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. This platform, now modified to the E-6B standard, conveys 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). Here is the Deadliest Aircraft the United States Of America Ever Built