Microsoft Flight Simulator 2004: A Century of Flight

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; 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.

The reason for the 737's great success is its design flexibility. It lends itself well to modifications that fit the market needs of its customers, and currently, seven different variants are available. The ability to order different versions of the same plane allows an airline to fit the airplane to a particular route and passenger load while maintaining a smaller inventory of support and service equipment for its fleet. And, like all of the planes in this family, the 737-400 has crew commonality with its siblings-a pilot qualified to fly one is qualified to fly all of them.