A Massive Flying Fortress
Not only does Air Force one function as a means of travel to and from crucial destinations, but it also serves as a flying fortress to protect and secure the POTUS and any fellow passengers. Each and every window on the aircraft is armored and resistant to gunfire. There are flares that can be released from the craft, if needed, that will aid in confusing any enemy missiles. Finally, as a means to keep down on possible sabotage, both exits from Air Force one has its own retractable staircase, preventing the necessity to depend on airport staircases.
Image: WTTE