Boeing E-4

Two of the original 747-200 airframes were originally planned to be commercial airliners. When the airline did not complete the order, Boeing offered the airframes to the United States Air Force, as part of a package leading to a replacement for the older EC-135J National Emergency Airborne Command Post (NEACP). Under the 481B NEACP program the Air Force Electronic Systems Division awarded Boeing a contract in February 1973 for two unequipped aircraft, designated E-4A, powered by four P&W JT9D engines, to which a third aircraft was added in July 1973. (EMP) simulator for testing. In December 1973, a fourth aircraft was ordered. It was fitted with more advanced equipment, resulting in the designation E-4B. On 21 December 1979, Boeing delivered the first E-4B, AF Serial Number 75-0125, In November 1973, it was reported that the program cost was estimated to total $548 million, equivalent to $ billion in for a planned seven 747s, with six as operational command posts and one more for research and development. In addition to the purchase and upgrade costs, the E-4 costs nearly $160,000 per hour, , for the Air Force to operate. The E-4B fleet had an estimated unit cost of approximately US$223.2 million each in 2024. ==Design==

of Travis AFB in preparation for aerial refueling The E-4B is designed to survive an EMP with systems intact, and has state-of-the-art direct fire countermeasures. Many older aircraft have been upgraded with glass cockpits. The E-4B still uses traditional analog flight instruments, as they are less susceptible to damage from an EMP blast. The E-4B is capable of operating with a crew up to 112 people, including flight and mission personnel, the largest crew of any aircraft in US Air Force history. With in-flight aerial 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 is designed to be able to remain airborne for a full week in the event of an emergency. It takes two fully loaded KC-135 tankers to fully refuel an E-4B. The E-4B has three operational decks: upper, middle, and lower. Middle deck The middle deck contains the conference room, which provides a secure area for conferences and briefings. It contains a conference table for nine people. Aft of the conference room is a projection room serving the conference room and the briefing room. The projection room had the capability of projecting computer graphics, overhead transparencies, or 35 mm slides to the conference room and/or the briefing room, and has since been modernized with flat screen displays. and is used for religious ceremonies. 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, two convection ovens, and a microwave oven to give stewards the capability to provide more than 100 hot meals during prolonged missions. Four seats are located on the left side of the forward entry area for the secret service and the stewards. Behind the forward entry area, is the National Command Authority (NCA) area, which is designed and furnished as an executive suite. It contains an office, a lounge, a sleeping area, and a dressing room. Telephone instruments in this area provide the NCA with secure and clear worldwide communications. The briefing room contains a briefing table with three executive seats, 18 additional seats, a lectern, and two 80-inch flat screen LED monitors flush mounted to the partition. 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. Lower deck 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. An AC/DC powered hydraulic retractable airstair is located in the forward right side of the forward lower equipment area, installed for airplane entry and exit. In the event of an emergency, the airstair can be jettisoned. The aft lower lobe contains the maintenance console and mission specific equipment. The lower trailing wire antenna (TWA) area contains the aircraft's 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 Ohio-class ballistic missile submarines, is particularly effective in picking up EMP. The flight avionics area contains the aircraft systems power panels, flight avionics equipment, liquid oxygen converters, and storage for baggage and spare parts. ==Operational history==

in Bogotá, Colombia The E-4 fleet was originally deployed in 1974, The E-4 was also capable of operating the "Looking Glass" missions of the Strategic Air Command (SAC). The aircraft were originally stationed at Andrews Air Force Base, Maryland, so that the U.S. president and secretary of defense could access them quickly in the event of an emergency. The name "Nightwatch" originates from the richly detailed Rembrandt painting, The Night Watch, that depicts local townsfolk protecting a town. It 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. The NEACP aircraft originally used the static call sign "Silver Dollar". This call sign faded from use when daily call signs were put in use. The E-4B serves as the Secretary of Defense's preferred means of transportation when traveling outside the U.S. 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. With the adoption of two highly modified Boeing 747-200Bs, Air Force designation VC-25A, 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 (FEMA) crews to natural disaster sites and serving as a temporary command post on the ground, until facilities could be built on site. 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. at Defence Establishment Fairbairn, Canberra, Australia during bilateral defense talks, February 2008 One E-4B is kept on alert at all times. The "cocked" or "on alert" E-4B is crewed 24 hours a day with the 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. In his book Black Ice, Dan Verton identifies this aircraft as an E-4B taking part in an operational exercise, and the exercise was canceled when the first plane struck the World Trade Center. Air traffic control recordings and radar data indicate this E-4B call sign VENUS77 became airborne just before 9:44 am, circled north of the White House during its climb, and then tracked to the south of Washington, D.C., where it entered a holding pattern. In 2008, Brent Scowcroft explained that he was on this plane to go on an inspection tour to one unspecified nuclear weapons site, as chairman of a DoD team called "End to End review". In January 2006, Secretary of Defense Donald Rumsfeld announced a plan to retire the entire E-4B fleet starting in 2009. This was reduced to retiring one of the aircraft in February 2007. Rumsfeld's successor, Robert Gates, reversed this decision in May 2007. In the 2015 federal budget there were no plans for retiring the E-4B. The E-4B airframe has a usable life of 115,000 hours and 30,000 cycles, which would be reached in 2039. The maintenance limiting point would occur sometime in the 2020s. All four produced are operated by the U.S. Air Force, and are assigned to the 1st Airborne Command Control Squadron (1ACCS), of the 595th Command and Control Group at Offutt Air Force Base, Nebraska. Operations are coordinated by the United States Strategic Command. When the President travels outside of North America using a VC-25A as Air Force One, an E-4B will deploy to a second airport in the vicinity of the President's destination, to be readily available in the event of a world crisis or an emergency that renders the VC-25A unusable. When President Barack Obama visited Honolulu, Hawaii, an E-4B was often stationed 200 miles away at Hilo International Airport on Hawaii Island. In June 2017, two of the aircraft were damaged by a tornado that struck Offutt AFB, hit by falling debris after the tornado damaged the hangar the aircraft were stationed in. They were out of service for 11 weeks while repairs took place. The E-4B aircraft have been based at the nearby Lincoln Air National Guard Base three times: in 2006, in 2019 during the Missouri flood, and 2021–22 subsequent runway replacement. Replacement In 2021 and 2022, the U.S. Air Force began developing a replacement for the E-4. The new platform is currently known as the Survivable Airborne Operations Center. This aircraft is to be developed by Sierra Nevada Corporation collaborating with Rolls Royce, based on the Boeing 747-8I. ==Operators==

; • United States Air Force – Global Strike Command • 595th Command and Control Group – Offutt AFB, Nebraska • 1st Airborne Command and Control Squadron ==Variants==

;E-4A: Three aircraft produced (s/n 73-1676, 73-1677, and 74-0787), powered by Pratt & Whitney JT9D-7A (first two aircraft) or General Electric CF6-50E2 (third aircraft) turbofan engines. No bulge to house equipment on top of fuselage. These were later converted to E-4Bs. ;E-4C: Five Boeing 747-8I airliners purchased from Korean Air for conversion into replacement platforms for existing NAOC aircraft. ==Specifications (E-4B)==

==Notable appearances in media==

The E-4B plays a prominent role in two motion pictures. In the 1990 HBO film ''By Dawn's Early Light'', following a nuclear strike by the Soviets, the aircraft serves as a flying platform for the presumed president, the ex–Secretary of the Interior, who is played by Darren McGavin. The aircraft is pursued by a Boeing EC-135 "Looking Glass", which successfully intercepts it. In the 2002 motion picture The Sum of All Fears, the president and his staff travel on an E-4B, following the detonation of a nuclear weapon by terrorists. In the novel, the Vice President and his family are aboard the NEACP after terrorists detonate a nuclear bomb in Denver, while the President and his National Security Advisor are stuck at Camp David during a blinding snowstorm. National Geographic produced a television special on doomsday planning of the U.S., which includes footage from inside an E-4B during a drill. ==See also==