Boeing 737-900

The 737-900 topped the 737 Next Generation range, the third generation of the airliner, launched in November 1993 to compete with the Airbus A320 family with a new wing, CFM56-7 engines and a glass cockpit. The Next Generation took shape after regular Boeing customer United Airlines bought the fly-by-wire A320: Boeing began work on an updated series in 1991 and announced it on November 17, 1993, and the wing, engine and fuel-capacity improvements extended the 737's range by 900 nautical miles (1,700 km) to over 3,000 nmi (5,600 km). Within that family, which covered 108 to 215 seats, the -900 was the high-capacity answer. Alaska Airlines launched the variant in November 1997; development began on September 10, 1997, with an order for ten aircraft from that airline.

It was a 737-800 stretched to 138 ft 2 in (42.11 m). Its fuselage was longer even than that of the Boeing 707 and its capacity came close to that of the 757-200. However, the -900 retained the maximum takeoff weight, fuel capacity and emergency exit configuration of the -800, and that last choice defined it: with no additional doors, certification limited the cabin to 189 seats in a single class, while a typical two-class layout seated about 177 (179 in some layouts). In effect it traded range for capacity, with a range of about 5000 km. For multi-class layouts the limit was not a problem, but it made the aircraft less attractive against the Airbus A321, which it never managed to challenge effectively.

The 737-900 first flew on August 3, 2000, and Alaska Airlines accepted the first delivery on May 15, 2001. It was presented in 2001 as the longest version yet. As a marketing exercise for the then-new 787 Dreamliner, Boeing delivered a -900 to Lion Air in Dreamliner colors, as it did with a -700 for Air Berlin and a -800 for Ryanair; the aircraft were later repainted in their fleet liveries.

The type proved unpopular and only 52 were delivered; it was cancelled on October 18, 2005. Several airlines had asked early on for the seating limit to be removed and for more range, and the answer was the 737-900ER, called the 737-900X before its launch in July 2005. With an additional pair of exit doors and a flat rear pressure bulkhead, the -900ER could seat up to 220 passengers; with auxiliary fuel tanks and standard winglets it matched the range of the other NG variants, and its launch customer, Lion Air, received the first on April 27, 2007. The -900ER partly filled the gap left by the end of the 757-200, something the -900 had not achieved. The difference in success was stark: Boeing delivered all 52 737-900s ordered against 505 737-900ERs.

The -900s kept flying with the family's later improvements: from 2015 they could be fitted with Aviation Partners Split Scimitar winglets, which save up to 5.5% fuel compared with 3.3% for the blended winglets. In the fourth generation the 737 MAX 9 replaced the 737-900, and the longest NG business jet, the BBJ3, was based on the -900ER rather than the original -900.