Boeing E-6 Mercury

The Boeing E-6 Mercury (formerly E-6 Hermes) is an airborne command post and communications relay based on the Boeing 707-320. The original E-6A manufactured by Boeing's defense division entered service with the United States Navy in July 1989, replacing the EC-130Q. It conveyed instructions from the National Command Authority to fleet ballistic missile submarines (see communication with submarines), a mission known as TACAMO (TAke Charge And Move Out). The E-6B model deployed in October 1998 kept this role, but added further command post capabilities and control of land-based missiles and nuclear-armed strategic bombers. The E-6B replaced Air Force EC-135Cs in the "Looking Glass" role, providing command and control of U.S. nuclear forces should ground-based control become inoperable. With production lasting until 1991, the E-6 was the final derivative of the Boeing 707 to be built.

Design and development

Like the E-3 Sentry airborne warning and control system (AWACS) aircraft, the E-6 is adapted from Boeing's 707-320 airliner. The first E-6 made its maiden flight from Boeing's Renton Factory on 19 February 1987, when it was flown to Boeing Field, Seattle, for fitment of mission avionics, being delivered to the Navy for testing on 22 July 1988. The E-6A, which was initially named Hermes, entered service with VQ-3 on 3 August 1989, with the second squadron, VQ-4 receiving its first E-6As in January 1991, allowing the EC-130Q to be phased on in June that year. The E-6A was renamed Mercury in autumn 1991 by request of the US Navy. Sixteen were delivered up to 1992.