CHECKLIST U.S. Air Force Staff Sgt. Andrew Green performs a pre-flight checklist over the desert during exercise Angel Thunder on Davis-Monthan Air Force Base, Ariz., April 15, 2010. Green is assigned to the 55th Rescue Squadron. Angel Thunder 2010 is an Air Combat Command-sponsored exercise. It will be the largest personnel recovery and combat search and rescue exercise to date, combining Defense Department and non-department assets. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 281077-R-UAX68-721.jpg Photo Gallery