Which airline received the first Boeing 737-900ER?

Lion Air received the first Boeing 737-900ER in 2007.

The 737-900ER was the highest-capacity member of Boeing’s 737 Next Generation family. Boeing created it by combining the longer fuselage of the 737-900 with features such as an additional pair of exit doors, a flat rear pressure bulkhead, and optional auxiliary fuel tanks.

Lion Air, an Indonesian airline, became the launch customer and accepted the first aircraft in April 2007. The type was particularly useful for airlines seeking more seats than a 737-800 could provide while retaining the operating characteristics of the 737 family.

The 737-900ER was later marketed widely and became the direct predecessor of the 737 MAX 9 in Boeing’s single-aisle product line. It is distinct from the earlier 737-900, which had lower certified seating capacity.