In the wake of the Russian Metrojet crash and the Paris terror attacks, security while flying in the U.S. is of greater concern than ever. Yet in Atlanta, a man said he accidentally carried a loaded gun onto a commercial flight and the TSA never found it.

TODAY national investigative correspondent Jeff Rossen and the Rossen Reports team went undercover at several airports across the country to see how well the TSA performed. In three out of four cases, they were able to get banned items past TSA inspection.

At Los Angeles International Airport, Rossen put a Swiss Army knife in his bag and was stopped by inspectors, who confiscated the knife.

However, at Atlanta International Airport, a Rossen Reports producer was able to get through TSA inspection with a Swiss Army knife in her wallet. Also in Atlanta, another member of the Rossen team got through security with a sharp scissors whose blade was longer than 4 inches.

Among the items Rossen Reports was able to get past TSA screening: a pair of scissors with a blade longer than 4 inches, and a box cutter. TODAY

And at Newark Liberty International Airport, a Rossen producer got onto his flight with a box cutter — the same weapon used by hijackers in the 9/11 attacks.

Reviewing the results, aviation security expert Anthony Roman called them "a complete and utter failure of the system."

In a statement to NBC News, TSA Administrator Peter Neffenger said: "It is unacceptable for any prohibited item to pass through security undetected. Both the DHS Office of the Inspector General and TSA frequently conduct testing and evaluations of our screening measures so that we can continuously improve our security screening procedures. As a result of this input, TSA has been implementing systematic changes in how we screen passengers and their baggage in order to better deter, detect, and disrupt any potential threat of terrorism.”

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