[NOTE: since I wrote this article the BBC report has been amended; not all passengers will be forced through the scanners... but there is still the threat that this is next step]
Intelligent travellers are already aware that much airport security is just window-dressing. It will deter a half-hearted attacker, and make terrorism a bit more of a challenge, but security scanning on its own won't prevent any determined attempts. Its main function is to reassure passengers that something is being done.
Since Christmas, in a knee-jerk response to the 'underpants bomber,' authorities have decided that something more must be seen to be done. So your naked body will be open for inspection. (Some reports, in fact, observe that the body-scanners would actually not have detected the underpants explosives.)
So how will it work? Men in a small room will examine your x-ray. They will view your genitalia, breasts, underwear, any medical support items you are wearing, perhaps any implants you have. Some will come from cultures where the sight of mere female hair is taboo - yet they will be viewing your entire naked body. Some will probably laugh, point and maybe make prints of the image. No-one can believe assurances that this won't happen. We all know that shop security guards make compilations of CCTV shots down women's tops and so on.
The embarrassment of airports over whether children should go through them (knee-jerk paedophile alert) hardly allays fears over whether body scans can be recorded, or used for titillation.
Any 'padding' or bulk will presumably cause an alarm - this is, after all, the supposed purpose of the scanning. So, seriously, are the security guards going to pull aside all little old ladies wearing incontinence pads, or menstruating women wearing sanitary pads? Are they going to strip all these passengers and rip up the sanitary pad to check it doesn't contain anything untoward? Do airport staff have the stomach, or the manpower, or the cruelty to do this? Very unlikely - and it would be outrageous were they to try. They will simply resort, as now, to unofficial profiling. They'll look at the women and will generally make the assumption that these women are innocent and choose to let them through. Which has made the body scanning completely pointless; it has merely humiliated passengers to no purpose.
It is obvious to everyone that there are still ways to smuggle small amounts of explosives through these scanners. They only scan clothing, and don't penetrate inside the body.
So the machines don't make us safer, they just take away our modesty and humiliate us, in the name of PR. In order to travel by air, you will be offering your naked body and most intimate secrets up to strangers. I have accepted the lack of rights awarded to travellers up to now. Metal detectors, liquid limits, passport scanning to record my movements, bag searches. Even pat-downs - at least these are carried out in your presence, by same-sex staff, with discretion. But universal 'naked scanning' really seems an intrusive step too far.
Profiling of passengers would be much more effective, and it certainly already happens, up to point. A braver and more consistent approach to the policy, combined with selective 'deep scanning' would be more logical than the current emphasis on equality and universal mistrust. At the end of the day, flying, like other activities, means taking a risk. However much the airlines and airports try to inconvenience us, we will still be taking a risk. As travellers we should support rational and realistic attempts to protect us, without having our journeys made unbearable by largely pointless security measures.
Articles from the last time this issue featured in the press:
Airport full-body scanners 'break laws on privacy' (Sunday Times, subscription)
New scanners break child porn laws (Guardian)
Are planned airport scanners just a scam? (Independent)
Why we must profile airline passengers by the editor of Aviation Security International
A couple more points: do we actually know of any terrorism attempts which have been prevented by airport security scanning? And despite human rights organisations' insistence on 'equal treatment', could profiling have helped in spotting past bombers?