SGT Drew, 31st Air Defense Artillery (ADA) Brigade, HHB S1, Fort Bliss, Texas prepares map grid coordinates for troop movements in preparation for night maneuvers. The 31st ADA's Patriot missile provided the air defense during the world's largest joint service, multi-national tactical air operations exercise. (Duplicate image, see also DD-SD-01-04271 or search 970418-F-6655M-107)