Lt. Col. Eric Wilks and Lt. Col. Marvin Ashbaker, pilots with the 465th Air Refueling Squadron, conduct pre-flight checks aboard the Air Force Reserve Command’s first KC-135 to be upgraded with Block 45 May 5, 2016, at Tinker Air Force Base, Okla. Block 45 provides a digital display of engine controls, an updated autopilot, a new altimeter and software upgrades, ensuring that the KC-135 can perform well into the future as the workhorse of the air refueling fleet. (U.S. Air Force photo/Tech. Sgt. Lauren Gleason)