2LT Sison and SPC Hooper, 31st Air Defense Artillery (ADA) Brigade, HHB S2, Fort Bliss, Texas prepare map grid coordinates for the movement of troops in preparation for night maneuvers. The 31st ADA Patriot missile batteries move to various locations during this, the world's largest joint service, multi-national tactical air operations exercise. (Duplicate image, see also DD-SD-01-04272 or search 970418-F-6655M-108)