Sikorsky S-40 Over Pan Am's Florida base Art Print by Aviation Artist Roger H. Middlebrook GAvA

Built in response to a request from Pan Am's illustrious director, Juan Trippe, the S-40 pushed the boundaries of what was possible in commercial aviation and laid the foundations for later aircraft such as the same company's S-42 and Boeing's Model 314 Clipper.

While pushing many boundaries, the aircraft was by no means perfect and the large assortment of struts and wires led to the nickname of "The Flying Forest" being given.  Very much a work in progress and what would be classed now as a "Proof of Concept", only three S-40 were built, named Caribbean Clipper, American Clipper and Southern Clipper, entering passenger carrying service in 1931. Later, in 1935, the aircraft were upgraded with new engines and having been superceded in the fleet by the S-42 continued to give service to Pan Am and after America joined WWII in the US Navy, with whom they were finally scrapped in 1943.