The Douglas C-133 Cargomaster was a large cargo aircraft built between 1956 and 1961 by the Douglas Aircraft Company for use with the United States Air Force. The C-133 was the USAF's only production turboprop-powered strategic airlifter, entering service shortly after Lockheed's better known C-130 Hercules, which was known as a tactical airlifter. It provided airlift services in a wide range of applications, being replaced by the C-5 Galaxy in the early 1970s.
The C-133 was for many years the only USAF aircraft capable of hauling very large or very heavy cargo. Despite the C-124 Globemaster II's capabilities, there was much cargo that it could not carry because of its configuration with a cargo deck 13 ft (4 m) off the ground and its lower, though substantial, engine power.
By 1971, shortly before the introduction of the Lockheed C-5 Galaxy, the Cargomaster was obsolete as well as being worn out, and all were withdrawn from service in 1971. The C-133 was originally a 10,000-hour airframe that had been life-extended to 19,000 hours. Severe vibration had caused critical stress corrosion of the airframes to the point that the aircraft was beyond economical operation any longer. The Air Force managed to keep as many of the C-133 fleet in service as possible until the C-5 finally entered squadron service.
C-133s set a number of unofficial records, including records for military transport aircraft on trans-Atlantic and trans-Pacific routes. Among the longest were non-stop flights from Tachikawa AB, Japan to Travis AFB, CA (17:20 hours on 22 May 1959, 5,150 mi/8,288 km, 297.2 mph/478.3 km/h) and Hickam AFB, HI to Dover AFB, DE in about 16 hours (4,850 mi/7,805 km 303.1 mph/487.8 km/h). The only FAI officially-sanctioned record was in December 1958, when C-133A 62008 lifted a payload of 117,900 lb (53,480 kg) to an altitude of 10,000 ft (3,048 m) at Dover AFB, DE.