U.S. Air Force Staff Sgt. Jason Cokley, 909th Aircraft Maintenance Unit crew chief, plugs in a power source to a KC-135 Stratotanker assigned to the 909th Air Refueling Squadron April 20, 2017, at Kadena Air Base, Japan. Crew chiefs play a vital role in ensuring aircraft are ready for flight and pre-flight inspections by pilots. (U.S. Air Force photo by Senior Airman Lynette M. Rolen)