The Transportation Security Administration's nude body scanners are controversial replacements for the metal detectors that have long prevented guns, watches and belt loops from making it onto airplanes unchecked. Are they effective? Will be we exposed to unhealthy levels of radiation? The TSA says yes and no to those questions, while a recent video from blogger Jonathan Corbett, who has sued the TSA for its use of the full body scanners, disputes the scanners' effectiveness.
In the video, Corbett claims that the body scanners can be tricked into missing metallic objects through a ridiculously simple technique. Scanned bodies appear as light negatives against a dark backdrop in the system, and because metal objects show up black, Corbett says any metal placed away from the body is completely invisible to the scanners.
If Corbett is correct, the government is spending billions on scanners that are less effective at detecting metal objects than existing metal detectors. "It can't possibly be that easy to beat the TSA's billion dollar fleet of nude body scanners, right?" he asks. But is his test legitimate?
Corbett clearly shows himself traveling through airport security without his small metal case alerting the TSA. One Reddit commenter, who claims to work with the same full body scanners, provides his own response:
His explanation of how metal objects appear dark and organic material appears bright is correct. However, the background is not black but a dark grey color. The images in the video (particularly the one on the left) look like they've had their levels adjusted to exaggerate this. Metals shows up almost completely black against a dark grey background. You can definitely see them.
The issue mentioned in the video was a weakness of the single scanner systems in the past. The more modern double scanner units in US airports such as the Rapiscan Secure 1000 SP don't suffer so much from this problem. Basically, the second scanner unit causes the background to be dark grey rather than black since it provides a small amount of backscatter. That makes metallic objects visible on the side of the body.
He goes on to explain that the IEEE N42.47-2010 "American National Standard for Measuring the Imaging Performance of X-ray and Gamma-ray Systems for Security Screening of Humans" contains a test for "materials detection off body," and claims the Rapiscan Secure 1000 Single Pose passes that test.
Rapiscan's Secure 1000MP, a mobile deployment version of the 1000 Series, does claim to support off-body detection of objects.
This leaves us with a few possible explanations for Corbett's video.
- Corbett's video is legitimate, and the body scanners did not spot his metallic object as claimed.
- The scanner worked, but the TSA agents missed the object due to negligence.
- The scanner worked, but the TSA agents deemed that the object was not a threat.
- Corbett's video is misleading. He misrepresented the darkness of the background scanners.
The final explanation doesn't account for Corbett apparently carrying a metal object past security; it's entirely possible TSA ineptitude played a part as well. Regardless, it's too early to pass off billions of dollars in spending as completely wasted, even if the TSA has a reputation for poor security practices.