It is now maintained and upgraded by Lockheeds successor, Lockheed Martin. It provides the United States Air Force (USAF) with a heavy intercontinental-range strategic airlift capability, one that can carry outsized and oversized loads, including all air-certifiable cargo. The Galaxy has many similarities to the smaller Lockheed C-141 Starlifter and the later Boeing C-17 Globemaster III. The C-5 is among the largest military aircraft in the world. The C-5 is a large, high-wing cargo aircraft with a distinctive high T-tail fin (vertical) stabilizer, with four TF39 turbofan engines mounted on pylons beneath wings that are swept 25°. (The C-5M uses newer GE CF6 engines.) Similar in layout to its smaller predecessor, the C-141 Starlifter, the C-5 has 12 internal wing tanks and is equipped for aerial refueling. Above the plane-length cargo deck is an upper deck for flight operations and for seating 80 passengers in rear facing seats (unlike most commercial airplanes) and the embarked loadmaster crew in forward facing seats. Bay doors at both nose and tail open to enable "drive-through" loading and unloading of cargo. For further details of the development and design, plus the five variants, click here. Specifications below are for the upgraded C-5M model.