Boeing later introduced the 737-900, the longest variant to date. Because the -900 retains the same exit configuration of the -800, seating capacity is limited to 177 seats in two classes, or 189 in a single-class layout. Alaska Airlines launched the 737-900 in 1997 and accepted delivery on 15 May 2001. The 737-900 also retains the MTOW and fuel capacity of the -800, trading range for payload. These shortcomings until recently prevented the 737-900 from effectively competing with the Airbus A321.
