Today, Boeing celebrated their 5000th 737. Interesting facts about this amazing airplane:

With more than 4,100 airplanes in service, the 737 represents more than a quarter of the total worldwide fleet of large commercial jets flying today. More than 541 operators fly 737s into more than 1,200 cities in 190 countries. It is estimated that approximately 1,250 737s are in the air at any given moment, with one taking off or landing every 4.6 seconds.

This particular plane is going to Southwest Airlines, and is the 447th 737 to join their fleet. In fact, it is the only airplane that Southwest uses. Part of their low fare philosophy is to use a standard airplane that all pilots and mechanics are familliar with.