The Lockheed C-5 Galaxy is a military transport aircraft, the largest in the American military and one of the largest in the world. It was designed to carry outsize and oversize cargo, providing strategic heavy airlift over intercontinental distances. Operated by the United States Air Force (USAF), it is one of the physically largest aircraft in the world that is capable of flying on a regular basis.

In 1964, design proposals for a heavy jet transport were submitted by various companies in response to a US Army requirement. The new aircraft was set to replace the Douglas C-133 Cargomaster and complement the Lockheed C-141 Starlifter. In 1965, Lockheed's aircraft design and General Electric's engine design were selected. The first C-5A Galaxy rolled out of the manufacturing plant on March 2, 1968 and the aircraft's maiden flight was on June 30. The first operational Galaxy was delivered in June 1970. The C-5 has a distinctive high T-tail and is similar in appearance to its smaller sister transport the C-141. It is equipped for aerial refueling, giving it an extended range. Nose and aft doors permit “drive-through” loading and unloading of cargo. The Galaxy is capable of carrying nearly all of the Army's combat equipment, including the 74-ton armored vehicle launched bridge, from the United States to any location in the world.

In the early 1970s, the C-5 was considered by NASA for the role of Shuttle Carrier Aircraft, which was tasked to transport the Space Shuttle to Kennedy Space Center. However, the Boeing 747 was chosen instead due in part to its low-wing design. From 1981 to 1987, 77 C-5As underwent a re-winging program to increase their lifting capability and service life after wing cracks were found throughout the fleet. The redesigned wings were made of a new aluminum alloy that did not exist during the original production