On February 5, 1999, The 737-900 reached firm design configuration, a key milestone in the development of the longest Next-Generation 737 model. Measuring 138 feet, 2 inches in length, the 737-900 model surpasses the 737-800 by nearly nine feet. The increased size accommodates about 18 percent more cargo volume and about 9 percent more passenger cabin area than the 737-800.