Capt. Don Davenport and Capt. Mark Vaught run through their checklist prior to take off on board a KC-135 Stratotanker at Selfridge Air National Guard Base, Mich., July 21, 2011. The tankers are operated by the 127th Air Refueling Group, a component of the Michigan Air National Guard. (USAF photo by John S. Swanson)