U.S. Air Force Staff Sgt. Cody Harpster, assigned to the 126th Aircraft Maintenance Squadron, Illinois Air National Guard, observes the tail of a KC-135R Stratotanker as the aircrew members perform pre-flight checklist items at Scott Air Force Base, Ill, March 29, 2016.
(U.S. Air National Guard photo by Staff Sgt. Andrew Kleiser). Original public domain image from Flickr