[fltsim.X] title=Boeing 737-400 PaintX sim=Boeing737-400 model= panel= sound= texture=X kb_checklists=Boeing737-400_check kb_reference=Boeing737-400_ref atc_id=N337UA atc_airline=United atc_flight_number=496 atc_id_color=0xffffffff ui_manufacturer=Boeing ui_type=737-400 ui_variation=United Airlines description=One should hardly be surprised that the world's most prolific manufacturer of commercial aircraft is also the producer of the world's most popular jetliner. The 737 became the best-selling commercial jetliner worldwide when orders for it hit 1,831 in June 1987 (surpassing Boeing's own 727 as the previous champ). However, it wasn't always that way\s in the first few years of production, there were so few orders that Boeing considered canceling the program. They didn't, and the airplane has more than proven itself in over three decades of service.