1st Lt. Jayce Gravdahl, 349th Air Refueling Squadron pilot, tests the KC-135 Stratotanker electrical system during a pre-flight check March 25, 2021, at McConnell Air Force Base, Kansas. During a pre-flight check, aircrew members test equipment to ensure everything functions properly before takeoff. (U.S. Air Force photo by Airman 1st Class Zachary Willis)