U.S. Air Force Senior Master Sgt. Jason Colvin, an engineering shop superintendent assigned to the 307th Civil Engineer Squadron, retires at Barksdale Air Force Base, Louisiana, Oct. 20, 2019, after 24 years of service. Colvin led construction projects for both humanitarian and base support functions, and served as a mentor to his Airmen during his time in service. (U.S. Air Force photo by Tech. Sgt Callie Ware)