U.S. Air National Guard Master Sgt. Travis Metcalf, a crew chief with the 185th Air Refueling Wing, Iowa Air National Guard, oversees lowering of the boom on an Air Force KC-135 Stratotanker, November 3, 2015. The boom is being lowered while in the fuel cell hangar in Sioux City, Iowa in preparation for washing as part of a scheduled 180 day aircraft wash. (U.S. Air National Guard photo by: Master Sgt. Vincent De Groot 185ARW PA/released)