The Boeing 737 is a family of airliner built by the company Boeing since 1965. It is a twin-engine, single-aisle, short to medium-haul aircraft. It made its first flight on April 9, 1967. There are four generations of Boeing 737. Its main competitor today is the Airbus A320. It has been the most sold aircraft in the world, with more than 13,000 orders and more than 9,000 deliveries in April 2016.
The design of the Boeing 737-400 was launched in 1985 to bridge the gap between the 737-300 and the 757-200. This aircraft was also built to compete with the Airbus A320 and the McDonnell Douglas MD-80.
The Boeing B737-400 is the second version of the second-generation Boeing 737 family. More modern, longer, and larger, this version was built from 1984 until 2000. This aircraft is 3.45 meters longer than its predecessor, and the 737-300 and can carry up to 189 passengers, depending on the configuration.
The major improvement of the B737-400 is the installation of CFM56-3 engines, which are more modern and much more economical. In addition, the B737-400 includes a rear bumper process to prevent possible scratches on the aircraft’s tail during take-off, as well as a reinforced wing spar.
The prototype was deployed on January 26, 1988, and flew for the first time on February 19, 1989. The aircraft entered service on September 15, 1988, thanks to the debut of Piedmont Airlines (25 aircraft ordered).
The B737-400 also has a cargo version, the Boeing B737-400F. Boeing has also built a full-business version, the BBJ, Boeing Business Jet, which are totally custom-built.
Alaska Airlines was the first company to convert one of their 400s of regular service into an aircraft with the ability to handle ten pallets. The airline also converted five more aircraft by combining passengers and cargo. They are now operational.