Pilots, navigators/combat systems officers, aircrews, remotely piloted aircraft (RPA) crews, and missile crews continue to wear olive green or desert tan one-piece flight suits, or the two-piece OCP pattern flight suit. All three are made of Nomex for fire protection when performing or in direct support of flying or missile duties, or when otherwise prescribed. The one piece flight suits are required for any aircrew position in which ejection seats are used. Aircrew not in an ejection seat and ground based crews, like RPA and missile crews, may wear either the two or one piece flight suits.