Ok I feel so safe now. Too Late to Help Plane Leaves White House Airspace Before F-16s Arrive W A S H I N G T O N, June 20 â€” The small single-engine plane that wandered into restricted Washington airspace Wednesday could have rammed the White House before responding F-16 fighter jets had even left the ground, government officials told ABCNEWS. The White House also acknowledged today that President Bush was not informed of the incident until this morning, even though it prompted a partial evacuation of the building. The plane â€” a wayward single-engine Cessna aircraft â€” was escorted without incident to Richmond International Airport, but it highlighted the ongoing security threat posed by small aircraft. White House officials defended their response to Wednesday's incident. "The reason the president was neither told nor moved, was because the judgment was made accurately so that the plane did not pose a threat," White House spokesman Ari Fleischer said. The aircraft was heading south along the East Coast when it veered into the Temporary Flight Restriction Zone in Washington just before 8 p.m. Wednesday. The 15-mile TFR zone was implemented after Sept. 11 to provide additional security for the White House. The Secret Service told ABCNEWS the plane "skirted" the smaller permanent restricted airspace at 10,300 feet, inside the TFR zone. The agency decided then to move press personnel, visitors and staffers onto the South Lawn. Plane Ignored Messages From Tower Officials were primarily concerned because the plane did not respond to instructions from air-traffic controllers, but it was never on a direct course for the White House, Secret Service officials said. The pilot, Kevin McCole, finally contacted the tower at Reagan National Airport asking about weather conditions. He was informed he was in restricted airspace and then changed his course. Two F-16 fighter jets reached the plane in just 11 minutes, but McCole had already steered his craft out of the restricted airspace several minutes earlier. Even with anti-aircraft missiles mounted along the Potomac River, it would still be nearly impossible to respond fast enough to this kind of potential threat, the administration concluded after a post-Sept. 11 review, sources tell ABCNEWS. The time required to assess a threat, obtain to respond, and then arm and fire a weapon is simply too great, officials concluded. There have been some 11 incidents of unauthorized planes entering the TFR zone since Sept. 11, officials tell ABCNEWS, but Wednesday's incident drew more concern because the pilot did not immediately respond to air-traffic controllers. Experts stressed that even nine months after Sept. 11, it would take more time to fortify homeland defenses. "The idea that we can quickly create effective homeland defense is simply totally unrealistic. We can't even begin to spend most of the money in less than a year," ABCNEWS military analyst Anthony Cordesman. ABCNEWS' Dennis Powell, Katy Textor, and John McWethy contributed to this report. White House Aircraft Timeline Following is a timeline of the Wednesday's incident in restricted airspace near the White House: 7:59 Baltimore air traffic controllers notified Reagan National Airport controllers that an unidentified plane was heading toward Washington. 7:59 - 8:01 National Airport ATC tries to raise the plane on a number of frequencies, but are unable to contact the pilot. 8:01 The plane enters the Temporary Flight Restriction Zone around the White House. National Airport officials contact both the Secret Service and the North American Aerospace Defense Command (NORAD), which is responsible for airspace security. Defense Department sources say NORAD was notified at 8:03, and that the plane entered the TFR zone at 8:04. 8:06 NORAD orders F-16s scrambled, according to Defense Department sources. 8:13 Cessna leaves TFR Zone after air traffic controllers finally reach the pilot, and he is notified of the violation and told that fighter jets had been scrambled. 8:17 F-16s are airborne, according to Defense Department Sources. 8:24 Fighters make visual contact with Cessna near Fredericksburg, Va.