The Tri-Service aircraft designation system is a unified system introduced in 1962 by the United States Department of Defense for designating all U.S. military aircraft. Prior to then, the U.S. armed services used separate nomenclature systems.
Under the tri-service designation system, officially introduced on 18 September 1962, almost all aircraft receive a unified designation, whether they are operated by the United States Air Force (USAF), United States Navy (USN), United States Marine Corps (USMC), United States Army, or United States Coast Guard (USCG). Experimental aircraft operated by manufacturers or by NASA are also often assigned designations from the X-series of the tri-service system.
The 1962 system was based on the one used by the USAF between 1948 and 1962, which was in turn based on the Type, Model, Series USAAS/USAAC/USAAF system used from 1924 to 1948. The 1962 system has been modified and updated since introduction.
The designation system produces a Mission-Design-Series (MDS) designation of the form:
- (Status Prefix)(Modified Mission)(Basic Mission)(Vehicle Type)-(Design Number)(Series Letter)
Of these components, only the Basic Mission, Design Number and Series Letter are mandatory. In the case of special vehicles a Vehicle Type symbol must also be included. The U.S. Air Force characterizes this designation system as "MDS", while the Navy, and Marine Corps refer to it as Type/Model/Series (T/M/S).
These optional prefixes are attached to aircraft not conducting normal operations, such as research, testing and development. The prefixes are:
- G: Permanently grounded
- J: Special test, temporary
- N: Special test, permanent
- X: Experimental
- Y: Prototype
- Z: Planning
A temporary special test means the aircraft is intended to return to normal service after the tests are completed, while permanent special test aircraft are not. The Planning code is no longer used but was meant to designate aircraft "on the drawing board". For example, using this system an airframe such as the F-13 could have initially been designated as ZF-13 during the design phase, possibly XF-13 if experimental testing was required before building a prototype, the YF-13; the final production model would simply be designated F-13 (with the first production variant being the F-13A). Continuing the example, some F-13s during their service life may have been used for testing modifications or researching new designs and designated JF-13 or NF-13; finally after many years of service, the airframe would be permanently grounded due to safety or economic reasons as GF-13.
Aircraft which are modified after manufacture or even built for a different mission to the standard airframe of a particular design are assigned a modified mission code. They are:
- A: Attack (i.e., air-to-surface)
- C: Transport (i.e., cargo)
- D: Drone director
- E: Special electronic mission
- F: Fighter
- H: Search and rescue, MEDEVAC
- K: Tanker
- L: Equipped for cold weather operations
- M: Missile carrier (1962–c.1972), Mine countermeasures (c.1973–1976), Multi-mission (1977 onwards)
- O: Observation
- P: Maritime patrol
- Q: Unmanned drone
- R: Reconnaissance
- S: Anti-submarine warfare
- T: Trainer
- U: Utility
- V: Staff transport
- W: Weather reconnaissance
The multi-mission and utility missions could be considered the same thing, however they are applied to multipurpose aircraft conducting certain categories of mission. M-aircraft conduct combat or special operations while U-aircraft conduct combat support missions, such as transport (e.g., UH-60) and electronic warfare (e.g., MC-12). The vast majority of U.S. Coast Guard air assets include the H-code (e.g., HH-60 Jayhawk or HC-130 Hercules).
All aircraft are to be assigned a basic mission code. In some cases, the basic mission code is replaced by one of the modified mission codes when it is more suitable (e.g., M in MH-53J Pave Low III). The defined codes are:
The rise of the multirole fighter in the decades since the system was introduced has created some confusion about the difference between attack and fighter aircraft. According to the current designation system, an attack aircraft (A) is designed primarily for air-to-surface missions (also known as "attack missions"), while a fighter category F incorporates not only aircraft designed primarily for air-to-air warfare, but also multipurpose aircraft designed also for attack missions. The Air Force has even assigned the F designation to attack-only aircraft, such as the F-111 Aardvark and F-117 Nighthawk.
The only A designated aircraft currently in the U.S. Air Force is the A-10 Thunderbolt II. The last front line A designated in the U.S. Navy and Marine Corps was the A-6 Intruder, with the only strictly A designated fixed-wing aircraft remaining is the A-29 Super Tucano leased under the Imminent Fury program.
Of these code series, no normal aircraft have been assigned a K or R basic mission code in a manner conforming to the system.
The vehicle type element is used to designate the type of aerospace craft. Aircraft not in one of the following categories (most fixed-wing aircraft) are not required to carry a type designator. The type categories are:
A UAV control segment is not an aircraft, it is the ground control equipment used to command a UAV. Only in recent years has an aircraft been designated as a spaceplane, the proposed MS-1A.
According to the designation system, aircraft of a particular vehicle type or basic mission (for manned, fixed-wing, powered aircraft) were to be numbered consecutively. Numbers were not to be assigned to avoid confusion with other letter sequences or to conform with manufacturers' model numbers. Recently this rule has been ignored, and aircraft have received a design number equal to the model number (e.g., KC-767A) or have kept the design number when they are transferred from one series to another (e.g., the X-35 became the F-35).
Different versions of the same basic aircraft type are to be delineated using a single letter suffix beginning with "A" and increasing sequentially (skipping "I" and "O" to avoid confusion with the numbers "1" and "0"). It is not clear how much modification is required to merit a new series letter, e.g., the F-16C production run has varied extensively over time. The modification of an aircraft to carry out a new mission does not necessarily require a new suffix (e.g., F-111Cs modified for reconnaissance are designated RF-111C), but often a new letter is assigned (e.g., the UH-60As modified for Search and Rescue missions are designated HH-60G).
Non-systematic aircraft designations
Since the 1962 system was introduced there have been several instances of non-systematic aircraft designations and skipping of design numbers.
Non-systematic or aberrant designations
The most common changes are to use a number from another series, or some other choice, rather than the next available number (117, 767, 71). Another is to change the order of the letters or use new acronym based letters (e.g. SR) rather than existing ones. Non-systematic designations are both official and correct, since the DOD has final authority to approve such designations.
- Designation conflicted with unrelated C-7 Caribou, redesignated EO-5C in August 2004.
- Originally, the Navy planned to have two variants of the Hornet: the F-18 fighter and A-18 light attack aircraft. During development, "F/A-18" was used as a shorthand to refer to both variants. When the Navy decided to develop a single aircraft able to perform both missions, the "F/A" appellation stuck. AF-18 or FA-18 would be conformant.
- The F designation is expected, but the series number 35 based on its X-35 designation, rather than the next available F- series number (24).
- BF-111, or using a much lower number in the bomber series would have been more systematic but 111 was retained for commonality with the F-111 from the pre-1962 system.
- Designated as part of series continuing from the pre-1962 system and latterly used to identify foreign aircraft acquired by the government, e.g., YF-113 was a MiG-23.
- The SR-71 designator is a continuation of the pre-1962 bomber series, which ended with the XB-70 Valkyrie. During the later period of its testing, the B-70 was proposed for the reconnaissance/strike role, with an RS-70 designation. The USAF decided instead to pursue an RS-71 version of the Lockheed A-12. Then-USAF Chief of Staff Curtis LeMay preferred the SR (Strategic Reconnaissance) designation and wanted the reconnaissance aircraft to be named SR-71. Before the Blackbird was to be announced by President Johnson on 29 February 1964, LeMay lobbied to modify Johnson's speech to read SR-71 instead of RS-71. The media transcript given to the press at the time still had the earlier RS-71 designation in places, creating the myth that the president had misread the aircraft's designation.
- Uses its own modified mission letter (T for Tactical) with basic mission letter (R for Reconnaissance). Later redesignated U-2R after the end of the Cold War in 1991.
- Skipped hundreds of C- series numbers to use Boeing's model number. Has conformant basic mission and modified mission letters. Only used for aircraft sold to foreign air forces. The U.S. Air Force ordered the Boeing 767-based tanker KC-46, which is the expected designation following the assignment of "KC-45" to the competing Airbus A330-derived bid, which itself skipped 42-44.
Skipped design numbers
The design number "13" has been skipped in many mission and vehicle series for its association with superstition. Some numbers were skipped when a number was requested and/or assigned to a project but the aircraft was never built.
The following table lists design numbers in the 1962 system have been skipped.
|Mission or Vehicle Series||Missing numbers||Next available number|
|A||8, 11, 15-28||30|
|C||16, 30, 34, 36, 39, 42–44||47|
|H||42, 49, 69, 73–91||93|
|K||n/a (K series was canceled)|
|T||4, 5, 50||54|
|U||12, 14, 15||29|
|V||14, 17, 19, 21||25|
|X||23, 39, 52*||58|
*: The X-23 and X-39 designations exist, but were never officially assigned. X-52 was skipped to avoid confusion with the B-52 Stratofortress.
From 1939, a 2-letter manufacturer's code was added to designations to easily identify the manufacturer and the production plant. For example, F-15E-50-MC, the "MC" being the code for the McDonnell Douglas plant at St. Louis, Missouri.
In 1941 block numbers were added to designations to show minor equipment variations between production blocks. The block number appears in the designation between the model suffix and manufacturers code (for example F-100D-85-NH). Initially they incremented in numerical order -1, -2, -3 but this was changed to -1, -5, -10, -15 in increments of five. The gaps in the block numbers could be used for post-delivery modifications, for example a F-100D-85-NH could be modified in the field to F-100D-86-NH. Not all types have used block numbers.
- ^ abc"DoD 4120.15-L, 'Model Designation of Military Aerospace Vehicles'"(Portable Document Format). US Department of Defense. 12 May 2004. Retrieved 2007-01-15.
- ^Designating and Naming Defense Military Aerospace Vehicles, U.S. DoD, 14 March 2005.
- ^DESIGNATING AND NAMING DEFENSE MILITARY AEROSPACE VEHICLES(PDF). United States Department of the Air Force. 14 April 2005. Retrieved 29 January 2011.
- ^16-401(I), pp. 17, "F - Fighter Aircraft designed to intercept and destroy other aircraft or missiles. Includes multipurpose aircraft also designed for ground support missions such as interdiction and close air support."
- ^Zarzecki, Thomas W. (2002). Arms diffusion: the spread of military innovations in the international system. New York [u.a.]: Routledge. p. 186. ISBN 0-415-93514-8.
- ^De Havilland RC-7B, designation-systems.net.
- ^Patricia Trenner, "A Short (Very Short) History of the F-19". Air & Space Magazine, 1 January 2008.
- ^MiG-23. FAS
- ^Non-Standard DOD Aircraft Designations. designation-systems.net
- ^Jenkins, Dennis R. Lockheed U-2 Dragon Lady, pp. 60–61. North Branch, MN: Specialty Press, 1998. ISBN 1-58007-009-4.
- ^"USAF selects Boeing for KC-X contract". Flight International
- ^Parsch, Andreas. "Missing" USAF/DOD Aircraft Designations. designation-systems.net
- ^Andrade 1979, p. 8
- ^ abcdAndrade 1979, p. 9
- Andrade, John (1979). U.S. Military Aircraft Designations and Serials since 1909. Midland Counties Publications. ISBN 0-904597-22-9.
A United States Department of Defense aerospace vehicle designation is determined by a detailed protocol which identifies all aircraft, helicopters, rockets, missiles, spacecraft, and other aerial vehicles in military use by the United States Armed Forces.
Individual system pages
The current United States Department of Defense system for naming and designating aircraft aims to provide a unified system across all services that applies to all military aerial and space craft. There are two basic components to a craft's identity: its designation, and its common 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 series of letters (up to four) determine the type of craft and designed mission. A series number identifies major types which are of the same type and mission, and finally a series of variant and block identifiers clarify the exact configuration of the vehicle.
The 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 common name is not used in internal publications (an official internal report would refer to the "F-16" and "AIM-9" but not mention the names "Fighting Falcon" or "Sidewinder"). Pilots often have their own nicknames for their aircraft which may bear only coincidental resemblance (if that) to the official common name, although some pilot nicknames are similar or even derived from the official common name (such as "Bug" and "Super Bug" for the F/A-18 Hornet and F/A-18E/F Super Hornet).
The current regulations and procedures relating to employing this system are laid out in DoD and branch documents, including Air Force Joint Instruction 16-401 , and are not classified. These regulations replaced the previous regulations which were originally introduced in 1962 (See 1962 United States Tri-Service aircraft designation system).
There are 10 potential components of a system's designation, comprising the three basic parts of the designation.
- Status Prefix
- Optional prefix to denote vehicles with unique status, such as non-flying or experimental.
- Modified Mission
- Optional additional mission identifier which clarifies or notes modification of the basic mission.
- Launch Environment
- Identifies method of launch for missiles and rockets.
- The most basic component of the initial part of the designation, identifies the basic design mission of the craft.
- Vehicle Type
- Identifies non-standard vehicle types.
- Design Number
- Serial number assigned to each design of the same mission type, with a dash separating the mission and number.
- A letter suffix to indicate which series within a design the vehicle belongs to.
- Configuration Number
- For missiles and rockets, an identifier to designate specific changes in missile configuration.
- For aircraft, a defined configuration within a series or design.
- Serial Number
- Individual examples have a serial number to identify them.
Status prefix is an optional prefix not often used for vehicles in regular service. If used, it is the first letter in the MDS. Authorized current status prefixes are:
- Captive. Only used for rockets and missiles, C applies to missiles designed to be carried in their launch environment but are incapable of actual launch.
- Dummy. Only used for rockets and missiles which are non-flying, primarily for ground training.
- 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.
- 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.
- 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.
- 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.
- 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.
- Planning. Applied to designs in the planning/pre-development phase.
Modified mission symbols
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 directly in front of the basic mission symbol. Modified mission symbols are not used for rockets and missiles. Currently authorized modified mission symbols are:
- 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.
- Cargo. Similar to the basic mission symbol, C applies to aircraft modified to carry cargo and passengers.
- Director. Applies to aircraft modified to control unmanned aerial vehicles such as drones.
- 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.
- Fighter. Similar to the basic mission symbol, F applies to aircraft modified to engage in air combat. Used on many American fightercraft.
- 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.
- 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.
- 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.
- 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.
- Observation. Applies to aircraft modified to perform observation of enemy or potential enemy positions, and patrol borders or areas of potential infiltration. Example is the OA-10A, an attack aircraft modified to provide observation of enemy territory.
- Patrol. Similar to the basic mission symbol, P applies to aircraft modified to perform maritime patrol.
- 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.
- 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.
- Anti-Submarine. Similar to the basic mission symbol, S applies to aircraft modified to search for, locate, and attack enemy submarines.
- 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.
- Utility. Similar to the basic mission symbol, U applies to aircraft modified to allow use as utility and base support aircraft. Example is the UP-3 Orion, a patrol plane modified for transportation of staff, mail, and operations in support of bases and installations.
- 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.
- Weather. Applied to aircraft modified for weather monitoring and air sampling. Example is the WC-135, a transport modified with special equipment for air sampling. The W designation covers air sampling to detect nuclear, biological, and chemical contamination, and for intelligence gathering on foreign nuclear testing.
Basic mission symbol
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:
- Attack. Attack craft are designed to directly attack enemy land or sea targets, interdict enemy movements and support, and strike precision targets. Examples are the A-6Intruder and A-10Thunderbolt II.
- Bomber. Bombers are designed to attack strategic and tactical targets with heavy bomb loads and missiles. They carry heavy loads of free-fall and stand-off weaponry. Examples are the B-52Stratofortress and B-2ASpirit.
- Cargo. Transports are designed to carry cargo and passengers to provide tactical logistical support and strategic mobility to other forces. Examples are the C-2Greyhound and C-130Hercules.
- Electronic. Electronics craft are designed explicitly to fulfill electronic specialty missions such as ECM, ACC, AEW, and communications. Examples are the E-2Hawkeye and E-3Sentry.
- Fighter. Fighters are designed to intercept and engage enemy aircraft and missiles. It is also a catch-all for multi-mission aircraft, even if it is primarily designed for ground-attack purpose. Examples are the F-22Raptor and F-16Fighting Falcon.
- Airborne Laser. Laser craft are those who are primarily designed to employ laser weaponry against air and ground targets. This is a very new designation, and only applies to the AL-1 ABL program.
- Observation. Observation craft are designed to maintain observation over land, primarily territory either held by enemy forces or susceptible to infiltration. Unlike reconnaissance craft, they loiter over area providing observation over time. Examples are the O-1Bird Dog and OV-10Bronco.
- Patrol. Patrol craft are designed for maritime reconnaissance missions, including anti-submarine warfare. Example is the P-3Orion.
- Unmanned Aerial Vehicles (UAV). Examples are the MQ-1 Predator and MQ-8 Fire Scout.
- Reconnaissance: Reconnaissance craft are designed to conduct reconnaissance through photographic and electrical means. Example SR-71, special or strategic reconnaissance
- Anti-submarine: Anti-submarine warfare (ASW) craft are designed to locate and attack enemy submarines. Example is the S-3Viking.
- Trainer: Trainers are aircraft used to train aircrews. Examples are the T-6 Texan II and T-45 Goshawk.
- Utility: Utility craft are utilized for miscellaneous missions and base support. Example, reconnaissance jet, but for disinformation named UU-2
- Research: Research craft are designed for experimental and developmental research programs. Unlike the X mission modifier, the X basic mission symbol is used for craft solely designed for this purpose, with no operational mission intended or feasible. Examples are the entire series of X-planes from the Bell X-1 on.
Vehicle type 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:
- Glider. A glider is a fixed-wing aircraft designed to use air currents for normal lift, although it may have an engine.
- Helicopter. A helicopter is any rotary-wing aircraft.
- Unmanned. An unmanned aerial vehicle (UAV) is any aircraft without capacity for a human pilot, but not merely a missile or rocket.
- Spaceplane. A spaceplane is a vehicle designed to fly beyond earth's atmosphere and return. This vehicle code was poorly chosen, as it conflicts with the mission code S (Anti-Submarine Warfare). "ES" could equally designate a spaceplane designed specifically for electronic warfare or an anti-submarine plane modified for that purpose.
- V/STOL. A Vertical and/or Short Takeoff and Landing aircraft is designed to take-off and land vertically, but not rely on rotary-wing lift for flight. This includes vectored thrust aircraft such as the AV-8 Harrier and tiltrotors such as the V-22 Osprey. It also applies to aircraft of the normal fixed-wing configuration that are capable of taking off and landing in a short runway space, such as the OV-10 Bronco.
- Lighter than air. A lighter than air craft is designed to remain aloft through buoyancy of lighter than air gases. Such craft include blimps and balloons.
Rocket/missile launch environment
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.
- Air-launched. The missile is launched from an airborne vehicle. Example is the AIM-9 Sidewinderdogfighting missile.
- Multiple. The missile can be launched from various environments. The BGM-109 Tomahawk, for instance, can launch from a ground unit, aircraft, or ship-mounted launcher.
- Coffin. Stored in an unhardened horizontal container (less than 45 degree angle) at ground level and either launched horizontally or raised vertical for launch. Coffin launchers may be either on land or at sea. For an example, see the early versions of the AtlasICBM.
- Individual. The missile is launched by an individual soldier in the field, otherwise referred to as man-portable. Example is the FIM-92Stinger, a light man-portable surface-to-air missile (SAM).
- Ground. The missile is launched directly from the ground surface, including runways.
- Silo-Stored. The missile stored vertically in a silo but raised to ground level for launch. An example is the Atlas-F.
- Silo-Launched. The missile is launched from its storage silo, buried in the ground.
- Mobile. The missile is launched from a mobile ground vehicle.
- Pad. Like a traditional space rocket, the missile is stored and launched from an unprotected ground facility.
- Ship. The missile is launched from a ship or barge.
- Space. The missile is launched from a spacecraft. This is so far used only for the upper stage of another rocket like the SSB-8 Centaur.
- Underwater. The missile is launched from a submarine or underwater device.
Rocket/missile mission symbol
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.
- Transport. Applies to vehicles designed to carry cargo and deliver it to a location. This can also be used to designate a carrier for electronics or weapons systems.
- Decoy. Applies to vehicles that function as decoys for defeating enemy anti-aircraft and anti-missile defenses.
- Electronics. Applies to vehicles that carry out electronic missions such as communications or countermeasures.
- Ground. Applies to vehicles designed to attack surface targets, including vehicles.
- Intercept. Applies to vehicles designed to attack aerial targets, including both aircraft and missiles.
- Launch detection. Applies to vehicles designed to detect launch of missiles and track and identify enemy aircraft and missiles. This also applies to detection and monitoring of space launches and re-entry.
- Scientific. Applies to vehicles designed to collect scientific data.
- Navigation. Applies to navigational assistance designs.
- Drone. Applies to a vehicle designed to be remotely controlled.
- Space support. Applies to vehicles designed to support space programs and activities.
- Training. Applies to training designs.
- Underwater. Applies to vehicles designed to attack submarines and underwater targets.
- Weather. Applies to vehicles designed to obtain weather data and collect aerial samples.
Vehicle type symbol
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.
- Booster. Boosters are primary or auxiliary propulsion units for other vehicles.
- Missile. Guided missiles are unmanned vehicles flying a path controlled by a guidance system.
- Probe. Probes are non-orbital unmanned vehicles designed primarily to collect data within the aerospace environment.
- Rocket. Rockets are single-use unmanned vehicles without guidance after launch.
- Satellite. Satellites are space vehicles which orbit the earth.
- The F/A-18 Hornet uses an unofficial designation to highlight the fact that its multi-role capabilities were built in from the earliest stages (as opposed to a hypothetical AF-18: a fighter modified for the attack role), however other comparable aircraft, such as the F-16 and later F-15s do not seem to have even gained a modified mission A, instead remaining with their F designation. This is the case even with the F-15E Strike Eagle, an F-15 variant used exclusively in the attack role. It should also be noted that the system specifically forbids the use of slashes and other characters, and the Hornet is referred to in official documentation as the FA-18, which implies an attack aircraft modified for the fighter role. The F-22 Raptor was designated "F/A-22" for two years from 2003-2005 before being redesignated F-22 immediately before being transitioned to active service status. A strike version of the F-22 was mooted with the designation FB-22.
- The F-117 Nighthawk has no practical air-to-air capability because several treaties the U.S. signed place restrictions on the addition of new bombers into its military inventory.
- Although the mission letters of the AV-8 Harrier's designation are correct, the series number is not. The Ryan XV-8 ("Fleep") had already existed, so the V designation should have been AV-14.
- The original designation of the SR-71 Blackbird, RS-71 was specifically allowed for in the original system, standing for Reconnaissance and Surveillance - or, it is sometimes said, Reconnaissance and Strike. USAF Chief of Staff Curtis LeMay simply liked the sound of SR-71 better that RS-71, and had the speech changed. The SR was explained as Strategic Reconnaissance.
- The Boeing 747 has three different designations in U.S. service - E-4, (V)C-25 and AL-1 - something which violates the basic purpose of the system.
- The CC-130J Hercules referred to the stretched C-130J-30 Hercules. The -30 suffix was not supportable in the system, so a modified mission letter had to be added. Hence, the CC-130J is a cargo aircraft "modified" for the cargo role. This was later dropped. The CC-130J should not be confused with the CC-130 Hercules operated by the Royal Canadian Air Force. The first "C" identifies the aircraft as a Canadian asset. Canada later acquired C-130Js as CC-130Js.
- Many manufacturers have used non-standard modifiers for commercial purposes; for instance, the Spanish F/A-18 Hornets were 'designated' EF-18 by McDonnell Douglas (the E standing for "España"), and AH-64D Apache helicopters were designated WAH-64 by licensed manufacturerWestland. Non-standard series letters, especially ones the U.S. Air Force has no intention of progressing to, are often used to designate the intended country of use, such as I (Israel - e.g. F-15I), J (Japan), K (South Korea or United Kingdom), S (Saudi Arabia) and SG (Singapore).