Joint Regulation 4120.15E: Designating and Naming Military Aerospace Vehicles is the current system for designating all aircraft, helicopters, rockets, missiles, spacecraft, and other aerial vehicles in military use by the United States Armed Forces.
United States Department of Defense Directive 4120.15 "Designating and Naming Military Aircraft, Rockets, and Guided Missiles" was originally issued November 24, 1971 and named the Air Force as the Executive Agent empowered to carry out the directive. Directive 4120.15 was implemented by Air Force Regulation (AFR) 82-1/Army Regulation (AR) 70-50/Naval Material Command Instruction (NAVMATINST) 8800.4A on March 27, 1974. The Joint Regulation designation system was heavily based upon the 1962 US Tri-Service aircraft designation system but also took control of the previously separate designation system for missiles and drones.
The current version was enacted by Joint Regulation 4120.15E Designating and Naming Military Aerospace Vehicles and was implemented via Air Force Instruction (AFI) 16-401, Army Regulation (AR) 70-50, Naval Air Systems Command Instruction (NAVAIRINST) 13100.16 November 3, 2020. The 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.
There are two basic components to a craft's identity: its vehicle designation and its popular name. A vehicle designation is sometimes referred to as a Mission Design Series (MDS), referring to the three main parts of the designation that combine to form a unique profile for each vehicle. The first letters (up to four) signify the type of craft and its mission. The design number, preceded by a dash "-", essentially signifies the product design of the aircraft (i.e. design 16 in F-16A). The series number identifies the specific "production model of a particular design number" with subsequent series indicating major revisions or changes. Finally, there may be variant and block identifiers which clarify the exact configuration of the vehicle.
The popular name is a matter of less specific construction, but is aimed at providing an official common name which eases identification and communication regarding the vehicle. The popular name is not used in official internal publications (an official internal report would refer to the "F-16" and "AIM-9" but not mention the names "Fighting Falcon" or "Sidewinder"). The popular name may be based on the manufacturer's internal name for the craft but all popular names must have the manufacturer's permission and be approved by the DoD. Pilots often have their own nicknames for their aircraft which may bear only coincidental resemblance (if that) to the official popular name, although some pilot nicknames are similar or even derived from the official popular name (such as "Bug" and "Super Bug" for the F/A-18 Hornet and F/A-18E/F Super Hornet).
There are seven potential components of a system's MDS designation as well as three potential components which are not included in the MDS.
| Component | Meaning | Example | |
|---|---|---|---|
| Status Prefix | (Optional) prefix to denote vehicles with unique status, such as non-flying or experimental | "X" in XWC-130J denotes experimental | |
| Modified Mission | (Optional) additional mission identifier which clarifies or notes modification of the basic mission (not used in missiles/rockets) | "W" in XWC-130J denotes weather-related modified mission | |
| Launch environment (missile/rocket only) | Identifies method of launch for missiles and rockets | "A" in AGM-158 denotes air-launched | |
| Mission | Identifies the basic design mission of the craft | "C" in XWC-130J denotes cargo mission | |
| Vehicle Type | (Optional) identifier used for non-standard vehicle types | "H" in UH-60 denotes helicopter | |
| Design Number | Number assigned to each design of the same mission type, with a dash separating the mission and design number | "130" in XWC-130J | |
| Series | Letter suffix to indicate which series within a design the vehicle belongs to | "J" in XWC-130J |
| Component | Meaning | Example | |
|---|---|---|---|
| Configuration/Component Number | Specifies configuration changes made to the aircraft which affect handling, maintenance, etc. | ||
| Block Number | Specifies a production group of aircraft built by the manufacturer | KC-135 Block 45 | |
| Serial Number | Identifies the specific aircraft being discussed | 68-10357 (see below) |
| E | Digitally developed. Vehicles that are developed in a digital environment. | |
| G | Grounded. Applied to aircraft which are permanently grounded, most often used for ground training of crews and support. This is only applied as a permanent designation. Use is rare. | |
| J | Temporary Special Test. Applied to craft involved with special testing of temporarily installed equipment. The J Prefix is used for aircraft that can be reasonably returned to their original configuration following tests. An example is aircraft used as testbeds for new electronics, but which will or may not retain that equipment after tests are complete. | |
| N | Permanent Special Test. Applied to craft involved with special testing on a permanent basis, with modifications to their configuration that make return to original configuration impractical. Many military aircraft transferred to NASA for aeronautical research carry this designation. | |
| X | Experimental. Applied to craft which are not yet accepted for service, or to prototypes for which standard configuration has not been finalized. Most prototypes of the past carried this prefix, but it should not be confused with craft given an X basic mission symbol. The X status prefix is for designs for other missions, but at an experimental stage of the design process. An example shown earlier is the XWC-130J. | |
| Y | Prototype. Originally applied to demonstration craft where configuration had been determined, but from the 1970s on applied to all prototypes of aircraft intended for production. An example would be the prototype YF-22 | |
| Z | Planning. Applied to designs in the planning/pre-development phase. |
Many craft have been designed for more specific missions than their basic mission symbol would indicate, and many design series have been designed for different missions than the original design, and may or may not still maintain capability for the original mission. The modified mission symbol provides the services the ability to accurately indicate a craft's mission without losing commonality with the basic design MDS. If utilized, the modified mission symbol is placed as a prefix directly in front of the basic mission symbol (but after any applicable status prefix, see above). Modified mission symbols are not used for rockets and missiles. Currently authorized modified mission symbols are:
| A | Attack. Similar to the basic mission symbol, A applies to aircraft modified to attack land or sea targets. Example is the AC-130U Spectre, a transport modified for ground attack missions. | |
| C | Cargo. Similar to the basic mission symbol, C applies to aircraft modified to carry cargo and passengers. An example is the CT-39A, a T-39A modified for carrying cargo. | |
| D | Director. Applies to aircraft modified to control unmanned aerial vehicles such as drones. An example is the DT-2B a T-2B modified to control drones. | |
| E | Electronics. Applies to aircraft modified with addition of extensive electronic equipment, either for enhancement of their basic mission, or as a platform for specifically electronic missions such as providing electronic countermeasures (ECM), airborne early warning (AEW), airborne command and control (ACC), or communications relay. Example is the EP-3A Orion, a patrol aircraft outfitted with special electronics to collect electronic data. | |
| F | Fighter. Similar to the basic mission symbol, F applies to aircraft modified to engage in air combat. The FA-18 and FA-22 are special examples of this. | |
| H | Search and Rescue. Similar to the basic mission symbol, H applies to aircraft modified to assist search and rescue (SAR) operations. Example is the HU-25 Guardian, a utility transport modified for Coast Guard search and rescue coordination. | |
| K | Tanker. Applies to aircraft modified to carry and transfer aviation fuel in flight to other aircraft. Example is the KA-6D Intruder, an attack aircraft modified with tanks and hoses to provide aerial refueling. | |
| L | Cold Weather. Applies to aircraft modified to operate in Arctic or Antarctic environments. Example is the LC-130, a transport modified to deliver logistics support to Antarctic stations. | |
| M | Multi-Mission. Applies to aircraft modified to perform various missions, in particular special operations modifications. Also used as a catch all for missions that neither fit in any category, nor warrant their own. An example would be the MC-130H, a cargo aircraft modified to support special operations needs. | |
| O | Observation. Applies to aircraft modified to perform observation of enemy or potential enemy positions, forward air control (FAC), and patrol borders or areas of potential infiltration. Example is the OA-10A, an attack aircraft modified to provide observation of enemy territory. | |
| P | Patrol. Similar to the basic mission symbol, P applies to aircraft modified to perform maritime patrol. Example is the P-3 Orion. | |
| Q | Drone. Applies to craft modified to operate unmanned, under control of ground or air directors or autonomously. Example is the QF-106 Delta Dart, a fighter modified to fly under remote control as a target for missile testing. | |
| R | Reconnaissance. Similar to the basic mission symbol, R applies to aircraft modified to perform air reconnaissance of enemy forces, territory, and facilities. Example is the RF-5E Tiger II, a fighter with added reconnaissance cameras and equipment for photographing enemy positions. | |
| S | Anti-Submarine. Similar to the basic mission symbol, S applies to aircraft modified to search for, locate, and attack enemy submarines like the SZ-1A | |
| T | Training. Similar to the basic mission symbol, T applies to aircraft modified for use as trainers, both initial and operational. Examples are two-seat operational training versions of single-seat aircraft, such as the TA-4J and TF-102. Fully combat-capable two-seaters are usually simply assigned a new series letter. | |
| U | Utility. Similar to the basic mission symbol, U applies to aircraft modified to allow use as utility and base support aircraft. An example is the UC-12B, modified for utility by adding a cargo door. | |
| V | Staff/VIP. Applied to aircraft modified for transport of staff and ranking personnel with furnishment of comfortable accommodations. Example is the VC-25, a 747 modified to serve as the Presidential transport, or Air Force One. | |
| W | Weather. Applied to aircraft modified for weather monitoring and air sampling to detect nuclear, biological, and chemical contamination and for intelligence gathering on foreign nuclear testing. An example is the WC-135. |
The basic mission symbol is the heart of the mission part of the designation. No designation is without it, and some designations consist of only a basic mission symbol for the mission part, such as the F-14 or C-130. The following are the officially authorized basic mission symbols:
For non-standard vehicle types (vehicles other than piloted, fixed-wing and self-propelled aircraft which are wholly supported by aerodynamic lift from liftoff to touchdown), a final symbol is added after the basic mission symbol to identify the vehicle type. Current applicable symbols are as follow:
The design number is separated from the earlier components by a dash. Design numbers run consecutively from 1 to 999.
The series letter follows the design number and progresses consecutively starting with A. In the event the series letter "Z" is used, the design number will progress to the next unused number and series will begin again at "A". To avoid confusion, series "I" and "O" are not used.
Configuration/component numbers signify changes that "affect performance, tactics, or integral components of a weapon system." They appear to the right of the series symbol and are separated from the series symbol by a dash.
The block number specifies a group of aircraft produced to the same specifications by the manufacturer. Block numbers are assigned in multiples of 5 (01, 05, 10). An example is F-16C Block 25.
Serial numbers are located on the tail and identify a specific aircraft. For example, MH-53M Pave Low IV serial number 68-10357 was the Pave Low which carried the mission commanders during the Sơn Tây raid. For more information on serial numbering of military aircraft, see United States military aircraft serial numbers.
Status prefix is an optional prefix not always used for vehicles in regular service. If used, it is the first letter in the MDS. Authorized current status prefixes are:
All rockets and missiles contain a symbol to indicate the launch method, be it from the air, ground, sea, etc. The following are the currently authorized symbols for launch environments. These are not used for other aerospace vehicles.
Rockets and missiles are assigned a single mission symbol, which usually denotes the intended target type of the missile. For most types of missile, the combination of launch environment and mission symbols form a from-to combination (surface-to-air, ship-to-submarine) that gives one a good idea of the potential uses for the missile.
For rockets and missiles, the vehicle type symbol identifies the basic vehicle type and will be the final symbol in the mission part of the MDS.
The design number is separated from the earlier components by a dash. Design numbers run consecutively from 1 to 999.
The series letter follows the design number and progresses consecutively starting with A. In the event the series letter "Z" is used, the design number will progress to the next unused number and series will begin again at "A". To avoid confusion, series "I" and "O" are not used.