Monday, January 11, 2010

Bombs versus Bareness: The Choice for Airline Safety?

After Abdul Farouk Abdulmutallab tried to explode his underwear on a Christmas-day flight from Holland to the U. S. last year, a lot of people got a lot more interested in airport security, and understandably so. In particular, more attention has been focused on the so-called "full-body scanners" now in use at a few U. S. airports. The Transportation Security Administration has ordered 150 more and has money for 300 of these devices. According to a report in the Washington Post, if the Dutch airport where Abdulmutallab boarded his plane had been using such a scanner, they would very likely have caught him. But there are privacy concerns about these devices.

By now you have probably seen sample images from the machines on TV: they look like what you might get if you took one of those little wooden life-modeling dolls that artists use to get the basics of the human figure down, and put it on a copier-machine screen and scanned it. The level of detail is low; objects smaller than about half an inch in diameter are at the edge of the system's resolution. And the faces and certain other personal areas have been obscured by software so you see just a uniform gray blur. Nevertheless, the machines can't do their intended job unless they present the basic body outline minus clothing, and depending on who you are and what shape you're in, even that amount of detail may be too much for some people.

We are told that the folks looking at these pictures will not be able to see the real humans whose images they're checking—the inspectors will be in another part of the building. I suppose that helps—if anybody snickers, at least you won't be able to see them do it.

The right to privacy is a fairly modern one in some ways, being the basis of the 1973 Roe v. Wade decision legalizing abortion in the U. S. But as in so many situations where technology outpaces the legal system, the right not to have people look at your naked body by means of technology is not well defined. There are peeping-tom laws: if some creep in your apartment complex installs a hidden video camera in your shower and gets caught, there are ways to prosecute him. But this is a different situation, since it is the police who are doing the snooping, and for a good purpose: to keep bombs off planes.

As I may have related elsewhere, I was involved in an experimental program way back in the early 1990s to develop just such a contraband-detection system using millimeter waves, a type of microwave that is naturally emitted by the human body. Somewhere I have millimeter-wave pictures of myself with and without some Play-Doh taped underneath a windbreaker. There were two problems with the technology at the time. One was, a full-body scan (actually only the upper half, now I think about it) took 45 minutes. And the level of detail was sufficiently good that the company I was working for wasn't able to market the thing successfully, partly out of privacy concerns. As I recall, the images weren't any more detailed than what we've seen in the papers lately, but attitudes about what constitutes too much detail have changed a good bit since then. And we've had things like the Sept. 11, 2001 World Trade Center bombings happen.

I don't see much in the way of organized opposition to these devices, however the privacy issue is handled. The alternative that people are being given at airports is to submit to a pat-down, which is a privacy intrusion of a different kind. If the new technology was foolproof, it might be more justifiable, but neither the full-body scan nor a patdown will detect the ultimate in suicide bombing techniques: a person with a bomb inside their body that can be set off by a cell phone. If they start checking for those things, I think I'll just take the train.


For the first year or two after I began writing this blog in 2008, a number of readers sent in comments, which is a fairly simple thing to do. If you already have an identity on this website, you can post comments right away and they show up immediately without my intervention. If you post as "anonymous" I get an email from the system allowing me to exercise my judgment as to whether to post the comment or not. There are only two kinds of comments I won't post: ones which in my judgment are scandalous or libelous (I get very few of those), or spam. Unfortunately, in the last few months about 90% of the comments I've been getting are spam: either innocuous-sounding general things like "Oh gee I really like your blog" followed by a URL that is clearly advertising, or else a comment entirely in Chinese. Although I wish I could read Chinese, I can't, and these go in the bit trash along with the spam. In the meantime, the "real" comments have dwindled to almost zero.

So here is my request: if you read this blog at all, either occasionally or regularly, would you please email me directly (not comment) at, subject line "Your Blog" and let me know what you think about it? All comments, good or bad, will be welcome, because I'm operating right now in what engineers call an "open-loop" situation with no feedback, and that's generally not a good state for a system to be in. I promise to read all your responses and summarize them in a blog soon. Thank you, and have a happy 2010.

Sources: The Washington Post carried an article on full-body scanners and their planned deployment at There is information about how the technology works at And the article in which I showed off the capability of a 1993-era millimeter-wave contraband detection system is “Contraband detection through clothing by means of millimeter-wave imaging,” by G. R. Huguenin, C.-T. Hsieh, J. E. Kapitsky, E. L. Moore, K. D. Stephan, and A. S. Vickery, SPIE Proc. 1942 Underground and Obscured Object Imaging and Detection, Orlando, FL, pp. 117-128, 15-16 April 1993.

1 comment:

  1. I know I'm not following direction, and should be emailing, but I do read your blog on a regular basis, and think it's quite good. On the post at hand: Don't think railtravel is a secure panacea. Spain, '05. The relative laxity of security at train stations leaves me amazed that such attacks have not been attempted in the US (Amtrak or the various big city rail systems, especially on the East Coast.)

    That, along with the miles of track, unguarded track, makes me uneasy. Sad fact is there are no failsafe guarantees.