The Caudron C.690 was single-seat training aircraft developed in France in the late 1930s to train fighter pilots to handle high-performance aircraft. It was a conventional low-wing cantilever monoplane that bore a strong resemblance to designer Marcel Riffard's racer designs of the same period. Caudron attempted to attract overseas sales for the aircraft, but this resulted in orders for only two machines - one from Japan, and the other from the USSR. In the meantime, the first of two prototypes was destroyed in a crash that killed René Paulhan, Caudron's chief test pilot.