The Fokker F.IX was an airliner developed in the Netherlands in the late 1920s, intended to provide KLM with an aircraft suitable for regular services to the Dutch East Indies.

When the onset of the Great Depression forced the postponement of those plans, the market for this aircraft disappeared as well, although it did see military service in Czechoslovakia as a bomber.

[2][3] The first example, registration PH-AGA, powered by three Gnome-Rhône Jupiter radial engines rated at 480–500 hp (360–370 kW), made its maiden flight on 26 August 1929.

Due to the logistics implications of stocking spare parts for only two aircraft, these were confined to European routes and the two F.IXs each made only one flight to the Indies.

One (registration PH-AFK) was written off in a crash on 4 August 1931, and the other (De Adelaar, PH-AGA) was retired in 1936, and was subsequently acquired by clandestine means to serve as a bomber in the Spanish Republican Air Force during the civil war.