United States Tri-Service Aircraft Designation System (Post 1962)

On the 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 U.S. Air Force 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) and 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 (Mission-Design-Series) designation of the form:

Of these components, only the Design Number, Series Letter and Basic Mission are mandatory. In the case of "special" vehicles a Vehicle Type symbol must also be included. The options and usage of each designation elements is discussed below.

(1) Aircraft Status Prefix (Optional)

The status prefix indicates a nonstandard use of an aerospace vehicle, such as test, experimental, prototype, etc. Appears to the immediate left of the modified mission symbol or basic mission symbol for aircraft. Appears to the immediate left of the launch environment symbol or basic mission symbol for rockets and missiles. Example: YF-23A. Status prefix "Y" denotes an F-23A prototype.

Northrop YF-23A "Black Widow II"
"Y" Denotes "Prototype" Status

(2) Aircraft Modified Mission (Optional)

The modified mission symbol identifies modifications to the basic mission of an aircraft. Appears to the immediate left of the basic mission symbol. Example: KC-135E, Modified Mission "K" identifies a C-135E modified for "Tanker".

Boeing KC-135E "Stratotanker"
"K" Denotes "Tanker" Status

(3) Basic Mission (Required)

The basic mission identifies the primary function and capability of an aerospace vehicle and is the initial symbol assigned to that series. For standard vehicles (e.g., bombers, fighters), it appears to the immediate left of the design number separated by a dash. EXAMPLE: F-4B. Basic Mission "F" denotes fighter. For nonstandard vehicles it appears to the immediate left of the vehicle type symbol. EXAMPLE: LGM-118A. Vehicle Type "M" indicates guided missile; Basic Mission "G" indicates surface attack.

McDonnell Douglas F-4B "Phantom II"
"F" Denotes "Fighter" Status

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 Warthog.

(4) Vehicle Type (Nonstandard Vehicles Only - Required)

This is required for nonstandard vehicles, such as helicopter, vertical takeoff and landing (VTOL), UAV control segment, space, etc. A basic mission or modified mission symbol must accompany the vehicle type symbol. Vehicle type appears to the immediate left of the design number, separated by a dash. Example: CH-53E. Vehicle Type "H" indicates a helicopter with a Basic Mission of transport "C".

Sikorsky CH-53E "Super Stallion"
Vehicle Type "H" indicates a helicopter with a Basic Mission of transport "C"

(5) Design Number (Required)

The design number identifies major design changes within the same basic mission. Design numbers run consecutively from "1" to "999" and appears to the immediate right of the basic mission or vehicle type symbols, separated by a dash. EXAMPLE: F/A-18A. Design Number "18" is the 18th MDS requested for an aircraft with a fighter mission under the current MDS reporting system, which was implemented September 1962.

McDonnell Douglas F/A-18A "Hornet"
Design Number "18" indicates the 18th "Fighter" designation

(6) Series Number (Required)

The series number identifies the production model of a particular design number and later models representing major modifications that significantly alter the aerospace vehicle systems components or change of logistics support of the vehicle. Consecutive series symbols, starting with "A", appear to the immediate right of the design number. To avoid confusion, the letters "I" and "O" are not used for this symbol. EXAMPLE: F/A-18E. Series "E" indicates the 5th production model of the F/A-18. At the end of this series indicator "Z", the next sequence will be to advance the design number to the next consecutive unused number and begin with symbol series "A".

Boeing F/A-18E "Super Hornet"
Series Number "E" indicates the 5th production model of the F/A-18

NOTE: The following descriptions for configuration, block, and serial numbers further identify configuration or specific vehicles, but are not part of an MDS designator. DOD 4120.15-L does not contain these numbers. Assignments of configuration, block, and serial numbers do not require coordination with HQ AFMC/LGSI or approval by HQ USAF/XP.

(7) Configuration or Component Number (Optional)

The configuration or component number denotes configuration changes that affect performance, tactics, or integral components of a weapon system that require the same operations or logistics reporting as the aerospace vehicle. Appears to the immediate right of the series symbol, separated by a dash. Each Military Department determines its own method of assigning configuration numbers.

(8) Block Number (Optional)

The block numbers are no longer a required part of the official MDS designation, and their use is optional to the various DOD services. Block Numbers are used for some production aircraft, but not all. Block numbers were introduced by the U.S. Army Air Force in World War II to distinguish between minor sub-variants of a specific aircraft variant. They were originally assigned in steps of five, i.e. 1, 5, 10, 15, ..., with the gaps being intended to be used for modifications after production. This was also the rule for block numbers as defined in the first issue of the current designation system in 1962. The current AFJI 16-401, however, defines block numbers as optional and doesn't state any rules for their actual application. In fact, there are several aircraft types where the block numbers were assigned in strict sequence from 1 up, leaving no gaps. It also seems that the USAF doesn't generally use the "dash-number" nomenclature any more, e.g. the latest B-2A update is generally referred to as "B-2A Block 30" and not "B-2A-30".

Boeing B-52H-135-BW "Stratofortress"
The Block Number is "135"

(9) Manufacturer Code Letters (Optional)

The original designation system as defined in 1962 also mandated the use of a two-letter code suffix to identify the manufacturing plant of an aircraft. Like the block numbers, these code letters were introduced by the USAAF during World War II. However, manufacturers' codes were officially dropped from the regulations in 1976. Therefore they are no longer mandatory, and even their optional use has apparently essentially ceased. The list of code letters as defined in 1962 follows:

McDonnell Douglas F-4C-21-MC "Phantom II"
The Manufacturer Code "MC" indicates that the Aircraft was built by McDonnell Aircraft Corp, St. Louis, MO