Tech. Sgt. Colleen Barringer, a United States Air Force military training instructor from the 331st Training Squadron, marches a flight of newly arrived trainees after receiving their first Air Force haircuts at Joint Base Sano Antonio-Lackland, Texas, April 8, 2015. Known as the "Gateway to the Air Force," all enlisted Airmen complete basic military training at Lackland, where more than 30,000 new Airmen graduate every year. (U.S. Air Force photo/Tech. Sgt. Trevor Tiernan)