Machine designers have attempted to address privacy concerns by making it impossible for the person operating the machine to see the traveler being scanned, and by making sure that the images themselves are not stored or saved. However, a quick search for "full body scan" on Google Images will make it perfectly clear (pun intended) as to what the issues are.

For those edgy about the possibility of grainy gray full-frontal (and vaguely space alien) images of themselves floating around the Internet, the alternative is not much better. TSA protocol calls for pat-down searches for those who decline to go through the full body scanner; since 2004, the ACLU has been soliciting reports of pat-down abuses, ranging from inappropriate comments and touching to mandatory disrobing without proper privacy screens.

Is there an alternative to spending hundreds of millions of dollars on technology that might marginally increase passenger safety but most assuredly will decrease the privacy of those compelled to submit to a full body scan? Ironically, the answer might lie not in more invasive technology but less clothing.

Back in 2003, a small travel agency in Houston, Castaways Travel, created a stir by operating the first Naked Air (NSFW) flight from Miami, Fl to Cancun, Mexico on May 3, 2003. The one-off (or all-off, I guess) event ferried 90 intrepid passengers to and from to the Castaways Travel Nude Week held at the El Dorado and Hidden Beach Resorts in Cancun. This was not a true naked flight; pursuant to various uptight FAA regulations, the flight crew remained clothed throughout the flight and passengers could not disrobe until the plane reached cruising altitude (roll-your-own joke here). When the plane began descending into Cancun, the passengers were required to get dressed again. Five years later, a German travel agency called OssiUrlaub announced that it would book flights for nudists (in Germany, nudism is known as "Freikörperkultur" or "free body culture") to the Baltic island of Usedom. As in the U.S., passengers were require to remain clothed until take-off.

Maybe the nudists were on to something. Maybe true airline security only lies in stripping away our social conventions (and clothing), and relieving TSA of the challenge of checking both people and luggage. We already are required to voluntarily remove jackets and shoes before going through security; nearly complete confidence in the harmlessness of our fellow passengers is only a couple of clothing layers away (although as any drug mule will tell you, it's probably impossible to be absolutely confident that someone has not hidden a dangerous substance somewhere).

Can the concept of personal privacy be reconciled with the idea of naked air travel? Sure. As I discuss in American Privacy, the essence of privacy is choice -- the choice of what information about oneself to disclose, the choice of how that information will be used, and to whom it will be disseminated. For the founding fathers, privacy was embodied in the ability to choose one's religion and associates, to choose to refuse entry to government officials absent a particular warrant, and to choose to remain silent when charged with a crime.

Those constitutionally-protected choices are the foundation of liberty. (Not all of the founder's choices, admittedly, made it into the Constitution. Ben Franklin, for instance, was a big fan of "air baths" -- sitting naked for an hour or so by an open first-floor window in his London home.)

Wide-spread use of fully body scanning technology is designed to maintain the illusion of privacy while in reality stripping it away.

Obviously, air travelers consent to luggage and magnetometer searches in exchange for the promise of a safe flight, so some loss of privacy is inevitable (who hasn't wondered if TSA employees are amused or titillated by our wardrobes, our reading materials, our cosmetics and emolluments?). But backscatter x-ray images effectively destroy our control over very personal information about ourselves, information that we currently reveal to only a small number of people. As anyone who has followed the rise of the Internet is well aware, even marginally salacious images have a tendency to wander into the wild; because these images can be saved and disseminated, they inevitably will be. The only way to prevent that from happening is not to take them in the first place.

But, a prudish critic undoubtedly will reply, how is a fuzzy albeit explicit x-ray photo more invasive to personal privacy than spending an hour or two naked in the presence of dozens of strangers? The answer, I think, is two-fold: such an arrangement would maintain one's ability to control the disclosure of one's intimate personal appearance, while keeping everyone on an equal footing relative to each other and the government. Yes, various strangers would see information about us that is normally private, but the dissemination of that information would be limited to the equally naked people on the flight, for a limited period of time, and for a limited purpose -- a safe flight. Any such flight, of course, would be designated an absolute no-camera, no-imaging zone, with offenders permanently barred from ever flying again. Contrast that scenario to waking up one morning and finding out that your supposedly secure full-body scanner photo has been posted to www.XXXrays.com for the whole (clothed) world to see.

Admittedly, this idea is mostly facetious. There are probably fairly few people right now willing to fly the friendly sky totally starkers when a seemingly less invasive alternative exists, and the practical and social impediments to naked flights are obviously significant. But it's not totally out the question -- social mores and long-standing conventions can change quickly, when the pressure is great enough.

Witness, for instance, the changes in the centuries-old practice of communion in an era of the H1N1 virus and other high-profile diseases.

Our society already wears far less clothing, on average, than just a generation ago; how much modesty and privacy are we really maintaining anyway?

More seriously, the TSA's push to roll out more full-body scanners should spur us to ask two important questions that don't get discussed thoroughly enough: Should we continue to put faith in increasingly expensive technology to protect us, given the seemingly infinite ways in which competing technologies can be used to attack airline flights?

And is it in our best long-term interests to yield more and more control over our private information to the government in the equally futile pursuit of perfect security? As difficult as it is to say, the pervasive loss of control over our personal information is a far greater threat to our society as a whole than the suicidal impulses of a radicalized student.