Boeing 737 MAX 8

The 737 MAX 8 was the first variant of the fourth-generation 737 and the replacement for the 737-800. The programme was a response to the Airbus A320neo family, launched in December 2010, which by July 2011 had broken Boeing's monopoly at American Airlines with an order for 130 aircraft. On July 20, 2011, Boeing announced plans for a new 737 generation powered by the CFM LEAP-1B, with American Airlines intending to order 100, and on August 30, 2011, it confirmed the launch of the 737 MAX. The aim was to re-engine the NG with very high bypass ratio engines, aerodynamic improvements, most notably split-tip winglets, and airframe modifications. Boeing completed the firm configuration of the MAX 8 on July 23, 2013.

To keep sufficient ground clearance, the MAX uses new engine mounts and pylons that place the LEAP engines higher and further forward than the CFM56s of earlier generations. The new winglet, 9 feet 6 inches (2.90 m) tall, resembles a hybrid of a blended winglet, wingtip fence and raked wingtip; a MAX 8 with 162 passengers on a 3,000-nautical-mile (5,600 km) flight was projected to burn 1.8% less fuel than a blended-winglet aircraft.

On August 13, 2015, the first 737 MAX fuselage completed assembly at Spirit AeroSystems in Wichita, Kansas, for a test aircraft later destined for Southwest Airlines. On December 8, 2015, the first 737 MAX, a MAX 8 named Spirit of Renton, was rolled out at the Renton factory, and on January 29, 2016, it made the type's first flight from Renton Municipal Airport, nearly 49 years after the maiden flight of the 737-100. Four test aircraft shared the work: 1A001 flew aerodynamic trials of flutter, stability and control and takeoff performance; 1A002 performance and engine testing, noise, cold weather, high altitude and fuel burn; 1A003 aircraft systems including autoland; and 1A004, with an airliner layout, 300 hours of function-and-reliability flying.

The FAA certified the MAX 8 on March 8, 2017, and EASA approved it on March 27, 2017. After the test hours and ETOPS testing, CFM International notified Boeing of a possible manufacturing quality issue with low pressure turbine discs in LEAP-1B engines, and Boeing suspended flights from May 4 to May 12. The first delivery was made on May 16, 2017, to Malindo Air (now Batik Air Malaysia), which put it into service on May 22. Norwegian Air International was the second airline to introduce the type, flying a transatlantic service on July 15, 2017, between Edinburgh and Bradley International Airport in Connecticut with a MAX 8 named Sir Freddie Laker.

The MAX 8 has a high-density version, the MAX 200, launched in September 2014 with an extra pair of exit doors and up to 200 seats in a single class; Ryanair ordered 135 and the first one flew from Renton on January 13, 2019.

The model's history was marked by two fatal 737 MAX accidents: Lion Air Flight 610 on October 29, 2018, and Ethiopian Airlines Flight 302 on March 10, 2019, in which a total of 346 people died. China was the first authority to ground the aircraft, and the FAA did so on March 13, 2019. Both crashes involved MCAS, the Maneuvering Characteristics Augmentation System, which activated on erroneous data from a single angle-of-attack sensor and applied nose-down trim; investigations found that Boeing had not fully informed operators and identified shortcomings in the FAA's certification process. During the twenty-month grounding Boeing redesigned the computer architecture behind MCAS, and the FAA cleared the type to return to service on November 18, 2020. Brazil's Gol was the first airline to resume passenger flights, on December 9, 2020, followed in the United States by American Airlines on December 29.

Despite all this, the MAX 8 is the most-ordered variant of the MAX family. It typically seats 178 passengers in two classes, up to 189 in a single class, with a range of 3,500 nautical miles.