In an at times contentious hearing, military and law enforcement officials acknowledged that a small helicopter was too small to be detected by radar and other security assets as it flew to the nation's capital and ultimately landed it on the lawn of the U.S. Capitol.

"This is not good," said Rep. Stephen Lynch (D-MA), who said it reminded him of how the U.S. was not vigilant enough before the Nine Eleven terrorist attacks.

"I get the sense that we are behind the curve again," Lynch said at a hearing of the House Oversight Committee.

Witnesses told lawmakers that the gyrocopter was too small, so it didn't show up on radar like a small plane would.

"It actually had much more in common with a weather system," said FAA chief Michael Huerta, who said a review showed the gyrocopter appeared as an "unidentified radar element."

"But the dot appeared only intermittently," Huerta said, relating the findings of a full review of radar data on how the gyrocopter flew from Gettysburg, Pennsylvania to the U.S. Capitol.

The answers did not please lawmakers of either party.

"If the gentleman (Hughes) had wanted to, he could have crashed into the Capitol," said Rep. Mick Mulvaney (R-SC).

"This knucklehead with a gyrocopter could easily have been a terrorist," said Rep. Matt Cartwright (D-PA).