Summary: Pursuant to a congressional request, GAO provided updated information on commercially available advanced explosives detection devices that can be used to screen checked baggage, carry-on items, passengers, cargo, and mail.
GAO noted that: (1) a number of advanced explosives detection devices are commercially available that can increase the probability of detecting concealed explosives; (2) however, all of them have performance limitations; (3) for example, some devices can detect only certain explosives, while others have slow baggage processing rates; (4) others rely almost entirely on the skills of the operators rather than on automatic alarms; (5) despite their various performance limitations, these devices can improve security while providing operational performance information that can be useful in improving the current or next generation of devices; (6) the predominant technologies available for detecting the presence of explosive materials are various types of X-rays, chemical trace detection, and electromagnetic analyses; (7) these technologies are incorporated into a variety of devices used to examine checked baggage, carry-on items and electronic equipment, passengers, cargo, and mail; (8) generally, X-ray devices operate by passing X-rays through screened items and projecting an image of the contents being examined on a monitor; (9) potentially explosive materials are identified by their density, average atomic number, and appearance; (10) the detection capabilities of these devices vary in terms of how the X-ray systems function; (11) the devices also vary in terms of whether the presence of potential explosives is signaled by an automatic alarm or is manually identified by an operator; (12) the Federal Aviation Administration has certified one X-ray device for screening checked bags, the CTX 5000 SP, as meeting its performance standard; (13) chemical trace devices rely on the identification of the presence of explosive vapors and residues that are associated with explosive materials; (14) these devices are also known as "sniffers" or "trace detectors"; (15) samples are obtained through techniques such as using a wipe or a vacuum, examining a document or some other item that has been handled by the passenger, or sampling air gathered at walk-through portals; (16) for each technique, the sample is analyzed by a device to detect explosives; (17) most of these devices include an automatic alarm when explosive materials are found; (18) electromagnetic devices generally use radio frequency pulses that probe baggage or other items to elicit unique responses that would be associated with explosive materials; and (19) these devices generally include an automatic alarm if the presence of explosives is detected.
