WASHINGTON, June 21: US Air National Guard fighter jets were scrambled into the air too late from nearby Andrews Air Force Base on Wednesday night to protect the White House from a small plane that wandered into restricted airspace over Washington, US officials said on Thursday.

The officials told Reuters that two F-16 fighters took off 11 minutes after ordered — well within the 15-minute time period allowed to respond to emergencies — but did not reach the scene until the small plane had flown into and out of a “prohibited area” within eight kilometres of the presidential mansion.

The White House was evacuated for 15 minutes when the Cessna aircraft flew into the restricted airspace by accident, but President George W. Bush was never in danger, officials said.

The small plane entered restricted airspace at 7:59 p.m. EDT and flew out at 8:13 p.m. The jets did not take off from Andrews until 8:17 p.m., according to the officials, who asked not to be identified.

“This illustrates just how hard it is to do this kind of thing, especially in a busy air traffic area,” said one of the officials.

The Federal Aviation Administration, the military and other agencies have set up tightly restricted non-flight zones over parts of Washington, New York and other areas of the country after the Sept. 11 attacks in which hijackers crashed airliners into buildings, killing more than 3,000 people.

FAA spokesman Bill Shumann said on Thursday that the agency was investigating the incident as a “pilot deviation.” Depending on the seriousness of the violation, the result could be anything from no action to a reprimand letter or even a license suspension or revocation, he said.

Here is a timeline of Wednesday’s incident provided to Reuters by US officials:

7:59 p.m. EDT: The single-engine private aircraft enters a 24-km zone of temporary flight restricted (TFR) airspace around the Washington Monument.

8:03 p.m.: The FAA notifies the joint North American Aerospace Defense Command (NORAD) based in Colorado that the wider air zone has been violated.

8:06 p.m.: NORAD orders F-16s to take off from Andrews as the Cessna flies into an even more tightly restricted “prohibited area” only 8 kms from the White House.

8:13 p.m.: The Cessna flies out of the 15-mile (24-km) TFR zone.

8:17 p.m.: The F-16s take off from Andrews, later catch up with the Cessna near Fredericksburg, Virginia, south of Washington, and escort it to a landing at Richmond, Virginia.—Reuters