EC-121 Super USAF and USN four-engine, prop-driven, Constellation long-range, heavy transport modified with special equipment for radar early warning patrols and electronic warfare duty. Built by Lockheed. FADAC Field Artillery Digital Automatic Computer FDC Fire Direction Center F-8 Crusader U. S. Navy and Marine Corps supersonic, single-seat, single-engine, jet fighter with afterburner. Primarily used in South Vietnam in an attack role. Carries air-to-air and air-to-ground ordnance. Built by LTV Vought Aeronautics. F-4B Phantom II U. S. Navy and Marine Corps twin-engine, two-seat, supersonic fighter/attack jet with afterburners; has dual role of interceptor and bomber. Of all U. S. naval attack aircraft, F-4B carries second largest payload. Built by McDonnell. F-4C U. S. Air Force model of the Phantom II. 1st ACD 1st Air Cavalry Division 1st MarDiv 1st Marine Division 1st MAW 1st Marine Aircraft Wing FOB-3 Forward Operating Base 3 F-100 Super Sabre Single-engine, jet (with afterburner) sweptwing, supersonic fighter-bomber; in production since 1953, the F-100 was the first supersonic operational fighter developed for the U. S. Air Force. Carries air-to-air and air-to-ground ordnance. Built by North American. F-105 Thunderchief U. S. Air Force supersonic, single-seat, single-engine, jet fighter/bomber with afterburner. Built by Republic. FMFPac Fleet Marine Force, Pacific FO Forward Observer FSCC Fire Support Coordination Center GCA Ground Controlled Approach GPES Ground Proximity Extraction System Grenade Launcher, U. S.-built, single-shot, break-open, M-79 breech-loaded shoulder weapon which fires 40mm projectiles and weighs approximately 6.5 pounds when loaded; it has a sustained rate of aimed fire of 5-7 rounds per minute and an effective range of 375 meters.