Boeing [NYSE: BA] today begins final assembly of the first 737-900ER (Extended Range), the newest member of the world's most successful single-aisle airplane family. The wings and landing gear shown here are being joined to the 737-900ER fuselage in the Boeing manufacturing facility in Renton, Wash. Last-stage assembly and interiors installation will begin once the airplane joins the moving assembly line. The 737 derivative incorporates an extra pair of exit doors, a flat aft-pressure bulkhead and other structural and aerodynamic changes that allow it to carry more passengers and fly farther than the 737-900. The twin-engine jet can carry up to 215 passengers and fly up to 3,200 nautical miles (5,900 km). The 737-900ER, destined for Indonesian-based launch customer Lion Air, will embark on a five-month flight test program later this year.