Boeing E-4 Command Post Military Aircraft
The Boeing E-4 Advanced Airborne Command Post, with a project name of "Nightwatch", is an aircraft operated by the United States Air Force (USAF). To create the E-4 series, four Boeing 747-200 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 E-4B is designed to survive an EMP with systems intact, and has state-of-the-art direct fire countermeasures. The E-4B uses analog instruments because they are less susceptible to an EMP. The E-4B is capable of operating with a crew of 48 to 112 people, the largest crew of any aircraft in US Air Force history. With in-flight refueling it is capable of remaining airborne for a considerable period (limited only by consumption of the engines' lubricants). In a test flight for endurance, the aircraft remained airborne and fully operational for 35.4 hours. It takes two fully loaded KC-135 tankers to fully refuel an E-4B.
The E-4 fleet was originally deployed in 1974, when it was termed National Emergency Airborne Command Post or NEACP (often pronounced "kneecap"). The aircraft was to provide a survivable platform to conduct war operations in the event of a nuclear attack. Early in the operations of the E-4, the media dubbed the aircraft as "the doomsday planes".
The aircraft were originally stationed at Andrews Air Force Base in Maryland, so that the U.S. President and Secretary of Defense could access them quickly in the event of an emergency. The origin of the name "Nightwatch" comes from the richly detailed Rembrandt painting of the same name depicting local townsfolk protecting a town and was selected by the Squadron's first commanding officer. Later, the aircraft were moved to Offutt Air Force Base where they would be safer from attack. Until 1994, one E-4B was stationed at Andrews Air Force Base at all times so the President could easily board it in times of world crisis.
When a President boards the E-4, its call sign becomes "Air Force One". (NEACP aircraft originally used the static callsign "Silver Dollar"; this callsign faded from use when daily callsigns were put in use.) The E-4B also serves as the Secretary of Defense's preferred means of transportation when traveling outside the United States. The spacious interior and sophisticated communications capability provided by the aircraft allow the Secretary's senior staff to work for the duration of the mission.
All E-4s were converted to B-models by 1985. With the adoption of two highly-modified Boeing 747-200Bs (known as VC-25A in Air Force parlance) to serve as Air Force One in 1989, and the end of the Cold War, the need for NEACP diminished. In 1994, NEACP began to be known as NAOC, and it took on a new responsibility: ferrying Federal Emergency Management Agency crews to natural disaster sites and serving as a temporary command post on the ground until facilities could be built on site. Evidently no E-4B was employed during the Hurricane Katrina Disaster of 2005, though one E-4B was used by FEMA following Hurricane Opal in 1995. The "cocked" or "on alert" E-4B is manned 24 hours a day with a watch crew on board guarding all communications systems awaiting a launch order (klaxon launch). Those crew members not on watch would be in the alert barracks, gymnasium, or at other base facilities. The 24 hour alert status at Andrews AFB ended when President Clinton ordered the aircraft to remain at Offutt unless needed, though relief crews remain based at Andrews and Wright-Patterson Air Force Base. One E-4B is kept on alert at all times.