first issued in 1971 and most recently updated in 2020 (4120.15E incorporating Change 02 "Designating and Naming Military Aerospace Vehicles") is implemented via Air Force Instruction 16-401/Army Regulation 70-50/Naval Air Systems Command Instruction (NAVAIRINST) 13100.16 (3 November 2020) and describes both systems. A list of US military aircraft was kept via 4120.15-L Model Designation of Military Aerospace Vehicles 31 August 2018 until its transition to data.af.mil on 31 August 2018. See also List of military aircraft of the United States List of undesignated military aircraft of the United States List of U.S. DoD aircraft designations Military aircraft United States military aircraft engine designations References Citations Bibliography External links A comprehensive explanation can be found at Systems of Designation. American military aviation United States military-related lists United States