U.S. Air Force Staff Sgt. Edgar Corona, assigned to the 52nd Medical Operations Squadron, swims 15 meters while keeping his rifle above water during the water survival training portion of the U.S. Army Ranger training course inside the Ramstein Aquatic Center at Ramstein Air Base, Germany, March 2, 2012. The required three-day course prepares qualified Airmen for training at the U.S. Army Ranger training school at Fort Benning, Ga.