The Boeing 737 is a short-range, low-wing, twin-engine, low-wing jet aircraft manufactured in the USA. The drive is provided by two Pratt and Whitney JT8D or CFM International CFM56 engines. The flight of the prototype took place in 1967, and serial production started in 1968 and is still ongoing. The Boeing 737 is the most frequently ordered passenger plane in history, and by mid-2017, as many as 9,486 copies of this aircraft had been built! The aircraft of this type was created as a response of the Boeing concern to the demand reported by American airlines for a new passenger machine characterized by low operating costs. In addition, it uses a "2x3" seating system, ie there are two rows of 3 seats in the passenger compartment, which allowed to carry a larger number of passengers. Several major development versions of this very successful aircraft were produced in the course of serial production. The first mass-produced was the Boeing 737-100, but the Boeing 737-200 model was quickly put into service, with improved performance and aerodynamic properties. The Boeing 737-600, 737-700 and 737-800 models, which appeared in the late 1990s, used the most modern avionics with a glass cockpit layout and LCD displays instead of analog clocks. One of the newest versions is the Boeing 737-900, which was flown in 2000. Its aerodynamics have been improved and the shape of the wings has been changed, thanks to which the range has improved. Depending on the version, the Boeing 737 can take 104 to 215 passengers on board.