11/10/2012 - Senior Airman Michael Murray, an aircraft maintainer assigned to the 90th Expeditionary Air Refueling Squadron, Incirlik Air Base, Turkey, conducts a Mode 4 test on a KC-135 Stratotanker prior to takeoff, Nov. 10, 2012. Mode 4 is an aircraft identification system used by military aircraft to identify other aircraft as friend or foe. Murray is an AIr Force Reservist assigned to the 931st Air Refueling Group, McConnell Air Force Base, Kan. (U.S. AIr Force photo by 1st Lt. Zach Anderson)