Boeing E-6 Mercury

Like the E-3 Sentry Airborne Warning and Control System aircraft, the E-6 is adapted from Boeing's 707-320 airliner. Rolled out at Boeing's Renton Factory in December 1986, the first E-6 made its maiden flight in February 1987, when it was flown to nearby Boeing Field in south Seattle for fitting of mission avionics. In July 1988, it was delivered to the Navy for testing. The E-6B is an upgrade of the E-6A. It includes a battle staff area and updated mission equipment. The flight deck systems were later replaced with a better, cheaper off-the-shelf 737 Next Generation cockpit. The first E-6B was accepted in December 1997. All 16 E-6A aircraft were modified to the E-6B standard, with the final delivery taking place in December 2006. Unlike most Navy aircraft that use the probe-and-drogue in-flight refueling method, the E-6 has a flying boom receptacle on the upper-forward fuselage so it can be refueled by the U.S. Air Force’s larger tanker fleet of KC-135 Stratotankers and KC-46 Pegasuses. ==Operational history==

Codenamed Looking Glass, the E-6 is United States Strategic Command's (USSTRATCOM) Airborne Command Post (ABNCP). It is designed to take over should the Global Operations Center at Offutt Air Force Base, Nebraska be incapable of communicating with nuclear forces. The term "Looking Glass” reflects the way the ABNCP "mirrors" the GOC's abilities. In August 1989, the E-6A, initially named Hermes, entered service with squadron VQ-3. In January 1991, a second squadron, VQ-4, received its first E-6As, allowing the EC-130Q to be phased out in June 1991. In autumn 1991, the E-6A was renamed Mercury at the Navy's request. Sixteen E-6A planes were delivered from 1988 to 1992. The E-6 fleet is based at Tinker Air Force Base, Oklahoma, and operated by Fleet Air Reconnaissance Squadron 3 (VQ-3), VQ-4, and VQ-7. In 2021, one of the E-3D Sentry aircraft in service with the Royal Air Force was purchased for conversion into a dedicated E-6 trainer. This was done to extend the life of the operational fleet by reducing the need for E-6s to be used for training missions. In May 2025, the project was canceled, and a new contract was issued to Northrop Grumman for the salvage of spare parts and eventual scrapping of the airframe. Replacement In 2015, both the Air Force and Navy realised that they needed new aircraft to serve the missions of both the E-4 and the E-6. At one point, they considered building one plane to replace both aircraft. In 2020, the Navy developed an aircraft specifically for the TACAMO mission, under the E-XX TACAMO program. The Air Force independently pursued an E-4 replacement under the Survivable Airborne Operations Center program. The Navy selected a variant of the Lockheed EC-130J, derived from the lengthened C-130J-30. In late 2020, initial orders were placed, with development beginning in earnest in 2022. Delivery of the first aircraft is expected in FY26. The Navy expects the E-6 to fulfill the TACAMO role into the 2030s as the E-XX is transitioned into service. In October 2024, the replacement aircraft was officially named E-130J. ==Specifications (E-6B)==