http://www.aljazeera.com/cgi%2Dbin/conspiracy%5Ftheory/fullstory.asp?id=305

On October 26, 1999, the famous golfer Payne Stewart boarded a private Learjet in Florida and left for Texas. Shortly after takeoff, Stewart's jet veered sharply off course and began heading northwest. All contact with air controllers was lost. Within 15 minutes of having gone off course, US fighter jets had already intercepted the jet.

These fighter jets were dispatched by NORAD, the branch of the US air force whose job is to monitor and defend US airspace 24 hours a day. NORAD maintains a huge array of land based radar systems and has fighter jets on alert 24 hours a day so that they can respond to any crisis.
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The quick reaction time and military precision with which NORAD intercepted and escorted Stewart's jet was impressive, and exactly what one would have expected from the greatest military power in world history.

But on 9-11, the same NORAD which had so effortlessly intercepted Stewart's jet in 1999, was nowhere to be found during that two hour period between the first planes going off course and the last one crashing in a Pennsylvania field. How is it possible that the airspace between Boston and Washington DC, an area which contains the political and economic heart of the nation, was left completely defenseless? The second plane to hit the New York had flown off course without communication for 40 minutes. On its way to New York, it actually flew within a few miles of McGuire Air Force base in New Jersey, after the first tower had already been hit! And how is it possible that Washington DC was left undefended (long after the New York attacks) when Andrews Air Force base is within car driving distance?