Assembled on the same production line as the E-3 Sentry Airborne Warning and Control System (AWACS) aircraft, was the E-6 Mercury, TACAMO ("Take Charge and Move Out") aircraft, also based on the Boeing 707 airframe.
The U.S. Navy awarded Boeing a full-scale development contract for the E-6A in 1983, and the prototype E-6A rolled out from the Renton, Wash., factory in December 1986.
First flight was in February 1987. Delivery of the first production aircraft was in August 1989, with delivery of the final airplane in May 1992.
Boeing delivered a total of 16 E-6 "survivable airborne communication system" airplanes to the Navy from 1989 to 1992.
The TACAMO airplanes support the Navy's ballistic missile submarine force, providing a vital link to the force from national command authorities. The TACAMO E-6B airplanes are equipped with dual trailing wires that serve as transmitter and antenna, transmitting in the very low frequency spectrum.