The Aviatik C.I was an observation aircraft which came into service during World War I in April 1915. It was the successor to the Aviatik B.I and B.II models. In the C.I the observer sat in front of the pilot, with two machine-guns, mounted on rails on each side of the observer's cockpit, which gave the crew the means to attack enemy aircraft.[clarification needed] The positions of the pilot and observer were reversed in the C.Ia version. Later models of the plane included the Aviatik C.II and the C.III, which had more powerful engines. The C.III was produced in large numbers.