The Lockheed C-5M Super Galaxy is the largest military transport aircraft built for the United States Air Force and the third largest in the world (after the now-destroyed Antonov An-225 and the An-124). A total of 52 Super Galaxies remain active, with the rest in storage, scrapped, written off, or cannibalized for parts. Most flying C-5Ms are upgraded C-5Bs, although there are also some upgraded C-5As.