US E 4 75 0125 EBBR Brussels 14Jun21 Carlos Geurts file info 640Korean Air sells five Boeing 747s to Sierra Nevada

Sierra Nevada Corporation (SNC) recently won a USD 13 billion contract from the USAF to develop a successor to the E-4B Nightwatch, known as the “Doomsday” plane due to its ability to survive a nuclear war and act as a command and control center during emergencies.

On 8 May 2024, Korean Air announced that they will sell five of its Boeing 747-8s to Sierra Nevada. The current E-4B aircraft, in service since the 1970s, are modified Boeing 747-200s. The sale, valued USD 674 million, aligns with Korean Air’s medium- to long-term plan to dispose of older aircraft and replace them with newer-generation ones, according to the Korean Air filing.

The aircraft, built around 2015, will be about 15 years old when the first ones enter USAF service. The specific tail numbers have not been disclosed, but most of the late-model 747-8s owned by Korean Air have been parked for at least two of the last five years due to the COVID pandemic.

It is unclear if SNC will build five Survivable Airborne Operations Center (SAOC) aircraft or replace the existing fleet of four Nightwatch 747s on a one-for-one basis and use the fifth airplane for engineering mockup, fit, and installation checks. The USAF had said it might buy up to ten Nightwatch aircraft.

US SNC Korean Air B747 HL7630 credit Jeahyun Jeon 640SNC will conduct at least some of the conversion work in Dayton, Ohio, where it has a hangar sized to accommodate 747-8s. The aircraft will be delivered to SNC by the third quarter of 2025, with fully operational SAOC aircraft scheduled for delivery by 2036. The first Korean Air Boeing 747-8B5, HL7630 (c/n 40905/1506), was delivered to Dayton (OH) on 4 June 2024.

The E-4B National Airborne Operations Center (NAOC)—known as “Nightwatch” or the “Doomsday plane”—is the USAF’s fleet of flying command posts, capable of commanding and controlling US nuclear and conventional forces. These aircraft date back to the late 1970s and early 1980s and suffer from parts obsolescence, deteriorating reliability, and "vanishing vendor" syndrome. An E-4B usually transports the Secretary of Defence and his staff on long trips, but this mission has frequently shifted to other aircraft as the E-4B’s availability has declined. The Air Force’s most recent data indicates the E-4B’s mission availability is just over 55 percent.

The Air Force has stated it is comfortable using a “Commercial Derivative Aircraft” for the requirement, one that will be “hardened and modified to meet military requirements.” The amount of communications and other gear required for the mission necessitates a large, four-engined aircraft, but both Airbus and Boeing have stopped building new A380 and 747 aircraft, respectively. This required SNC to buy secondhand aircraft.

The following E-4B Nightwatch aircraft are operated by the 1st Airborne Command Control Squadron First is First, part of the 595th Command and Control Group, at Offutt AFB (NE): 73-1676, 73-1677, 74-0787 and 75-0125

Credit photos: Carlos Geurts (Scramble Archive) and Jeahyun Jeon (via

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