Boeing’s 737 factory at the Renton, Wash., site leads the industry as the most efficient airplane factory in the world. More than 11,600 commercial airplanes (707, 727, 737, and 757) or about 30 percent of the worldwide fleet flying today were built in Renton. According the Guinness World Records, the 737 is the “most produced large commercial jet” in aviation history. Covering 1.1 million square feet of factory space, the 737 program rolls out 42 airplanes a month and is expected to increase the rate to 47 a month in 2017 and 52 in 2018. From the time a fuselage enters the factory, it takes 10 days to complete an airplane. The final assembly building has two moving lines producing Next-Generation 737s and a third that will initially produce the 737 MAX beginning in 2015. The P-8, a Navy submarine hunter and maritime patrol aircraft, and a military derivative of the 737-800, is also built at Renton.