What is the Boeing 737 MAX?

The 737 MAX was announced in 2011 as a response to the Airbus A320neo. Rather than design a new aircraft, Boeing kept the 737 Next Generation airframe and fitted it with CFM International LEAP-1B engines, larger in diameter and more efficient, split-tip winglets and updated avionics with large cockpit displays. The result, according to the manufacturer, burns 14% less fuel than the NG and reduces noise. Because the new engines did not fit under the wing in the original position, they were moved forward and raised, which changed the aircraft's behaviour at high angles of attack and led to the addition of the MCAS system.

The family has four members: the MAX 7, the shortest, with about 150 seats and greater range; the MAX 8, the best-selling version, with 162 to 210 seats and about 6,500 km (3,500 nmi) of range; the MAX 9, with up to 220 seats; and the MAX 10, the longest, for up to 230 passengers. The MAX 8 and MAX 9 have been in service since 2017 and 2018; the MAX 7 and MAX 10 were late to FAA certification due to problems with the engine anti-ice system. The MAX order backlog exceeds 4,000 aircraft (as of December 2025).

In October 2018 and March 2019, two MAX 8s operated by Lion Air and Ethiopian Airlines crashed shortly after takeoff, killing 346 people in total. Investigations pointed to MCAS, which pushed the nose down based on a single faulty angle-of-attack sensor, without pilots fully understanding the system. The model was grounded worldwide from March 2019 until late 2020, when it returned to service with redesigned software, a second reference sensor and new crew training.