1962 United States Tri-Service aircraft designation system

thumb|upright=1.5|alt=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. Previously, 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 (USA), United States Space Force (USSF), 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.

Status prefix

These optional prefixes are attached to aircraft not conducting normal operations, such as research, testing and development. The prefixes are:

Modified mission

Aircraft which are modified after manufacture or even built for a different mission from the standard airframe of a particular design are assigned a modified mission code. They are:

Basic mission

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: 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 aircraft in the U.S. Navy and U.S. Marine Corps was the A-6 Intruder, with the only strictly A designated fixed-wing aircraft remaining in the sea services being 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.

Vehicle type

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:

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.

A-29

:Briefly designated "A-14A" before being changed to "A-29B" to match the Brazilian designation.

A-37 Dragonfly

:Used the design number from its parent aircraft, the T-37 Tweet, rather than the next available number in the A series (A-8). Initially designated as the YAT-37D, using an A mission modifier and D series letter that continued the T-37 sequence, but redesignated as the YA-37A during development.

B-21

:Designated "B-21" as being the first bomber type of the 21st century, rather than the next available number in the B series (B-3).

E-130J

:Uses both the design number and suffix letter from its parent type, the C-130J Hercules, rather than the next available number in the E series (E-12).

EA-37B

:Redesignated from EC-37B to better reflect the aircraft's capabilities. The new designation conflicts with the A-37B Dragonfly.

F/A-18 Hornet, also the transient F/A-16 and F/A-22.

: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 despite the designation system not allowing for slashes or other characters. AF-18 would be conformant. Similar issues existed with the naming of the F-22, which was briefly redesignated F/A-22; a proposed bomber variant was the FB-22 (which, more appropriately, should have been designated BF-22). e.g., YF-113 was a MiG-23. Additionally, the basic mission designation as fighter implies air-to-air capabilities though the F-117 does not possess any. There have been conjecture and anecdotal reports concerning purported air-to-air capabilities for use against Soviet AWACS craft.

RC-7B

:Designation conflicted with unrelated C-7 Caribou. Was redesignated EO-5C in August 2004.

SR-71

: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 the Lockheed A-12 which was dubbed RS-71 (Reconnaissance/Surveillance; unrelated to the S mission designation for anti-submarine warfare). Then-USAF Chief of Staff Gen. Curtis LeMay preferred the SR (Strategic Reconnaissance) moniker 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.

TR-1

:A variant of the U-2; uses its own modified mission letter (T for Tactical) with basic mission letter (R for Reconnaissance). The U-2 was initially designated as "utility" to obfuscate its reconnaissance capabilities. Following shootdowns of the aircraft, this subterfuge was pointless. The TR-1, first flown in 1981, was re-designated U-2R in 1991 for uniformity.

Historical Designation Re-use: Several aircraft have received non-systematic designations as tributes to retired historically significant aircraft.
F-47: Boeing developed sixth-generation fighter aircraft. Designation was chosen as a tribute to the Republic P-47 Thunderbolt, the USAF's founding in 1947, and in recognition of the support of Donald Trump—the 47th President of the United States—for the project.
The P-47 was re-designated as F-47 in 1947 when the pursuit (P) designation was replaced by fighter (F).
The Fairchild Republic A-10 Thunderbolt II also pays tribute to the P-47.
OA-1K Skyraider II: Designated to "[renew] the rugged and versatile nature" of the long-retired and unrelated A-1 Skyraider, of which the A-1J was the last production variant, rather than using the next available number in the A series (14).
T-6 Texan II: Turboprop training aircraft. Design numbers 4 and 5 of the Training vehicle type were skipped in order to pay tribute to the earlier North American T-6 Texan.

Civilian model number usage: Numerous series numbers have been skipped to use civilian model numbers.
KC-767: 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.
MH-90 Enforcer: armed version of the MD 900 and MD 902 for the United States Coast Guard. Flown by the Helicopter Interdiction Tactical Squadron between 1998 and 2000.
MH-139 Grey Wolf: security and support missions variant of the AW139 for the United States Air Force.
TH-66 Sage: military training variant of the Robinson R66 for the U.S. Army FAA Part 141 Helicopter Flight School Pilot Program. Aircraft shares the same vehicle type and design number (H-66) as the Boeing-Sikorsky RAH-66 Comanche.
UC-880: aerial tanker variant of the Convair 880 operated by the United States Navy.
VH-92: presidential transport variant of the Sikorsky S-92 operated by the United States Marine Corps.

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 which have been skipped.

{| class="wikitable" valign="top"

!Mission or Vehicle Series

!Missing numbers

!Next available number

|8<sup>#</sup>, 11, 13

|14

|3–20

|22

|13, 16, 30, 34, 36, 39, 42–44†

|47

|D (Ground)

|12

|13, 19‡

|24

|13

|18

|H (original sequence)

|36, 38, 44, 45, 69

|74

|H (alternate sequence)

|1, 6

|10

|13

|31

|S (ASW)

|S (Spaceplane)

|T (1990 sequence)

|2*, 4**, 5**

|13, 14, 17, 19, 21

|26

: <nowiki>#</nowiki>: A-8 was technically skipped, but the AV-8 Harrier received the number within the "V" vehicle type sequence. Within the V sequence, it should have been designated AV-12 (as the Ryan XV-8 "Fleep" was already in existence). Additionally, the stillborn 1960s General Dynamics Model 100 attack aircraft proposal has been referred to as the A-8A, but it is unclear if it was ever formally granted this designation by the USAF.

:†: The C-42 through C-44 designations were skipped in favor of the KC-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.

: ‡: A top-secret stealth fighter designated F-19 has been rumored to exist for decades, and the rumors gained widespread publicity after the USAF cordoned off a crash site near Nellis Air Force Base in July 1986, but the crashed aircraft was subsequently revealed to have been an F-117, which was still classified at the time. No conclusive evidence of a genuine F-19 program has surfaced.

: *: 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.

References

Citations

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General and cited references

External links

U.S. Military Aviation on Designation-Systems.net by Andreas Parsch—a reference source with details, examples and history
Non-standard designations page on Designation-Systems.net
Designation Systems FAQ on hazegray.org by Emmanuel Gustin
U.S. Military Aircraft Designations 1911–2004 on driko.org by Andrew Chorney
U.S. Military Aircraft and Weapon Designations by Derek O. Bridges