The Curtiss-Wright C-46 Commando was a transport aircraft originally derived from a commercial high-altitude airliner design. It was instead used as a military transport during World War II by the United States Army Air Forces as well as the U.S. Navy/Marine Corps under the designation R5C. Known to the men who flew them as "The Whale," or the "Curtiss Calamity," the C-46 served a similar role as its counterpart, the Douglas C-47 Skytrain, but was not as extensively produced. At the time of its production, the C-46 was the largest twin-engine aircraft in the world, and the largest and heaviest twin-engine aircraft to see service in WWII. After World War II, a few surplus C-46 aircraft were briefly used in their original role as passenger airliners, but the glut of surplus C-47s dominated the marketplace with the C-46 soon relegated to primarily cargo duty. The type continued in U.S. Air Force service in a secondary role until 1968. However, the C-46 continues in operation as a rugged cargo transport for Arctic and remote locations with its service life extended into the 21st century.