A year after her exposé "Inside Job: My Life as an Airport Screener," Barbara S. Peterson reports on the U.S. government's latest investigation into airport security

One of my most vivid memories from the two months I spent working as a Transportation Security Administration (TSA) screener a little over a year ago is of the feeling that we were constantly being watched. We knew that anonymous TSA testers were out there trying to trip us up: The agency conducts upwards of 2,000 such tests a day around the country, and the results can help determine who gets promoted or, just as frequently, who gets put on probation. We also knew that the Department of Homeland Security did its own sleuthing. One day, when I gave a too cursory going-over to a passenger in a wheelchair, my supervisor scolded me by saying: "They hid a gun in a wheelchair once, and we didn't catch it!" The usual response to these failures is to send screeners for more training.

But there's another test whose results have generated far greater attention: Congress's own undercover investigation, in which, for the second time in two years, bomb components were successfully smuggled past security screeners in a test of some 20 unnamed U.S. airports. The resulting Government Accountability Office (GAO) study, released late last year, drew the expected cries of outrage from legislators and the public, and inevitably led to serious questions about the efficacy of the nation's aviation security system. "The TSA promised to plug these holes…but they are not succeeding. That's an embarrassing and dangerous record," said Congressman Henry Waxman last November at a hearing of the House Committee on Oversight and Government Reform, which he chairs. The GAO's latest foray was designed to learn if the TSA's year-old restrictions on liquids were working. Its downbeat assessment: A would-be attacker could go on the Internet and, for less than $150, purchase some perfectly innocent substances that could be carried through security separately and later reassembled as an incendiary device powerful enough to take down an aircraft.

To those intimate with the checkpoints, the finding is no surprise: Testers are still breaching the system, mainly because most of the tools that screeners rely on to spot dangerous items haven't changed in years. In fact, one way the GAO gumshoes got liquid explosives past the metal magnetometer at the checkpoint was to hide them in their clothes. Liquids, of course, can pass unnoticed if they are in non-metallic containers, and a thorough pat-down is usually done only if a passenger sets off an alarm or is selected for further screening.

The testers also brought plastic explosives through in their bags, exploiting the limitations of X-ray machines in spotting them; similarly, detonators can be disguised as benign objects such as cell phones and radios.

"We need to dramatically improve the technology," TSA Director Kip Hawley told Congress. But how that will be done on the TSA's tight budget was not addressed by either the agency or the legislators who control the purse strings. Last year, Congress gave the TSA some $100 million for new technology, but it will cost far more to replace all the antiquated equipment still in use at the roughly 2,500 checkpoint lanes in the United States, which process 2 million people each day. Nationwide, TSA screeners at security checkpoints view some 10 million grainy X-ray images daily, only the smallest fraction of which contain anything that could prove dangerous to an aircraft. The X-ray machine I was trained on was typical: It showed only two-dimensional views that were very hard to read if a bag was densely packed.