Aircraft maintenance crews stand by their aircraft, preparing several KC-135 Stratotankers for take-off at Selfridge Air National Guard Base, Mich., Oct. 22, 2011. The Airmen and aircraft, all attached to the 127th Air Refueling Group of the Michigan Air National Guard, were participating in a training exercise during their October Unit Training Assembly. Airmen in the Michigan Air National Guard perform one “drill weekend” per month to stay current in various skill specialties. The Guardsmen are also on-call to respond to the need for Airmen and aircraft in both domestic and international operations. (U.S. Air Force photo by MSgt. Terry Atwell)