Boeing E-4

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E-4B “Nightwatch”


E-4B in flight


Airborne Command Post






2012 (programmed)


In Service

Primary user

United States Air Force

Number built


Unit cost

US$250 million

Developed from

Boeing 747


Boeing VC-25

The Boeing E-4B Advanced Airborne Command Post, with a project name of “Nightwatch”, is an aircraft operated by the United States Air Force and is specially built to serve as a survivable mobile command post for the National Command Authority (the President of the United States and the Secretary of Defense, and successors).


The airframe is a Boeing 747-200 aircraft specially built to serve as a survivable mobile command post for the National Command Authorities (the President of the United States and the Secretary of Defense, and successors). Other support staff would board the aircraft such as members of the Joint Chiefs of Staff. The primary purpose of 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 series, the media dubbed the aircraft as “the doomsday planes.” Four are currently operated by the United States Air Force, and are assigned to the 1st Airborne Command Control Squadron (1ACCS) of the 55th Wing at Offutt Air Force Base, Nebraska. Maintenance and crews are provided by Air Combat Command, while operations are coordinated by United States Strategic Command. The first mission for the aircraft was known as NEACP (National Emergency Airborne Command Post – pronounced “kneecap”). As the Soviet nuclear threat diminished in the 1990s, the aircraft mission was modified to support the Federal Emergency Management Agency (FEMA) and renamed NAOC (the National Airborne Operations Center). Previous NEACP aircraft used the static callsign “Silver Dollar”, this callsign faded from use when daily callsigns were put in use.

Two US Presidents have flown on the E-4, President Jimmy Carter and President Ronald Reagan. When a President boards the E-4, the callsign becomes “Air Force One”, as the E-4 is an Air Force aircraft. It is due to retire around 2015.


Two of the original 747-200 airframes were destined to be commercial airliners. When the airline did not complete the order, Boeing offered the airframes to the USAF as part of a package leading to a replacement aircraft for the then used NEACP EC-135J model. The first E-4A was completed at the Boeing plant outside Seattle, Washington in 1974. The “A” model effectively housed the same equipment as the EC-135, but offered more space and an ability to remain aloft longer than an EC-135. Additionally the E-4 was capable of operating the “Looking Glass” mission of the Strategic Air Command (SAC). The E-4A aircraft were capable of remotely launching retaliatory strikes from SAC missile fields. (In time SAC relinquished the aircraft to full time use by the OJCS.) Two more E-4As were built by Boeing. In 1979 Boeing built the first E-4B, which was distinguished from the earlier version by the presence of a large “hump” on the dorsal surface directly behind the upper deck. This contains the aircraft’s (SHF) satellite antenna. By 1980 all three E-4A’s had been retrofitted to E-4B models. The E-4B offered a vast increase in communications capability than the previous model and was considered to be ‘hardened’ against the effects of electromagnetic pulse (EMP) from a nuclear blast. Hardening the aircraft meant that all equipment on board were shielded from EMP. Additional steps were taken to block radiation from the aircraft’s cabin air management system.

Estimates at the time of the production of the first E-4B placed the developmental cost at nearly 1 billion dollars (US). The roll out cost of the fleet was placed at approximately US$250 million each. The E-4B is capable of operating with a crew of 60 to 114 people, the largest crew of any aircraft in US Air Force history.

Station layout

The E-4B has three operational decks:

Upper Deck

The Flight Deck

The flight deck contains the pilot’s, copilot’s, navigator’s and flight engineer’s stations. A lounge area and sleeping quarters for flight crews and other personnel are located aft of the flight deck.

Middle Deck

The Conference Room/Projection Room

The middle deck contains the conference room, which provides a secure area for conferences and briefings. It contains a nine-position executive conference table with executive chairs. Aft of the conference room is a projection room serving the conference room and the briefing room. The projection room has the capability of projecting computer graphics, overhead transparencies or 35mm slides to either the conference room or the briefing room either singularly or simultaneously.

Operations Team Area

Behind the projection room is the operations team area containing the automatic data processing equipment and seats and console work areas for 29 staff members. The consoles are configured to provide access to or from the automated data processing, automatic switchboard, direct access telephone and radio circuits, direct (“hot”) lines, monitor panel for switchboard lines, staff and operator inter-phone and audio recorder.

Control Area

The aft end of the main deck is divided into a technical control area and a rest area. The enclosed technical control area, which occupies the left forward part of the compartment, contains a technical control console, multiplexer, SHF SATCOM, console, and patch and test assembly.

Rest Area

The rest area, which occupies the remaining portion of the aft main deck, provides a rest and sleeping area for the crew members.

Forward Entry Area

Within the forward entry area is the main galley unit and stairways to the flight deck and to the forward lower equipment area. This area contains refrigerators, freezers, a convection oven and a microwave oven to give stewards the capability to provide more than 100 hot meals during prolonged missions. Additionally, four seats are located on the left side of the forward entry area for the security guards and the stewards.

NCA Area

Behind the forward entry area is the NCA area, which is designed and furnished as an executive suite. It contains an office, a lounge and sleeping area, and a dressing room. Telephone instruments in this area provide the NCA with secure and clear worldwide communications.

Briefing Room

The briefing room contains a briefing table with three executive seats, eighteen additional seats, a lectern and two rear projection screens.

Communications Control Area

The communications control area is divided into a voice area and a data area. The voice area, located on the right side of the compartment, contains the radio operator’s console, the semi-automatic switchboard console and the communication officer’s console. The data area, located on the left side of the area, contains the record communications console, record data supervisor’s console, high speed DATA/AUTODIN/AFSAT console and LF/VLF control heads.

Flight Avionics Area

The flight avionics area contains the aircraft systems power panels, flight avionics equipment, liquid oxygen converters and stowage for baggage and spare parts.

Lower Deck

Forward Lower Equipment Room

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. Electrically operated retractable stairs, located in the forward right side of the forward lower equipment area, are installed for airplane entry and exit.

The Aft Lower Equipment Area

The aft lower equipment area contains the maintenance console and mission specific equipment.

The Lower Antenna Area

The lower trailing wire antenna area contains the aircraft’s 5 mile long trailing wire antenna reel, the antenna operator’s station as well as the antenna reel controls and indicators.


A right front view of a Boeing E-4 advanced airborne command post (AABNCP) (b/n 75-0125) on the electromagnetic pulse (EMP) simulator for the testing.

A right front view of a Boeing E-4 advanced airborne command post (AABNCP) (b/n 75-0125) on the electromagnetic pulse (EMP) simulator for the testing.

The E-4B is designed to survive an electromagnetic pulse (EMP) with systems intact, and has state-of-the-art direct fire countermeasures. With in-flight refueling it is capable of remaining airborne for a considerable period (limited only by corruption of the engines’ lubricants). In a test flight for endurance, the aircraft remained airborne and fully operational for 33 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 NEACP (National Emergency Airborne Command Post). Originally stationed at Andrews Air Force Base in Maryland, alongside Air Force One, so that the President and Secretary of Defense could access it quickly in the event of an emergency. 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. The “cocked” or “on alert” E-4B was 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 located in the alert barracks, gymnasium, or at other base facilities. Given the nature of the mission, tests were often carried out where the crew would respond to the aircraft triggered by the sound of a loud klaxon. These tests often happened during nighttime hours, when directed by a higher authority, or when certain communications links failed. From time to time, special mission practice events occurred. There were two prominent special missions code-named “OPAL” and “JEEP”. OPAL was a simulated arrival of the President brought to the E-4B location by Marine One, a helicopter operated by Marine Helicopter Squadron 1 (HMX-1). Occasionally this might include a no-notice launch and exercise with a surrogate President. JEEP exercises would be similar but the intent was to test an evacuation of high ranking government officials, including the Defense Secretary or Presidential successors. 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 full alert at all times.

With the adoption of two highly-modified Boeing 747-200Bs (known as VC-25Aa 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.

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.

The E-4B is often responsible for Air Force One sightings. The E-4B was sometimes used by former Secretary of Defense Donald Rumsfield as his preferred means of transportation when traveling outside the United States. No less than 60 crew members must accompany the aircraft whenever he uses it, more than usually required to operate Air Force One.

The aircraft and mission are to be phased out beginning in 2009 and ending in 2012.

Recent Developments

In January 2006 Donald Rumsfeld announced that the entire E-4B fleet will be retired starting in 2009. One aircraft will be eliminated from inventory each year, with the last aircraft to be retired in 2012. They may be replaced by two Boeing C-32’s upgraded to provide broadcasting capabilities for the president in the event of nuclear war or a national emergency. These aircraft will not have the sophisticated command and control capabilities of the current E-4B fleet, although several E-8’s may be upgraded to similar command capabilities, though not designed to accommodate the presidential staff in the event of a national emergency.

Popular culture

The E-4B plays a prominent role in two motion pictures, appearing in the HBO film “By Dawn’s Early Light,” and “The Sum of All Fears,” based on the book by Tom Clancy.

Specifications (E-4B)

General characteristics

  • Crew: 60-114
  • Length: 231 ft 4 in (70.5 m)
  • Wingspan: 195 ft 8 in (59.7 m)
  • Height: 63 ft 5 in (19.3 m)
  • Wing area: 5,500 ft² (510 m²)
  • Empty weight: 410,000 lb (190,000 kg)
  • Loaded weight: 820,000 lb (370,000 kg)
  • Powerplant: 4× General Electric CF6-50E2 turbofans, 52,500 lbf (234 kN) each


  • Maximum speed: 523 knots (602 mph, 969 km/h)
  • Range: 6,200 nm (7,100 mi, 11,000 km)
  • Service ceiling: 45,000 ft (14,000 m)
  • Wing loading: 150 lb/ft² (730 kg/m²)
  • Thrust/weight: 0.26

External links

Related content

Related development

  • Boeing 747

Comparable aircraft

  • E-10 MC2A
  • Ilyushin Il-80

Designation sequence

  • E-1 – E-2 – E-3 – E-4 – E-5 – E-6 – E-7