In his book Black Ice, author Dan Verton identifies this aircraft as an E-4B taking part in the 2001 operational exercise "Global Guardian". The exercise was canceled when the first plane struck the World Trade Center, and the E-4B, operating under call sign "Venus 77", which was waiting on the ramp at Andrews AFB, requested emergency clearance and immediately took off. The aircraft initially requested clearance for a direct route to Wright-Patterson AFB, in Dayton, Ohio, and was in the process of receiving clearance while it was seen circling the capital at low altitude during the attack on the Pentagon. Four minutes later the aircraft requested clearance to circle sixty miles south of Washington D.C. Eight minutes after takeoff the aircraft requested clearance to circle Richmond, Virginia at an altitude of 19,000, where it remained for the duration of the attack.[12]