In a former life in the Navy, I was posted to our embassy in DC. There was a small group of foreign NCOs who were able to visit various US Defence facilities from time to time, and one of the places we visited was AAFB. This was at the height of the Cold War, and though AF1 was very securely surrounded by a massive chain link fence, and guarded by US Marines, we were able to board AF2, which in those days was a B707. Still have a pic of me and the rest of the group on the stairs dis-embarking. We were told that if the balloon ever went up, the Pres would be immediatley choppered to AAFB and would take to the air for the duration of the threat. As someone has stated above, AF1 was fitted with inflight refueling, and once airborne, a massively long antenna would be cranked out to enable comms to all and every one of their Defence units, including submarines, anywhere in the world. The plan was that AF1 would be constantly refuelled until either the war was won, or the engines siezed up, whichever came first. From memory, we were told that the AF2 we visited had been AF1 in it's former life.