Length: 12"
Code: NC10158

Based on a recent study showing 80% of the C-5 airframe service life remaining,  AMC began an aggressive program to modernize all remaining C-5Bs and C-5Cs and many of the C-5As. The C-5 Avionics Modernization Program (AMP) began in 1998 and includes upgrading avionics to Global Air Traffic Management compliance, improving communications, new flat panel displays, improving navigation and safety equipment, and installing a new autopilot system. The first flight of the first modified C-5 with AMP (85-0004) occurred on 21 December 2002.

Another part of the plan is a comprehensive Reliability Enhancement and Re-engining Program (RERP), which includes new General Electric CF6-80C2 engines, pylons and auxiliary power units, with upgrades to aircraft skin and frame, landing gear, cockpit and the pressurization system. The CF6 engine produces 22% more thrust (for 50,000 lbf/220 kN total from each engine) than existing C-5 engines, which will result in a 30% shorter take-off roll, a 38% higher climb rate to initial altitude, a significantly increased cargo load, and a longer range between refueling.The C-5s that complete these upgrades are designated C-5M Super Galaxy.

The C-5 AMP and RERP modernization programs plan to raise mission-capable rate to a minimum goal of 75%. Over the next 40 years, the U.S. Air Force estimates the C-5M will save over $20 billion. The first C-5M conversion was completed on 16 May 2006, and performed its first flight on 19 June 2006. C-5Ms have been in flight testing out of Dobbins Air Reserve Base since June 2006. Test aircraft include a distinctively colored nose boom to acquire flight data.

The USAF decided to convert remaining C-5Bs and C-5Cs into C-5Ms with avionics upgrades and re-engining in February 2008. The C-5As will receive only the avionics upgrades.The three test C-5Ms successfully completed developmental flight testing in August 2008. The test aircraft will begin Operational Test and Evaluation in September 2009. The RERP upgrade program is to be completed in 2016.

Lockheed Martin announced that a C-5M test flight on 13 September 2009, set 41 new records. The flight's data have been submitted to the National Aeronautic Association for formal acceptance. The C-5M carried a payload of 176,610 lb (80,110 kg) to over 41,100 ft (12,500 m) in 23 minutes, 59 seconds. The flight set 33 time to climb records at various payload classes, and broke the world record for greatest payload to 6,562 feet (2,000 meters). The aircraft used for this flight had a takeoff weight of 649,680 lb (294,690 kg), which included payload, fuel and crew.