Officials: Government failed to react to FAA warning

Smoke billows from the Pentagon on Tuesday, after it was struck by United Airlines flight 77.

WASHINGTON (CNN) -- The federal government failed to heed a warning from the Federal Aviation Administration (FAA) to evacuate key Washington buildings following Tuesday's terrorist attacks on the World Trade Center, senior Defense Department officials told CNN.

The officials said no action was taken for at least 12 minutes after the FAA warned the military's air defense command that a hijacked airliner appeared to be headed toward Washington.

Only after the 9:38 a.m. impact into the side of the Pentagon were other government buildings evacuated, including the White House and the Capitol.

The North American Aerospace Defense Command (NORAD) at Peterson Air Force Base in Colorado was informed by the FAA at 9:25 a.m. that American Airlines flight 77 might have been hijacked and appeared headed toward Washington.

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Military officials at NORAD ordered fighter jets from Langley Air Force Base in Virginia to intercept the flight, but neither the FAA, NORAD, nor any other federal government organization made any effort to evacuate the buildings in Washington.

Officials at the Pentagon said that no mechanism existed within the U.S. government to notify various departments and agencies under such circumstances.

Officials also told CNN that President George W. Bush had not given authorization to the Defense Department to shoot down a passenger airliner until after the Pentagon had been struck.

Officials at the Pentagon also said that they were never made aware of the threat from hijacked United Airlines flight 93 until after it crashed in Pennsylvania.

The informed defense officials laid out a timeline of the events surrounding the series of terrorist attacks as follows: (Times are EDT and reflect actual, rather than scheduled departure times of flights.)

--7:59 a.m.: American Airlines flight 11 takes off from Boston's Logan International Airport.

--8:14 a.m.: United Airlines flight 175 takes off from Boston's Logan International Airport.

--8:20 a.m.: American Airlines flight 11 stops transmitting IFF beacon signal while over the Hudson River.

--8:20 a.m.: American Airlines flight 77 departs Dulles International Airport near Washington.

--8:38 a.m.: Boston air traffic center notifies NORAD that American Airlines flight 11 has been hijacked.

--8:43 a.m.: FAA notifies NORAD that United Airlines flight 175 has been hijacked.

--8:44 a.m.: Otis Air National Guard Base in Mass. orders to fighters scrambled.

--8:46 a.m.: American Airlines flight 11 strikes the World Trade Center's north tower.

--8:47 a.m.: NORAD informed of the plane striking the World Trade Center.

--8:50 a.m.: United Airlines flight 175 deviates from its assigned flight path.

--8:52 a.m.: Two F-15 Eagles take off from Otis ANG Base in effort to intercept hijacked plane(s) after first plane has struck the World Trade Center.

--9:02 a.m.: United Airlines flight 175 strikes the World Trade Center's south tower (F-15 fighter jets from Otis ANG Base are still 70 miles away.)

--9:25 a.m.: FAA notifies NORAD that United flight 77 may have been hijacked.

--9:27 a.m.: (approximate time) NORAD orders jets scrambled from Langley Air Force Base in Virginia to head to intercept United Airlines flight 77.

--9:35 a.m.: Three F-16 Fighting Falcons take off from Langley AFB headed toward Washington area.

--9:37 a.m.: American Airlines flight 77 is lost from radar screens.

--9:38 a.m.: American Airlines flight 77 strikes the Pentagon.

--9:49 a.m.: F-16 fighter jets arrive over Washington, D.C. to perform Combat Air Patrol (CAP) over city. (The fighters broke the sound barrier and traveled supersonic at 720 knots to Washington, making the approximately 130 miles in 14 minutes.)

The following timeline is for United Airlines flight 93, scheduled to fly from Newark International Airport to San Francisco. The flight crashed in Pennsylvania.

--8:42 a.m.: United Airlines flight 93 takes off from Newark International Airport.

--9:16 a.m.: FAA informs NORAD that United Airlines flight 93 may have been hijacked.

--9:40 a.m.: Transponder signal from United flight 93 ceases and radar contact is lost.

--10:02 a.m.: After a review of radar tapes, a radar signal is detected near Shanksville, Pennsylvania.