What is the Boeing 737?

The Boeing 737 was born in the mid-1960s as a response to the Douglas DC-9 and the success of short- and medium-haul twin-engine jets. It first flew in April 1967 and entered commercial service in 1968 with Lufthansa. Since then it has gone through four distinct generations — Original, Classic, Next Generation (NG) and MAX — each with updated engines, avionics and aerodynamics, but keeping the same narrow fuselage and much of the original architecture, which allows airlines to carry pilot training and maintenance procedures over between generations. In total more than 11,000 units have been delivered: for decades it was the most-delivered commercial aircraft in history, until Airbus's A320 family overtook it in cumulative deliveries in early 2024 (as of September 2026). Today it remains the backbone of low-cost and legacy airlines alike, from Ryanair to Southwest Airlines.

The current generation, the 737 MAX, entered service in 2017 with larger, more efficient engines that forced a change in their position on the wing, which in turn altered the aircraft's aerodynamic behavior in certain maneuvers. Boeing compensated for that change with a flight control system, the MCAS, whose malfunction contributed to the Lion Air accident in 2018 and the Ethiopian Airlines accident in 2019, with 346 fatalities in total, and led the global MAX fleet to remain grounded from March 2019 until late 2020, when civil aviation authorities approved its return to service after the system was redesigned.