Sikorsky S-40
The Sikorsky S-40 was a four-engine amphibious flying boat built by Sikorsky for Pan American Airways and first flown in 1931. Only three were built, all for Pan Am; the first, christened American Clipper, began the airline's Clipper naming tradition and served as its flagship. The three aircraft carried 38 passengers on Pan Am's Caribbean and Latin American services, flew more than 10 million miles without incident in civilian service, and finished their careers as US Navy trainers in the Second World War. None survives.