1962 United States Tri-Service aircraft designation system

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A pair of armed Phantom jet fighters in flight at high altitude
Before the introduction of the tri-service designation system, the F-4 Phantom II was designated F4H by the U.S. Navy, and F-110 Spectre by the U.S. Air Force.

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.[1]

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.[2]

Designation system[edit]

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).[3]

Status prefix[edit]

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.[4]

Modified mission[edit]

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:

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). Historically, the vast majority of U.S. Coast Guard air assets included the H-code (e.g., HH-60 Jayhawk or HC-130 Hercules). In the 21st century, the Coast Guard has used the multi-mission designation for their armed rescue helicopters (MH-60 Jayhawk or MH-65 Dolphin).[5]

Basic mission[edit]

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"),[6] while a fighter category F incorporates not only aircraft designed primarily for air-to-air warfare, but also multipurpose aircraft[7] designed also for attack missions. The Air Force has even assigned the F designation to attack-only aircraft,[8] 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.[9]

Of these code series, no normal aircraft have been assigned a K or R basic mission code in a manner conforming to the system.

Vehicle type[edit]

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.

Design number[edit]

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[1]) or have kept the design number when they are transferred from one series to another (e.g., the X-35 became the F-35).

Series letter[edit]

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[edit]

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[edit]

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.[10]
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 comes from 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,[11] e.g., YF-113 was a MiG-23.[12]
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.[13]
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.[14]
Proposed tanker based on the Airbus A330 for the KC-X program. This designation skipped 42-44.
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.[15]

Skipped design numbers[edit]

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.[16]

The following table lists design numbers in the 1962 system which have been skipped.

Mission or Vehicle Series Missing numbers Next available number
A 8#, 11, 13 14
B 3-20 22
C 13, 16, 30, 34, 36, 39, 42–44† 47
D (Ground) 5
E 7 12
F 13, 19 24
G 13 17
H (original sequence) 36, 38, 44, 45, 69 74
H (alternate sequence) 7
L 2
O 7
P 1, 6 10
Q 13 28
R 2
S (ASW) 1 4
S (Spaceplane) 2
T (1990 sequence) 2*, 4**, 5** 8
V 13, 14, 17, 19, 21 25
Z 5
*: Skipped to avoid confusion with the North American T-2 Buckeye, which was still in service at the time.
**: The T-4 and T-5 designations were skipped in favor of T-6 by Raytheon to honor the WW2-era North American T-6 Texan.[16] The designations are considered skipped as the sequence continued with the T-7 rather than continuing from the last otherwise sequential designation.
#: A-8 was technically skipped, but the AV-8 Harrier received the number within the "V" sequence.
†: The C-42 through C-44 designations were skipped in favor of the C-45 by Airbus. The designations are considered skipped as the sequence continued in with the C-46 rather than continuing from the last otherwise sequential designation.

Manufacturer's code[edit]

From 1939, a 2-letter manufacturer's code was added to designations to easily identify the manufacturer and the production plant.[17] For example, F-15E-50-MC, the "MC" being the code for the McDonnell Douglas plant at St. Louis, Missouri.

Block number[edit]

In 1941 block numbers were added to designations to show minor equipment variations between production blocks.[18] The block number appears in the designation between the model suffix and manufacturers code (for example F-100D-85-NH).[18] Initially they incremented in numerical order -1, -2, -3 but this was changed to -1, -5, -10, -15 in increments of five.[18] 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.[18] Not all types have used block numbers.

See also[edit]


  1. ^ a b c "DoD 4120.15-L, 'Model Designation of Military Aerospace Vehicles'" (PDF). US Department of Defense. 12 May 2004. Retrieved 2007-01-15.
  2. ^ Designating and Naming Defense Military Aerospace Vehicles, U.S. DoD, 14 March 2005.
  3. ^ "Homepage | FRCWP".
  4. ^ "Current Designations of U.S. Military Aircraft".
  5. ^ 2003 – Airborne Use of Force – Coast Guard Arms HH-65C and HH-60J Helicopters
  6. ^ Designating and Naming Defense Military Aerospace Vehicles (PDF). United States Department of the Air Force. 14 April 2005. Retrieved 29 January 2011. Attack: Aircraft designed to find, attack, and destroy land or sea targets.
  7. ^ 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."
  8. ^ 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.
  9. ^ http://www.navytimes.com/article/20090313/NEWS/903130325/Navy-eyes-Super-Tucano-for-SpecOps-work
  10. ^ De Havilland RC-7B, designation-systems.net.
  11. ^ Patricia Trenner, "A Short (Very Short) History of the F-19". Air & Space Magazine, 1 January 2008.
  12. ^ MiG-23. FAS
  13. ^ Non-Standard DOD Aircraft Designations. designation-systems.net
  14. ^ Jenkins, Dennis R. Lockheed U-2 Dragon Lady, pp. 60–61. North Branch, MN: Specialty Press, 1998. ISBN 1-58007-009-4.
  15. ^ "USAF selects Boeing for KC-X contract". Flight International
  16. ^ a b Parsch, Andreas. "Missing" USAF/DOD Aircraft Designations. designation-systems.net
  17. ^ Andrade 1979, p. 8
  18. ^ a b c d Andrade 1979, p. 9
  • Andrade, John (1979). U.S. Military Aircraft Designations and Serials since 1909. Midland Counties Publications. ISBN 0-904597-22-9.

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