The twin-engine DC-3, developed by Douglas Aircraft business, during the mid-30s, can be explained as a real milestone in history of civil aviation. Its low-wing configuration, the good machines while the excellent performance makes it one of many transport aircraft ever made and a real revolution in the flight industry. In civil aviation, many commercial operators and air companies used the United states twin-engine to do quick and moderate range routes. For instance, Swissair, the national flight of Switzerland, used in the late '40s plus in the '50s, the Dakota. Soon the aircraft is appreciate the high reliability, the reduced running expenses as well as the good loading capability.