The S-43 first flew in 1935, and was a smaller version of the Sikorsky S-42 "Clipper". It accommodated between 18 and 25 passengers, with a separate two-crew forward cockpit. The S-43 was known as the "Baby Clipper" in airline service.
On April 14, 1936, An S-43 with a 500 kilograms (1,100 lb) payload and piloted by Boris Sergievsky set an altitude record for amphibious aircraft when it reached an altitude of 27,950 feet above Stamford, Connecticut. Also aboard was designer Igor Sikorsky.
In total, approximately 53 S-43s were built, including examples of the twin-tailed S-43B.
Five aircraft were acquired by the U.S. Army Air Corps in 1937 under the designation OA-8 and were used for transport of freight and passengers. 17 aircraft were procured by the U.S. Navy between 1937 and 1939 as the JRS-1, two of which served the U.S. Marine Corps. One JRS survived in service at the end of 1941.
Two aircraft went to private owners: Harold Vanderbilt and Howard Hughes. Hughes' S-43 N444 remains the last example of this aircraft type flying . It is now owned by Kermit Weeks and has been relocated from Texas to the restoration facility at the Fantasy of Flight Museum in Polk City, Florida where it is awaiting reassembly and restoration.
June 2, 1937: A Linea Aerea Nacional de Chile S-43 disappeared over the Sea of Chile with 9 on board.
August 2, 1937: A Pan Am Grace Airways (Panagra) S-43NC 15065 crashed in the vicinity of Coco Solo, Canal Zone; all 14 on board died. The plane spiraled into the water at approximately 90 mph and was destroyed by an immediate explosion and fire. Most probable cause of the crash was failure of one or both of the engines due to a faulty gasoline system and/or sudden and severe rain, as the pilot indicated losing altitude two times in the three minutes prior to the crash.
August 8, 1937: A China National Aviation Corporation (CNAC) S-43 ditched at Chilang Point, Bias Bay, China, killing the three crew; all 8 passengers survived. The flying boat was forced to ditch due to bad weather. High waves broke one wing off; the 8 passengers clung to the other wing until rescued.
May 17, 1943: Hughes crashed his S-43 into Lake Mead, killing CAA inspector Ceco Cline and Hughes employee Richard Felt. The aircraft was later raised and restored to flying condition.