ELLSWORTH AIR FORCE BASE, S.D.--Lt. Col. Jason Combs, 28th Bomb Wing director of staff, works his way through pre-flight checklists from the cockpit of a B-1B Lancer, Oct. 15. The pilot performs pre-flight checks to ensure all systems are functioning before every mission. (U.S. Air Force photo/Airman 1st Class Corey Hook)