In the United States Air Force, royal blue shoulder cords are worn by Noncommissioned Officers serving in the Special Duty Identifier of Military Training Leaders (MTLs). Similar to the Drill Instructors in the Army, MTLs are tasked with assisting Airmen undergoing technical training to transition from Basic Training to operational Air Force service.
The position of Military Training Leader was originally known as Student Training Advisor (STAs). In 1991, STAs were merged with Military Training Instructors to create the billet of Military Training Manager, but the new position was transformed into MTLs in 1998. With the change came a greater emphasis on leadership functions, and as a result MTLs are the constant “companions” of Airmen attending technical training schools that prep them for their first true assignments in their specific Air Force Specialty Code.