Boeing 737-900ER

The 737-900ER (Extended Range) was the final and largest version of the 737 Next Generation. It came to correct a misstep. Its predecessor, the 737-900, launched by Alaska Airlines in November 1997, had stretched the fuselage to 138 ft 2 in (42.11 m) but kept the same exit configuration as the -800, which limited seating to 189 (about 177 in two classes), as well as the same maximum takeoff weight and fuel capacity, trading range for payload. It first flew on August 3, 2000 and Alaska accepted the first one on May 15, 2001, but it proved unpopular: only 52 were delivered before it was replaced by the -900ER.

Before launch it was called the 737-900X. Boeing designed it with three goals: to fill the range and capacity gap left in its product line by the end of 757-200 production, which had ceased in 2004, to address the shortcomings of the -900 and to compete directly with the Airbus A321. For range it used up to two auxiliary fuel tanks in the cargo hold and standard winglets, which brought the stretched jet up to the range of the other NG variants. For capacity it added an extra pair of exit doors and a flat rear pressure bulkhead, raising maximum seating to 220 passengers in a single class, or about 180 in two classes. Airlines may deactivate the extra exits with plugs if the cabin has 189 seats or fewer, the same arrangement later inherited by its successor, the 737 MAX 9. The Short Field Performance package, optional on the rest of the NG family, was standard equipment on the -900ER. Born in 2004 of the needs of Gol Transportes Aéreos, which frequently operated from restricted airports, it improved takeoff and landing performance and allowed more payload or fuel on runways under 5,000 feet (1,500 m); on the -800 and -900ER landing payloads rose by up to 8,000 lb and takeoff payloads by up to 2,000 lb. Like all NGs it was powered by CFM International CFM56-7B engines.

The programme was launched in July 2005 and the aircraft first flew in September 2006. The first example was delivered on April 27, 2007 to the Indonesian low-cost carrier Lion Air, the launch customer, in a special dual paint scheme combining Lion Air's logo on the tail with Boeing's livery colours on the fuselage. With the -900ER Boeing again had an answer for the high-demand routes previously flown by the 757 and for airlines weighing its catalogue against the A321.

The type kept receiving improvements during production. In 2014 the Split Scimitar winglets from Aviation Partners, resembling those of the 737 MAX, became available for the -900ER, saving up to 5.5% fuel against 3.3% for the earlier blended winglets. Its airframe was also the basis of the BBJ3 version of the Boeing Business Jet: 1,120 square feet (104 m²) of cabin floor, 35% more interior space and 89% more luggage space than the BBJ2, an auxiliary fuel system for a range of up to 4,725 nmi (8,751 km) and a head-up display. The first was completed in August 2008.

In all, 505 737-900ERs were delivered, against 52 of the original -900. Boeing stopped assembling passenger NGs in 2019 and delivered the last two to China Eastern Airlines on January 5, 2020. In the MAX family, the role of the -900 and -900ER passes to the 737 MAX 9, which succeeds the -900ER, one of the most widely used variants of the NG generation; since 2020 its official FAA type certificate designation has been 737-9.