Aircraft rescue and firefighting Marines with Headquarters and Headquarters Squadron at Marine Corps Air Station Yuma, Ariz., suit up prior to a demonstration for aviation ground support (AGS) students of the Weapons and Tactics Instructor course 1-15 on MCAS Yuma’s flight line, Tuesday, Sept. 9, 2014. The demonstration acquainted the AGS students, who come from a variety of technical backgrounds and military occupational specialties, with the flight line’s terminology, markings and resident services.