ELLSWORTH AIR FORCE BASE, S.D.--Capt. Dennis Bone, 34th Bomb Squadron B-1B Lancer weapons systems officer, proceeds through a weapons system preflight checklist Nov. 23. As a weapons systems officer, Captain Bone integrates with the pilot to collectively achieve and maintain crew efficiency, situational awareness and mission effectiveness. (U.S. Air Force photo/Airman 1st Class Corey Hook)