Daily Quiz for May 10, 2014

Stratoliner 307. Test flights above 5,000 feet showed the need for pressurized cabins to allow pilots and passengers to fly above the clouds at 20,000 feet+. Boeing developed the Stratoliner 307 with pressurization, air conditioning and heat. The prototype first flew on Jan. 1, 1938. Although the plane was a major step forward only 10 were built.