The Blériot-SPAD S.56 was a family of French airliners developed in the 1920s as various refinements of the S.33 design. All S.56 versions shared two new features: the first was a newly designed, all-metal wing, replacing the wooden wing of earlier related designs and the second was a redesigned passenger cabin, replacing the S.33's four single seats in a row with two rows of double seats. A second access door was also added.

The Bleriot-SPAD S.33 was a small French airliner developed soon after World War I. The aircraft was a biplane of conventional configuration whose design owed much to the Blériot company's contemporary fighter designs such as the S.20. Four passengers could be accommodated in an enclosed cabin within the monocoque fuselage, and a fifth passenger could ride in the open cockpit beside the pilot. A great success, the S.33 dominated its field throughout the 1920s, initially on CMA's Paris-London route, and later on continental routes serviced by Franco-Roumaine.