms race that has caught the traveling public in the crossfire. The pat-downs and body scans have sparked a wave of outrage that could break with full force on Wednesday, when fliers are being asked to "opt out" of the body scans and undergo the intrusive pat-downs instead. The result could be a massive jam-up of airport security on the year's busiest travel day.

Responding to the outcry, John Pistole, the head of the embattled Transportation Security Administration, told NBC's TODAY show that only "a very small percent" of air travelers have had pat-downs. Which raises a statistical question: If only a small percent of passengers are being checked, doesn't that mean there's a large chance that a terrorist would slip through?

The TSA doesn't talk about the details of its security policies, which is arguably behind some of the agency's public-perception problems. But in a paper that was published in the online journal First Monday back in 2003, researchers at the Massachusetts Institute of Technology said the typical airport puts 2 to 8 percent of its passengers through extra screening. Today, NBC News' Tom Costello quoted the TSA as saying that less than 3 percent of passengers are being selected for pat-downs:

Those figures might seem to imply that a terrorist would have more than a 90 percent chance of getting through security undetected, if he or she were using a method of attack that could not be detected through normal screening.

So why bother? Well, those calculations don't consider the deterrent effect of random screening.

Brian Michael Jenkins, a senior adviser at the RAND Corp. and a former member of the White House Commission on Aviation Safety and Security, noted that the rate of attempted terrorist hijackings and sabotage has declined dramatically since the 1970s, even through the post-9/11 era. "We can claim, No. 1, that the security measures do represent a deterrent," he told me. "And we can also claim that the security measures have increased the operational difficulties for our adversaries, to the point that their devices are increasingly unreliable." Underwear bomber Umar Farouk Abdulmutallab as well as the shoe bomber Richard Reid have demonstrated that last point.

At the same time, Jenkins acknowledged that the escalation of the arms race was reaching the point at which bombs could conceivably be undetectable except through the most intrusive types of searches -- which is where we're heading today.

"We have to accept the possibility that sometimes our adversaries may succeed," Jenkins said. "That dynamic notion of security is hard for people to accept. We are in the risk business, not the prevention business."

How intrusive should searches be?

The past few days have brought a succession of horror stories ... about a breast-cancer patient who was forced to show her prosthetic breast, for example, or a traveler whose urine collection bag spilled during a search. But when properly done, the searches should be no more intrusive that "what one would get from an airport in Germany or France," Jenkins said.

Douglas R. Laird, a former security director for Northwest Airlines who now has his own Nevada-based consulting firm, echoed Jenkins' view that some of the controversy over "touching your junk" was unjustified: "If you're going to do a physical pat-down, then you should do it correctly, and the only way to do it correctly is to be invasive," he told me. "If you can't touch the privates, that's where the terrorists are going to put the stuff."

So what's next? Body-cavity searches?

Actually, Jenkins, Laird and many other experts on aviation security favor switching over to an entirely different approach. "We cannot have our security system rely exclusively on a search for objects," Jenkins said. "We are going to have to move toward a more discerning system that also measures risks according to the person."

Aviation authorities have already been experimenting with programs for registered travelers -- in which frequent fliers give up some information about themselves and, in return, are allowed to take a fast track through the airport security lines. "There won't be an absence of security for such people, but we'll move toward a pre-9/11 screening regime, or a somewhat lighter version," Jenkins said.

On the other side of the spectrum, some fliers might be singled out for more intensive screening -- based on the behavioral cues they're sending out (for example, sweating or looking around while being questioned) or on their flight history (for example, showing up on the records as having taken a trip to Yemen). "I'm not against profiling, but it has to be done using the right parameters," Laird said. "I'm against doing it for the wrong reasons. It shouldn't be based on race or ethnic origin."

Jenkins acknowledged that the idea of separating fliers into different categories would probably rub lots of passengers the wrong way ... just as some passengers are saying today that they're being rubbed in the wrong way.

"To me, the issue is not this fake controversy that's going on now," he said. "That is a distraction from a more fundamental question -- which is, given increasing passenger loads and increased security requirements, and a determined and creative foe, how do we best manage this risk and not cause the system to break down?"

Here's how risk-communication consultant David Ropeik, author of the book "How Risky Is It, Really?" (and a former contributor), put it today in a posting on the Psychology Today blog:

"Most risks involve tradeoffs of some sort. In this case it's a risk-risk tradeoff, between getting blown up on the one hand and feeling coerced into having your privacy invaded while being exposed to minute doses of radiation on the other. If Risk 1 -- getting blown up -- doesn't feel like a real possibility, you're less willing to live with Risk 2. If the negative qualities of Risk 2 -- radiation, coercion, invasion of privacy -- feel bigger, Risk 2 will matter more than Risk 1.

"It all adds up to a kind of a silly way to think about how to protect ourselves from the constant and real threat of bad guys and bombs on planes. But then, risk perception isn't just about thinking. It's about feeling too. And in this case, what feels right ... resisting a procedure that could keep us safer ... may actually make things worse."

I realize this perspective may be completely different from what you've been hearing over the past few days. I'd love to hear your perspective as well. Please feel free to sound off in the comment section below.

More about the airport security controversy:

For more about Jenkins' perspective on aviation security, check out this article on Scientific American's website.

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