Because 9/11 was a breach in airport security, air travel was supposed to be fixed first. Americans are certainly paying to fix it, in time and money. The $3.4 billion spent on airport and airline security in 2005 represents a more than tenfold increase over 2000. The Transportation Security Administration (TSA) has federalized airport screeners and upgraded their training and vigilance. Cockpit doors are locked and hardened, and domestic pilots are allowed to carry guns. Flight attendants are instructed in how to identify suspicious passengers, restrain those who are dangerous and handle explosive materials. Expensive “explosive detection systems” have been installed in airports to screen all checked baggage.

So compared to securing borders, ports and chemical facilities, where congressional oversight is spotty and politics frequently trumps security, aviation has seemed a model of terrorism prevention.

But is it? Since 2002, more than 100 media reports have documented security breaches involving knives, explosives and even handguns. In March, NBC News revealed that government investigators smuggled materials for homemade bombs through security at all 21 airports they tested–materials similar to those involved in the London plot. But nothing was done until last week, just as shoes were not removed at airport security until Richard Reid tried to explode a shoe bomb in 2002. “We keep chasing yesterday’s story,” says Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia and author of a new book, “Americans at Risk.” “The terrorists always seem one step ahead of us.”

The focus may be wrong. Aviation consultant Michael Boyd calls TSA “the gang that can’t screen straight.” Boyd thinks the new restrictions will inconvenience travelers–without stopping terrorists. “[They] can strap [liquids] to their legs” when they go through security, Boyd says.

The view from inside isn’t much different. “The people who work for [TSA] do a good job. But there aren’t enough of them, things break down and go so slowly, and they don’t have adequate technology,” says a veteran United Airlines pilot, who requested anonymity so he wouldn’t get in trouble with his employer. Under budget pressure, Congress has cut the number of TSA screeners by more than 25 percent since their post-9/11 peak. And the cool, expensive new “puffer” portals that detect explosives residue on individuals are still rare.

Then there’s the problem of air cargo. As they empty their pockets and throw away the bottled water, travelers assume the rest of what’s onboard has been screened, too. Not so. Passenger airlines ship nearly 2 billion tons of commercial cargo annually, and they don’t have machines that can handle the varied shape and content of so many packages. Less than 7 percent is actually screened.

Every year since 9/11, Reps. Edward Markey and Chris Shays have introduced a bill to require the screening of all air cargo, and every year the president and Congress has defeated it because they don’t want to burden the air-shipping industry. Instead, they rely on the “Known Shipper” program, which requires shipping companies to submit details of their operations and undergo random inspections. But overseeing thousands of companies is impossible, and the database of those packages with “elevated risk” has been problematic. Congress cut funding for air-cargo screening in half to $55 million and rejected a 9/11 Commission recommendation that each passenger airliner contain at least one hardened container for suspect cargo. “On this cargo thing, they’re praying,” says Markey. “It’s faith-based homeland security.”

Other aviation threats include inadequate security aimed at airport workers, who are often allowed to approach aircraft without being screened; the rapid proliferation around the world of shoulder-launched missiles and the slow development of onboard counter measures, and weak security at the 6,000 general-aviation airports (private pilots have a strong lobby).

One bright spot is the TSA’s Registered Traveler program, an E-Zpass-style system (already up in Orlando, Fla.) to speed frequent fliers through a special security checkpoint if they’ve been “verified” by the government and a private company. These passengers still go through security, but the process is faster not only for them but also for those in other lines who haven’t paid for the privilege.

It won’t be long before the shock of the London plot wears off and the flying public is less indulgent about the inconveniences of today’s air travel. “We were only just recently allowed to bring tweezers and now this!” Martina Clauser, a Ventura, Calif., accountant, said last week. But Clauser at least kept her sense of humor. “No water? No lotion? We’re Californians. We spend big money keeping soft and hydrated. This is not good. Not good at all.”