Boeing 737–236

Boeing 737
A Boeing 737-200, the first mass-produced 737 model, in operation with South African Airlink in 2007
Role	Narrow-body jet airliner and Business jet
National origin	United States
Manufacturer	Boeing Commercial Airplanes
First flight	April 9, 1967
Introduction	February 10, 1968, with Lufthansa
Status	In service
Primary users	Southwest Airlines Ryanair United Airlines American Airlines
Produced	1966–present
Number built	9,716 as of September 2017
Unit cost	737-100: US$32 million 737-600: US$59.4 million 737-700: US$80.6 million 737-800: US$96.0 million 737-900ER: US$101.9 million
Variants	Boeing T-43
Developed into	Boeing 737 Classic Boeing 737 Next Generation Boeing 737 MAX

The Boeing 737 is a short- to medium-range twinjet narrow-body airliner developed and manufactured by Boeing Commercial Airplanes in the United States. Originally developed as a shorter, lower-cost twin-engine airliner derived from the 707 and 727, the 737 has developed into a family of ten passenger models with capacities from 85 to 215 passengers. The 737 is Boeing's only narrow-body airliner in production, with the 737 Next Generation (-700, -800, and -900ER) and the re-engined and redesigned 737 MAX variants currently being built.

The 737 was originally envisioned in 1964. The initial 737-100 made its first flight in April 1967, and entered airline service in February 1968 at Lufthansa. Next, the lengthened 737-200 entered service in April 1968. In the 1980s, Boeing launched the longer −300, −400, and −500 models, subsequently referred to as the Boeing 737 Classic series and featuring CFM56 turbofan engines along with wing improvements.

The 737 Next Generation was introduced in the 1990s, with a redesigned, increased span laminar flow wing, upgraded "glass" cockpit, and new interior. The 737 Next Generation comprises the four −600, −700, −800, and −900 models, with lengths ranging from 102 to 138 ft (31.09 to 42.06 m). Boeing Business Jet versions of the 737 Next Generation are also produced. The 737 was revised again in the 2010s for greater efficiency, with the 737 MAX series featuring CFM International LEAP-1B engines and improved winglets. The 737 MAX entered service in 2017.

The 737 series is the best-selling jet commercial airliner in history. The 737 has been continuously manufactured by Boeing since 1967, with 9,716 aircraft delivered and 4,431 orders yet to be fulfilled as of September 2017^[update]. Assembly of the 737 is performed at the Boeing Renton Factory in Renton, Washington. Many 737s serve markets previously filled by 707, 727, 757, DC-9, and MD-80/MD-90 airliners, and the aircraft currently competes primarily with the Airbus A320 family. As of 2006, there were an average of 1,250 Boeing 737s airborne at any given time, with two departing or landing somewhere every five seconds.