Hoover flew Spitfires in the United States Army Air Forces during World War II and was shot down in 1944 off the coast of France. He was held for over a year in a German POW camp before eventually escaping and flying to safety in a stolen enemy aircraft. He then worked as a United States Air Force and civilian test pilot after the war, flying chase for the Bell X-1 supersonic flight, and as a flight instructor for North American Aviation during the Korean War.