A U.S. Air Force F-16D Fighting Falcon from the New Jersey Air National Guard's 177th Fighter Wing is refueled by Tech. Sgt. Santiago Avila, boom operator on a KC-135 Stratotanker from the Utah Air National Guard, en route to Operation Snowbird (OSB) training at Davis-Monthan Air Force Base, Ariz., on Feb. 19, 2014. Southern Arizona provides optimal weather conditions and ample ranges that mirror the environment found downrange, and OSB hosts an average of 10-12 units per year with two to 12 aircraft per visit for an average of two weeks. (U.S. Air National Guard photo by Master Sgt. Andrew Moseley/Released)