But while travelers endure tighter and tighter security at the front doors of most airports, CBS News has learned the backdoors and perimeters of airports across the country have less and less security. Employees say there are gaps that place passengers and planes at risk.
Travelers see the barbed wire, gates and guards, but workers at the nation's airports say the public is being lulled into a false sense of security: No one is watching the perimeter at most airports.
"There's opportunity for a terrorism attack. There's opportunity for someone to do something that could put everyone in harm's way," says Dianna Rushing, who represents flight attendants at Chicago's O'Hare Airport.
The flight attendants Rushing represents are upset about an employee gate where workers - some of whom it recently turned out were illegal aliens – have to show only an ID but get no screening. They just head into secure areas. More troubling, cars and trucks are rarely inspected.
Federal law requires perimeter security be as tough as terminal security: There should be "screening or inspection of all individuals ... vehicles and other equipment before entry into a secured area of an airport."
But CBS News Correspondent Vince Gonzales and his crew were able to drive through that gate, saying they were lost.
"We're in, and if we wanted to … we could go right into the airport," said Gonzales, after going through the gate.
Gonzales and his crew left the area, but not far away heavy trucks barreled through an unguarded construction gate and into an area very close to runways.
At Dallas-Ft. Worth Airport, close to 1,000 construction workers enter the property everyday unscreened. Their coolers and toolboxes are not searched. Meanwhile, potential threats, including propane tanks and fuel trucks, are left unguarded.
"Right now we're in an area that's supposed to be secure," Gonzales said from inside the gate. "No one is supposed to be able to get at equipment like this and yet, if we wanted to - if we had the tools - we could probably steal this truck and take it anywhere in the airport, even very close to the flight line."
Gates were also open and unguarded at a construction site very close to runways. DFW says workers are screened before entering high security areas, but construction sites inside the airport have different rules.
"The regulations regarding our perimeter are totally and distinct from a regulatory point of view than anything to do with a construction site," says Alvy Dodson, DFW vice-president of public safety.
At Chicago's O'Hare officials say they believe the airport is in compliance with all federal security regulations and they are doing everything to meet those standards. The International Association of Flight Attendants says only San Francisco and Denver have complied with federal law and fixed perimeter security.
"As far as we know every other airport in the country is just as wide open as it was before Sept. 11," says Rushing.
According to federal documents, flight crews have been warning the government for years. One pilot wrote of airport perimeters: "There is no security." Another said: "Airport security is a joke."