The Lockheed C-5 Galaxy is an impressive military transport aircraft specifically designed to provide strategic heavy airlift over intercontinental distances. In fact, the C-5 is the largest American military transport and one of the largest military aircraft worldwide. The aircraft is capable of carrying outsize and oversize cargo which can be easily loaded through its large nose cargo door. The C-5 took to the skies for the first time on June 30, 1968, and is operated by the United States Air Force.

Back in the early 1960's, several companies began studies into a new large transportation aircraft that would replace the C-133 transport and complement C-141 Starlifters. Interesting detail was the fact that the US Army demanded an aircraft larger than the C-141. A few years later, in 1962, the US army rejected the first proposal, called the CX-4 transport, since it was not viewed as a significant advance over the original C-141. In 1963, the CX-X was presented and featured a gross weight of 550,000 lb, a maximum payload of 180,000 lb and a cruise speed of Mach 0.75 (920 km/h). It had a cargo compartment which was 100 feet (30 m) long, 13.5 feet (4.1 m) high and 17.2 feet (5.2 m) wide, and could be loaded both from the back as through the nose. Eventually, RFPs went for bid in 1964 with proposals for the aircraft being received later that same year. Manufacturers interested in producing the four-engined aircraft were Boeing, Douglas, General Dynamics, Lockheed and Martin Marietta while engine manufacturers General Electric, Curtiss-Wright Corporation, and Pratt & Whitney proposed several engine designs. A year later in 1965, Lockheed's aircraft design and General Electric's engine design were selected for the new transport.

On March 2, 1968, the first Lockheed C-5A Galaxy rolled out of the manufacturing plant in Marietta, Georgia. It took of for the first time on June 30, 1968 when Lockheed-Georgia Co. began flight testing the new C-5A Galaxy. In June 1970, the first operational Galaxy was delivered to the 437th Airlift Wing based at Charleston Air Force Base, SC

In the 1970's, the C-5 Galaxy was considered for the role of Shuttle Carrier Aircraft in order to transport the Space Shuttle to the Kennedy Space Center. Unfortunately for Lockheed, it was rejected in favor of the Boeing 747, partly due to the 747's low-wing design. Another interesting detail is the fact that the Soviet Union chose to transport its own shutlles using the Antonov An-225, which is an even bigger version of the An-124 and is similar to the C-5 design.

Lockheed encountered a set-back during the 1970's as wing cracks were discovered throughout the C-5 fleet. Consequently, the whole fleet of C-5A aircraft were restricted to a maximum of 50,000 pounds of cargo each. In order to increase its service life and lifting capability, the C-5A underwent a re-winging program during the early 1980's. In 1986 the first C-5B was delivered to Altus Air Force Base and totalled 50 by the time production ceased in April 1989. The C-5B includes all C-5A improvements as well as more than 100 additional system modifications to improve maintainability and reliability.

In 1998, the AMP, or Avionics Modernization Program, began upgrading the C-5's avionics to include a modern glass cockpit, new autopilot system and navigation equipment. Another part of the modernization program included the Reliability Enhancement and Re-engining Program, called RERP. The progam emphasized on replacing the engines with newer, more powerful ones. Furthermore, one of the C-5A's was being X-rayed and torn down, panel by panel just to see how stressed, cracked, and corroded the aircraft is. The information obtained in the tear down will be used to determine whether to give the RERP upgrade to all the C-5's or just a couple of them. At the moment, three C-5s undergo the RERP as a test with production planned to begin in May 2008.