Captain Duer was the pilot of a F-80C Shooting Star fighter-interceptor with the 35th Fighter Bomber Squadron, 8th Fighter Bomber Group. On April 30, 1952, he was on a bombing mission against a railway complex in North Korea when his aircraft developed a fire in the cockpit and his aircraft crashed in the sea. He ejected and was taken Prisoner of War. He was presumed dead on December 31, 1953. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.