At the conference room table was White House Deputy Chief of Staff Joshua Bolten. Bolten watched the exchanges and, after what he called "a quiet moment,"suggested that the Vice President get in touch with the President and confirm the engage order. Bolten told us he wanted to make sure the President was told that the Vice President had executed the order. He said he had not heard any prior discussion on the subject with the President. The Vice President was logged calling the President at 10:18 for a twominute conversation that obtained the confirmation. On Air Force One, the President's press secretary was taking notes; Ari Fleischer recorded that at 10:20, the President told him that he had authorized a shootdown of aircraft if necessary. Minutes went by and word arrived of an aircraft down in Pennsylvania. Those in the shelter wondered if the aircraft had been shot down pursuant to this authorization. At approximately 10:30, the shelter started receiving reports of another hijacked plane, this time only 5 to 10 miles out. Believing they had only a minute or two, the Vice President again communicated the authorization to "engage or "take out" the aircraft. At 10:33, Hadley told the air threat conference call: "I need to get word to Dick Myers that our reports are there's an inbound aircraft flying low 5 miles out. The Vice President's guidance was we need to take them out." Once again, there was no immediate information about the fate of the inbound aircraft. In the apt description of one witness, "It drops below the radar screen and it's just continually hovering in your imagination; you don't know where it is or what happens to it." Eventually, the shelter received word that the alleged hijacker 5 miles away had been a medevac helicopter. Transmission of the Authorization from the White House to the Pilots The NMCC learned of United 93's hijacking at about 10:03. At this time the FAA had no contact with the military at the level of national command. The NMCC learned about United 93 from the White House. 
Where was the President at 10:18 when the Vice President called him?
Air Force One