Ten years ago this month, Congress created the Transportation Security Administration to seal the gaps that allowed 19 terrorists to turn four U.S. airliners into missiles and kill thousands. But today, the TSA is a bloated and ineffectual agency with an $8 billion annual budget and a record of embarrassing missteps and narrowly avoided disasters.

It is a scorching summer day at New York's Kennedy Airport, and as jetliners queue up in the afternoon haze, the tantalizing waters of Jamaica Bay lie out of reach, separated from the runway and the rest of the airport grounds by an eight-foot-tall security fence. But, as is true for much of airport security these days, the secure perimeter is an illusion: For several months earlier this year, a sizable swath of this critical fence was in tatters, damaged by storms and ensuing neglect. An internal JFK police report and photographs obtained by Condé Nast Traveler reveal that earlier this year, patrolling officers were aware of at least two gaps in the fence that "anyone can easily walk through" to access runways and other secure areas. In fact, in mid-July an intruder did swim his way onto the grounds of JFK, where he sneaked past the chain-link barricade and dashed toward the airport's sprawling fuel depot. He was spotted by police, but lacking a weapon and even a stitch of clothing, he hardly fit the profile of a terror suspect. With sabotage quickly ruled out, it was just another "breach" in airport security, to be filed away and quickly forgotten.

Or maybe not: Ten years after Congress created the TSA, many of its early supporters, including a number of those who helped to bring it into being, are turning on the agency for what is widely viewed as a series of blunders. At a House of Representatives hearing last July, lawmakers took turns venting their outrage. "This is a system that is designed to hassle everyone, and yet we're still not able to prevent these [breaches]," said Rep. Jason Chaffetz (R-Utah), chairman of the House Subcommittee on National Security, Homeland Defense, and Foreign Operations. According to data released by the congressman, 25,000 breaches of airport security have occurred at U.S. airports since 9/11, some 1,300 of them involving people who trespassed onto secure areas. The vast majority were insignificant lapses resulting from passenger confusion, the TSA claims. "They represent a tiny fraction of one percent of the more than 5.5 billion travelers we have screened effectively since 9/11," says agency spokesman Greg Soule, adding that most of those committing the breaches were immediately discovered and thwarted. But the trespasser tally also includes at least two cases in the last year of stowaways who managed to sneak into the wheel wells of planes parked at JFK and Charlotte airports. (Neither was found before takeoff, and both died before making it to their destination.) Other recent incidents were also far from benign: At Newark Airport, a knife-wielding intruder recently got onto the tarmac by scaling an eight-foot fence (he was arrested and jailed), and at Dallas/Fort Worth, a group of youths pulled off a brazen bypass of all security and, in a bizarre coda, posted a video of their exploits on YouTube.

"It's like a person trying to defend his home by spending all his resources on the front door while leaving the back door wide open," says security expert Rafi Ron, former director of security at Tel Aviv's Ben Gurion Airport. "Most of the TSA's effort has been directed at passengers and their bags, and little of it has been focused on securing the rest of the airport." The vast majority of airports in the United States, he says, "do not have the ability to prevent an intruder from entering the secure side of the airport through a fence or a waterfront." In fact, more than three-quarters of the airports in the United States have never had the mandated joint FBI-TSA audit that should have been completed years ago—inspections which might have uncovered flaws like the fence at JFK, where an elaborate antiterrorist surveillance system that employs motion sensors, cameras, and alarms to guard airport grounds is years behind schedule. (Airport officials say that the holes have been fixed.)