The E-4Bs NAOC (National Alternate Operations Center) is as ABNCP (Airborne Command Post) platform based out of Offutt AFB, Nebraska. This aircraft is also know as The Doomsday Plane, where in the case of a nuclear attack, war on the United State, a terrorist attack, this plane becomes the flying Pentagon and gives the SecDef and the Joint Chiefs of Staff a way to launch nuclear weapons and communicate to anything, anywhere in the world.
The Boeing E-4 National Airborne Operations Center (NAOC), with the project name "Nightwatch", is an aircraft operated by the United States Air Force (USAF). To create the E-4 series, four Boeing 747-200B airframes were specially modified to serve as a survivable mobile command post for the National Command Authority, namely the President of the United States, the Secretary of Defense, and successors. The four E-4Bs are operated by the 1st Airborne Command and Control Squadron of the 55th Wing located at Offutt Air Force Base, near Omaha, Nebraska. An E-4B is denoted a "National Airborne Operations Center" when in action.
For detailed info: http://en.wikipedia.org/wiki/Boeing_E-4#Design
Upper deck: Flight deck
Middle deck: Conference room, Aft of the conference room is a projection room, Operations team area, Technical Control area, Rest area.
Forward entry area: the main galley unit and stairways to the flight deck and to the forward lower equipment area, NCA area, Briefing room, Communications control area, Flight avionics area
The forward lower equipment room contains the aircraft's water supply tanks, 1200 kVA electrical power panels, step down transformers, VLF transmitter and SHF SATCOM equipment. AC/DC powered hydraulic retractable Airstair is located in the forward right side of the forward lower equipment area, are installed for airplane entry and exit. In the event of an emergency, the airstair can be jettisoned if necessary. The aft lower lobe contains the maintenance console and mission specific equipment.
The lower trailing wire antenna (TWA) area contains the aircraft's 5 mile long TWA reel, which is used by up to 13 communications links -- the antenna operator's station, as well as the antenna reel controls and indicators. Much attention has been given to hardening this area against EMP, especially as the TWA, essential for communicating with ballistic missile submarines, is also particularly effective in picking up EMP.