The original E-6A manufactured by Boeing's defense division entered service with the United States Navy in July 1989, replacing the EC-130Q.

[1] Like the E-3 Sentry Airborne Warning and Control System aircraft, the E-6 is adapted from Boeing's 707-320 airliner.

This greatly increases the situational awareness of the pilot and saves significant cost over the previous custom avionics package.

The term "Looking Glass" is used because the ABNCP "mirrors" the abilities of the US Strategic Command GOC to control nuclear forces.

[8] In 2021, one of the E-3D Sentry aircraft that had been in service with the Royal Air Force was purchased for conversion into a dedicated E-6 trainer.

The Air Force independently pursued an E-4 replacement under the Survivable Airborne Operations Center program.

[12] Data from Jane's all the world's aircraft, 1992–93[13] The US Navy – Fact File: E-6B Mercury Airborne Command Post[14]General characteristics Performance Avionics