My time as a screener also highlighted the urgent need to reduce the number of passengers deemed a threat. For years, the TSA has been promising to come up with a more intelligent way to identify those who merit secondary screening—but the no-fly and watch lists remain scandalously out of date. (I personally encountered fliers who have the same very common name as someone on the watch list and who are selected for additional screening every time they fly.) The private-sector registered-traveler program that was expanded late last year may be a start. And since it's voluntary, it has excited less outrage from civil rights groups than the more sweeping proposal to pre-screen all fliers. In charging people a hundred dollars for the right to submit to a background check that allows them to speed through security with a biometric I.D., the program is rightfully criticized as elitist.

Simply creating this privileged class of traveler, however, might fire up the rest of the flying public: As they struggle out of their shoes and coats, they would see that the technology exists to make the process far more efficient but that the government is not willing to pay for it. Maybe then the blame can start to shift from the screeners to Congress, where it belongs.

As technology begins to solve the current problems, just how essential to aviation security will TSA personnel ultimately be? Very—just not as much at the checkpoint as they are today. Schneier and fellow critics make the eminently sensible argument that if we were to divert just a small fraction of the TSA's four-billion-dollar annual budget into intelligence gathering and basic gumshoe work (as the Israelis and many Western European nations do), we'd be far better off.

The good news is that it's already beginning to happen. In late January, I learned that one of my supervisors, a former police officer, had been chosen to be part of a crack unit of newly minted "behavior-detection officers," who will patrol airport concourses and lobbies to look for suspicious people rather than suspicious things. This, in essence, is the kind of old-fashioned detective work that snared the would-be London bombers last August. It works. I hope it will soon be part of a smarter aviation security system for U.S. air travelers, who deserve it every bit as much.

Ways to Speed Through Security Checkpoints

DON'T tell a screener that you are about to miss your flight (it won't win you any sympathy and could even arouse suspicion).

DON'T wear clothing with metallic objects such as buckles.

DON'T wear lots of jewelry or hairpins that can't be easily removed.

DON'T say you "forgot" you have liquids in your bag.

DON'T try to jam everything into one bin in a misguided effort to be helpful—it's much harder to screen.

DON'T accuse screeners of theft: Once you're certain an item is missing, speak to a supervisor.

DON'T tell screeners "it only comes in this size" or "it's almost empty" when asked to surrender containers of liquid larger than three ounces.

DON'T tell them how much you spent on the toiletries—it won't make any difference if they're the wrong size.

DON'T block traffic by repacking your belongings on the conveyor belt.

DO wear easily removable shoes.

DO keep your boarding pass in hand.

DO take the plastic bag holding liquids out of your carry-on before putting it through the X-ray machine.

DO lay your bag on its side (the upright position is much harder to "read" and may trigger a rescreening).

DO put items through the X-ray machine only when you are ready to walk through the metal detector. This minimizes the time you're separated from your belongings.

DO make sure that you have all items before you leave the checkpoint.