The Lockheed C-5 Galaxy was the largest landplane ever built at the time of its first flight. It was born out of the USAF's MATS requirement for a large strategic transport and was unique in having an upward-hingeing nose in addition to a rear-loading ramp thus allowing it to carry a myriad of vehicles and weapons including main battle tanks and ballistic missiles. Otherwise, the C-5 had the high-set swept wing and prominent T-tail which is characteristic of most US large transports like the C-141 albeit on a much larger scale which also required a massive 28-wheel landing gear. But despite its size, the C-5 is capable of operating on semi-prepared runways making it ideal for quick deployment of troops and equipment to war zones, and by separating its pressurized and air-conditioned cargo hold into decks, can carry both simultaneously (up to 345 fully equipped troops can be transported). Although it has since been eclipsed in size by the massive Soviet An-124, the C-5 remains in widespread use by the USAF and Air National Guard and will continue to be in action for the conceivable future.

The first C-5A was flown on 30 June 1968 and entered service in 1970 with the Military Airlift Command (MAC) where they were immediately flown to Europe and the Far East. Inflight-refuelling and a number of other additions were incorporated leading up to the C-5B which also included more powerful engines. A major modernization program is currently underway to increase the service life of existing C-5A and C-5B while at the same time providing new engines and upgrading their avionics (including a new autopilot system) to GATM compliance.