Tampa, Florida-- There is heightened concern terrorists may be planning another 9/11 type of attack- even using airplanes again.

The 10 News Investigators recently obtained an internal memo that security experts of the U.S. Airline Pilots Association and Federal Air Marshalsbelieve details a terrorist "dry-run" that happened just six weeks ago on a flight from Reagan National Airport to Orlando International Airport.

STORY:10 News Investigators find memo warning about terrorist "dry-runs" on airplanes
READ:The Security Update Memo(PDF)

Following our story, there has been a Congressional call for an investigation.

Orlando Congressman John Mica says information of this nature must be properly investigated and federal authorities must review the matter.

The Transportation Security Administrationalso issued a statement, saying the agency "takes all reports of suspicious activity on board aircraft seriously." The statement also added that with assistance from law enforcement, "the matter required no further investigation at this time."

Experts say the incident could be an indication of another attempt to blow up an airplane in mid-air, and if that occurs on a flight with a federal air marshal aboard, there most likely will be gunfire in the airplane.

See also: TIA passengers react to news of possible terrorism threat

A Federal Air Marshal explained why that would be the case. 10 News is concealing his identity because he is not authorized to talk to the media.

"If the bad guys are there and they do what they're going to do, our job is to kill them," he said.

The marshal also said if he doesn't kill a bad guy trying to take over an airplane, he would be dead.

As a training video we obtained shows, Federal Air Marshals are trained that the terrorists' first order of business is to identify and kill the marshals aboard a flight.

That's why there is so much concern about the incident last month on US Airways flight 1880.

According to the memo from the U.S. Airways Pilot Union Security, several "middle eastern men" caused a commotion and appeared to be doing a dry run to test procedure and reaction to an in-flight threat.

"They are trying to pull out air marshals if they are on board, or law enforcement if they are on board. They are looking for how the crew reacts," the air marshal explained.

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Retired Colonel Mike Pheneger, who was the Director of Intelligence at Special Operations Command, said it can be difficult to stop an attack.

"You can't absolutely ensure your ability to stop a terrorist attack, it's impossible."

Pheneger said not only is it likely terrorists will try to blow up an airplane, but also it is a monumental task to thwart.

"We can only make it more difficult for people to attack an airplane or a facility. We can't make it impossible," said Pheneger. "We have to be lucky 100 percent of the time and they only have to be lucky once."

And an airline ground crew veteran we talked to said while the public is screened, the ground crew is not, and could plant weapons or bombs in the lavatory.

"We could just carry our backpacks right through the turn style gate and could have anything we wanted to put on that plane."

But despite the threat, Pheneger said your odds of being on a plane taken over by terrorists are slim, "...but somebody is eventually going to be unlucky, and that will happen- and I'm surprised quite frankly it hasn't."

Since our original story, we have received several emails and phone calls from both passengers and flight crews who say they were on flights that frightened them, and appeared to be a dry-run.

The Air Marshals say there was an incident on a recent flight where a "middle eastern man" stood at the front bathroom and stared down the air marshal to the point the air marshal slowly unloosened his seat, put his hand on his weapon and was ready to fire and then man went back to his seat.

TSA officials, US Airways representatives and Congressman John Mica have provided statements in response to our investigation. You can read each statement in its entirety below:

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