CNN Probe Finds Weak Link in Air Security

Nearly four years after 9/11, Americans flying on passenger planes remain vulnerable to another terrorist attack in the air because of lax screening of the millions of tons of cargo loaded into the belly of aircraft, a three-month CNN investigation shows.

While screening of passengers and their luggage has been shored up dramatically since hijackers commandeered four planes and crashed them into the twin towers of the World Trade Center, the Pentagon and a Pennsylvania field, little has changed regarding the security of cargo, according to an FAA inspector and the vice chairman of the 9/11 Commission.

On most of the flights that the FAA inspector observes, almost none of the cargo is inspected.

"In respect to cargo, we're probably as vulnerable or more vulnerable," said the inspector, who insisted on not being identified for fear of employer retaliation. "Cargo still has a lot of loopholes where something could get on an airplane."

Former Indiana Rep. Lee Hamilton, the vice chairman of the 9/11 Commission, said the airline industry and the federal government have failed to seriously address the security of air cargo, a multibillion-dollar industry.

"I think this is a point of real vulnerability for America, for the traveling public," Hamilton said. "We are not doing the kind of safety measures that we should be doing to protect the American public."

CNN crisscrossed the country, traveling from one airport to another, and saw firsthand how easy it would be for a terrorist to slip an explosive or lethal chemicals onto an airplane because of holes in the cargo security network.