High Quality Content by WIKIPEDIA articles! The 1962 United States Tri-Service aircraft designation system is a unified designation system introduced by the United States Department of Defense on 18 September 1962 for all the U.S. military aircraft. Prior to this date, each armed service used their own nomenclature system. Under the 1962 system, almost all aircraft receive an unified designation, whether operated by the United States Air Force (USAF), United States Navy (USN), United States Coast Guard (USCG), United States Marine Corps (USMC), or the United States Army. Experimental aircraft operated by manufacturers or the National Aeronautics and Space Administration are also often assigned numbers in the X-series.