John Pistole, head of the Transportation Security Administration, says the agency's new backscatter X-ray scanners "can detect both metallic items and nonmetallic substances such as powders, liquids, and gels that can be used in explosive devices." Just one problem: The high-tech machines don't work if the bombs are shaped like pancakes.
According to The Journal of Transportation Security, in an article posted online in November, it is "very likely" that a pancake-shaped pouch filled with powder and taped to an individual's gut would escape notice by a screener viewing scanner images. Such a pouch would blend in with the scanned body in the image created by the scanner and "be easily confused with normal anatomy." The authors of the study note that if a dangerous amount of the high-explosive PETN powder were affixed to the body in this way, it would be easily detected in a traditional pat-down, thanks to its bulk. But if it went through the new scanners, it would be "virtually invisible."
Nor are explosives the only potentially dangerous items the scans might fail to detect. According to the report, "an object such as a wire or a box- cutter blade, taped to the side of the body, or even a small gun in the same location, will be invisible."