U.S. Air Force Lt. Col. Mark Hole, pilot, and Captain Thomas Bryceland, co-pilot, 185th Air Refueling Squadron, prepare for takeoff in the KC-135 Stratotanker for the last time during the last training mission of the 137th Air Refueling Wing on Tinker Air Force base, June 30, 2015 at Tinker Air Force base, Okla. The 137th ARW will be transitioning to Air Force Special Operations Command. (U.S. Air Force photo by Tech Sgt. Caroline Essex/Released)