Knowles retires
Chief Master Sgt. Christopher H. Knowles, 934th Aeromedical Evacuation Squadron, retires from service at the Minneapolis-St. Paul Air Reserve Station, Minn. Friends, family and fellow Airmen came to help celebrate Chief Knowles 30 year career with the United States Air Force. (U.S. Air Force photo by Staff Sgt. Corban Lundborg/Released)