JOINT BASE SAN ANTONIO-RANDOLPH, Texas -- Air Force Chief of Staff Gen. Mark A. Welsh III (left) passes the Air Education and Training Command guidon to Lt. Gen. Darryl Roberson, commander of AETC, during a change of command ceremony at Joint Base San Antonio-Randolph, Texas, July 21, 2015. The change of command ceremony represents the formal passing of responsibility, authority and accountability of command from one officer to another. (U.S. Air Force photo by Johnny Saldivar)