On 18 September 1962, the United States Department of Defense introduced a unified designation system for the aircraft of the United States armed forces. Prior to this date, each service used their own nomenclature system. The 1962 system was based on the one used by the United States Air Force (USAF) between 1948 and 1962. Since it was introduced the 1962 system has been modified and updated; in 1997 a revised form of the system was released. Almost all aircraft operated by the USAF, United States Navy (USN), United States Coast Guard (USCG), United States Marine Corps (USMC) and the United States Army are assigned a designation under this system. Experimental aircraft operated by manufacturers or National Aeronautics and Space Administration (NASA) are also often assigned numbers in the X-series.
The designation system produces an MDS (or Mission-Design-Series) 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 options and usage of each designation elements will be discussed below.
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.
These prefixes are attached to aircraft not conducting normal operations, such as research, testing and development. The prefixes are:
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-13 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.
All aircraft (special and normal) 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., MH-53 Pave Low III). The defined codes are:
Of these code series, no normal aircraft have been assigned a K or R code in a manner conforming to the system. The rise of the multi-role fighter in the decades since the system was introduced has created some confusion about the difference between attack and fighter aircraft. According to this designation system, an attack aircraft is only capable of ground attack missions (e.g., the A-6 Intruder and A-10 Thunderbolt II), while a fighter need only possess minor air-to-air combat capabilities (e.g., the F-111 "Aardvark"). The Air Force prefers to refer to its attack aircraft as "fighter-bombers," thus the F-111 and F-117, which are purely attack aircraft. The only "Attack" aircraft in the USAF's current inventory is the A-10.
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., UC-12). The vast majority of U.S. Coast Guard air assets include the H-code (e.g., HH-60 Jayhawk or HC-130 Hercules).
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).
Since the 1962 system was introduced there have been a number of non-systematic aircraft designations and skipping of design numbers.
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. It should be noted that since the DOD has final authority over its own rules, even non-systematic designations are both correct and official. In other words, even though it uses the system as its guideline for naming aircraft, it can approve whatever it chooses, and whatever is approved is "correct".
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.
The F designation is expected, but the 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. (Such as in EF-111 Raven.)
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. When it was clear that the Lockheed A-12 performance potential was much greater, USAF decided to pursue an RS-71 version of the A-12 rather than the RS-70. However, then-USAF Chief of Staff Curtis LeMay preferred the SR (Strategic Reconnaissance) designation and wanted the RS-71 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.
Seems to use its own two letter basic mission (Tactical Reconnaissance). Later redesignated U-2R after the end of the Cold War.
Skipped hundreds C- series numbers to use the company number, but the letters are expected.
The design number "13" has been skipped in many mission and vehicle series for superstitious reasons. Some numbers were skipped when a number was requested and/or assigned to a project but the aircraft was never built. More information on the reasons behind the apparent skipping of design numbers can be found at Andreas Parsch's "Missing" USAF/DOD Aircraft Designations page.
The following design numbers in the 1962 system have been skipped:
|Mission or Vehicle Series||Missing numbers||Next available number|
|A||8, 11||13 or 14|
|C||16, 30, 34, 36, 39, 42–44||46|
|F||19, 24–34||24 or 36*|
|H||42, 49, 69||73|
|K||n/a (K series was cancelled)|
|S (Spaceplane)||Possibly 2|
|T||4, 5, 50||52|
|U||12, 14, 15||29|
|V||14, 17, 19, 21||24|
|X||23, 39, 52||55|
24 or 36 depends on future aircraft designations of the DoD.