The Boeing 747 Jumbo Jet is a four-engine, wide-body, long-range, low-wing passenger aircraft in the American low-wing configuration. Propulsion is provided by four Pratt and Whitney JT9D or PW4000 or Rolls-Royce RB211 or General Electric CF6 or GEnx engines. The prototype flew in 1969 and serial production began in 1970 and is still ongoing. As of April 2017, 1,531 Boeing 747s had been produced. Airplanes of this type are characterized by two passenger decks, which significantly increased the number of passengers - depending on the version - from 366 to 568! Many significant development versions of this very successful aircraft were built during serial production. The first mass-produced aircraft was the Boeing 747-100, but the Boeing 747-200 model quickly entered service, with improved performance and improved flight range. Later, the 747-400 version was offered, which proved to be the most popular of all produced. It was characterized by improved aerodynamic properties and increased passenger cabin capacity