Boeing employees in Renton, WA prepare to fasten wings of the first Boeing 737-900 to the 124-foot-long (37.8 meter) body section. The 737-900 is the longest of the Next-Generation 737s, and can seat up to 189 passengers in a one-class configuration. Next-Generation 737s are the newest, most advanced-design airplanes in their class, and feature an improved wing design that allows the airplanes to fly higher than competing Airbus A321 airplanes. A higher maximum cruising altitude means passengers can enjoy a smoother ride and airlines benefit by being able to fly above bad weather, congested routes and less capable airplanes.