U.S. Air Force Senior Airman Ben Alesse, an A-10 Thunderbolt II crew chief assigned to the 354th Aircraft Maintenance Squadron Davis-Monthan AFB, Ariz., goes over the comm checklist when the pilot's radio fails to transmit prior to takeoff during Angel Thunder in Tucson, Ariz., Oct. 17, 2011. Approximately 1,400 U.S. military, federal and state employees and coalition forces are participating in the 6th Annual Angel Thunder Exercise in Tucson, Ariz. Angel Thunder is the world's largest military search and rescue exercise in the world.