The modernization of the aircraft, which had entered service in 1970, was performed under the Air Force's Avionics Modernization Program and included replacing analog systems with digital systems, installing a new autopilot, a new communications suite, flat-panel displays and enhanced navigation and safety system systems.
Work on the aircraft by a Lockheed Martin team took place at Travis Air Force Base in California and involved a massive rewiring of the C-5.
Lockheed said there were three aircraft being modernized at any one time during the project, which is only the first of two phases to update the C-5, which has a payload capacity of about 270,000 pounds and a flying range of as much as 2,700-plus miles with a high payload weight.
The next stage of the modernization effort is the Reliability Enhancement and Re-engining Program. In this phase, the C-5 airframe and systems will receive more than 70 enhancements.