Pilots flew into restricted airspace 3,400 times across the country in the three years following the Sept. 11 attacks (search), according to a congressional report that says the government needs to better coordinate its response to such violations.

One agency should be in charge of steering planes away from restricted zones, according to the Government Accountability Office report, obtained by The Associated Press ahead of Thursday's hearing on the subject by the House Government Reform Committee.

Committee Chairman Tom Davis (search), a Virginia Republican, said it's essential for agencies that oversee the skies to work together.

"A quick, coordinated response is absolutely vital if we are faced with a pilot or a plane with hostile intent," Davis said in a statement.

The Federal Aviation Administration (search), the North American Aerospace Defence Command and the Transportation Security Administration are responsible for making sure pilots don't fly where they shouldn't.

Jets have been scrambled more than 2,000 times since the terrorist attack on Sept. 11, 2001, including several well-publicized incidents during which private planes strayed into the restricted zone over Washington, causing the evacuation of the White House, the Capitol and other government buildings.

The GAO said there is no single leader of the airspace security effort.

"Without central leadership, the potential exists for a somewhat slower response to a violation as the agencies decide who is in charge while the violating aircraft continues to operate in restricted airspace," the report said.

The report also said the agencies don't always share information about airspace violations and don't define an airspace violation the same way.

All three agencies took strong exception to the report, saying the current system works well.

"It's been a success," said Master Sgt. John Tomassi of NORAD (search). "Although these things do happen, we can't prevent everything."

"The FAA takes all incursions very seriously," said agency spokesman Greg Martin. "We'll continue to work with the GAO, other federal agencies and Congress to strengthen airspace security even more through better coordination, clarification and information sharing."

TSA spokesman Mark Hatfield said the agency is getting more efficient at responding to airspace violations.

Since the terrorist attacks, the government has vastly expanded the amount of airspace it restricts. Aircraft aren't allowed to fly over nuclear power plants, chemical storage areas, military facilities, the nation's capital or any area where the president is traveling, or events such as the Super Bowl.

On Wednesday, the FAA restricted airspace above wildfires in the West to ensure the safety of airborne firefighting efforts.

The report noted that airspace violations are almost all inadvertent, because a pilot is trying to avoid bad weather or doesn't check for notices of the restrictions, as they're required to do.

Pilots flying private planes are responsible for 88 percent of the violations, and most occur in the eastern United States, where air traffic is heavy and there's a lot of restricted airspace.

Almost half the violations occur around Washington, where pilots aren't allowed to fly in an area of about 2,000 square miles unless they have a special identifying signal and maintain radio contact with the FAA.