Military personnel responsible for defending U.S. airspace had false tracks displayed on their radar screens throughout the entire duration of the 9/11 attacks, as part of the simulation for a training exercise being conducted that day. Technicians at NORAD's Northeast Air Defense Sector (NEADS) were still receiving the simulated radar information around the time the third attack, on the Pentagon, took place. Those at NORAD's operations center in Cheyenne Mountain, Colorado, were still receiving it several minutes after United Airlines Flight 93 apparently crashed in rural Pennsylvania.

No one has investigated why false tracks continued being injected onto NORAD radar screens long after the U.S. military was alerted to the real-world crisis taking place that morning. And yet we surely need to know more about these simulated "inputs" and what effect they had on the military's ability to respond to the 9/11 attacks.

NEADS TECHNICIANS TOLD TO TURN OFF 'SIM SWITCHES'

Several hours after the 9/11 attacks in New York and Washington occurred, a passenger aircraft heading to the U.S. from Seoul, South Korea, was mistakenly considered hijacked. In a little-reported series of events, the pilots of Korean Airlines Flight 85 gave numerous indications that their plane had been taken over by hijackers, even though it had not. KAL 85, a Boeing 747 that had been due to land in Anchorage, Alaska, for a refueling stop, was consequently diverted to an airport in Canada. The military launched fighter jets to tail it and, with authorization from the Canadian prime minister, threatened to shoot the plane down if it refused to change course. Only after KAL 85 landed were officials able to confirm that no hijacking had taken place.

While a person might suggest this crisis was just the result of confusion due to the unprecedented events earlier that day, the number of indications the pilots gave that their plane was hijacked, and their repeated failure to confirm that this was not the case, raises another possibility: Could KAL 85 have been playing the part of a hijacked aircraft in a military training exercise?