Maj. Nathan Graber, 158th Fighter Wing, prepares his F-16 Fighting Falcon to fly as part of an ‘alert’ exercise at Langley Air Force Base, Va. Aug. 1, 2011. The 158th FW, an Air National Guard unit from Vermont, remains on alert 24 hours a day in case they need to immediately launch aircraft in support of homeland security. (U.S. Air Force photo by Staff Sgt. Logan Tuttle/Released)