The US Transport Security Administration (TSA) has celebrated the successful trial of 'see through clothes' scanners by ordering 30 more of the millimeter wave devices for Los Angeles and JFK International airports this spring.

The scanners, which produce a whole, naked, body image, have been in use at Phoenix Sky Harbor Airport since October last year, following an earlier deployment there of backscatter whole body scanners.

Neither flavour of scanner seems to have massively outraged the Phoenix air travelling public, and the TSA claims a 79 per cent acceptance rate for backscatter, which uses low intensity x-ray technology. In Phoenix, however, backscatter was offered as a voluntary alternative to a pat-down to passengers selected for secondary screening - i.e., it wasn't an option offered to all passengers, just for the ones security was already suspicious of, or who thought security was already suspicious of them. 'Don't make trouble' could have a serious effect on a scanner's acceptance rate. For the more recent millimeter wave deployment, the TSA claims 90 per cent of passengers preferred the scanner to the pat-down.

LAX and JFK passengers won't be getting quite the same treatment. The JFK trial will operate in the same way as the Phoenix one, while at LAX passengers will be selected at random, and according to the TSA, those who decline the offer of a virtual strip-search will be offered "alternative screening measures." Whether by this the TSA means a pat down, an aggressive pat down by a lascivious goon, or something even more "alternative" involving hosepipes, is not clear.

The LAX pilot, says the TSA, will allow it "to examine millimeter wave's operational capability, throughput, training, ease of use and privacy perceptions by the traveling public." Privacy is certainly an issue. Millimeter wave scanner images aren't exactly what you'd call porn, but they produce a fair rendering of the human body underneath the clothes, revealing non-metallic but troubling items that might be concealed by your average drug smuggler or terrorist. The TSA seems not as yet to have come up with a privacy FAQ specific to these scanners, but the backscatter one covers similar territory, less graphically. Does that woman have two navels, or is it just us? The TSA's "actual image" graphics, in any event, seem mysteriously less detailed than the ones used in conjunction with its failed attempt to introduce backscatter at Orlando airport in 2002.

The viewing set up for the new scanners is intended to "ensure privacy." Images are viewed by officers at a "remote location"; so you can't hear them laughing, and as they can't see your actual body they're unable to recognise you (later, say, in some bar) and laugh again then. Unless your shape is seriously distinctive. Images are deleted after they've been viewed, we are told.

At the time of the announcement of the Phoenix pilot the TSA committed to buying eight of the scanners to cover this and the JFK and LAX rollouts. But with the number now up to 30 the intent is clearly to deploy them generally, no arguments.

The scanners being used are ProVisions from L3 Communications, which claims scans can be generated in "as little as 10 seconds" and have "potential peak throughput levels of over 400 people an hour". Multilane configurations are available, which is possibly how the maths of those claims work. ®