Senior Airman Greg Davidson climbs the netting on the first training obstacle named "Tough One." Senior Airman Greg Davidson, U.S. Air Force, climbs the netting on the first training obstacle named "Tough One," at Fort Huachuca, Ariz., on Oct. 14, 2004. Members of U.S. Air Forces in Europe Defender Challenge team are spending three weeks in Sierra Vista, Ariz., preparing for the 2004 Defender Challenge competition being held at Lackland Air Force Base, Texas. Defender Challenge is a security forces competition pitting teams from major commands against one another over a series of events including marksmanship, tactics and physical fitness. Davidson is assigned to the 48th Security Forces Squadron, Lakenheath Air Base, United Kingdom. SHARE: Download: Full Size (0.04 MB) Credit: VIRIN: 785025-J-WLX91-261.jpg Photo Gallery