On September 18, 1962, the existing aircraft designations of the US Army, US Navy and US Air Force was unified. This new system would replace a bewildering array of mission designations, manufacturer codes and modification suffixes varying from service to service. These new reference codes that would be applied to all existing and future US military aircraft became known as the "Mission, Design, Series" designator (MDS). The MDS is also used for space weapons and electronic equipment but are not covered here.
The MDS is built from 1 to 4 letters, a hyphen, a number and usually another letter. Example: EF-111A. Because our brains works the way they do, an official nickname are also given to most aircraft. The EF-111A was named "Raven" and was a heavily modified version of the F-111 Aaardvark. Not all aircraft get official nicknames, and some aircraft get unofficial nicknames that completely precludes the official one. A very good example here is the A-10 Thunderbolt II. Nobody calls the A-10 by its given name, not even the top brass in Pentagon I'm sure. And since you probably wonder, the unofficial name is "Warthog" or simply "the Hog". After Desert Storm, A-10 pilots (or, if you will, Hog drivers) had accomplished all sorts of more or less impossible feats, leading to the pilots themselves jokingly referring to their aircraft as "RFOA-10G Warthog". You will probably understand more of this hardcore in-joke after reading through all of this.
The letters to the left of the hyphen in the MDS means the following:
Status Prefix designator
- G - Grounded Permanently
- J - Special Test (temporary)
- N - Special Test (permanent)
- X - Experimental
- Y - Prototype
- Z - Planning
Modified Mission designator
- A - Attack
- C - Cargo/Transport
- D - Drone Director
- E - Special Electronics Installation
- F - Fighter
- H - Search and Rescue (SAR)
- K - Tanker
- L - Polar
- M - Missile-carrier
- O - Observation
- Q - Drone
- R - Reconnaissance
- S - Anti-submarine
- T - Trainer
- U - Utility
- V - Staff/VIP
- W - Weather
Basic Mission designator
- A - Attack
- B - Bomber
- C - Cargo/Transport
- E - Special Electronics Installation
- F - Fighter
- K - Tanker
- L - Laser
- O - Observation
- P - Patrol
- R - Reconnaissance
- S - Anti-submarine
- T - Trainer
- U - Utility
- X - Research
Vehicle type
The number
To the right of these letters now comes a hyphen and a number. The number denotes a major design change for the Basic Mission category. In other words, this is the '15' in F-15. The numbers does not follow any premeditated pattern, and a lower number does not mean the design is older than an aircraft with a higher number. A good example here is the B-2 Spirit and the B-47 Stratojet. The former was deployed in 1993 and the latter was taken out of service in the early 1960's.
At the end of the MDS is the design modification letter. This denotes any minor changes on the design. The letters start with 'A' and progresses alphabetically. Letters 'I' and 'O' are not used to avoid confusion with the numbers one and zero.
How it might look
Let us take a look on how an aircraft might be designated in real life. In order to do that, we need an aircraft with lots of letters. Let's do the YAL-1A. This very special aircraft started its life as a freighter version of the famous Boeing 747; a 747-400F. The US government got hold of one of these and started building a prototype out of it. Its intended use is beyond the scope of this writeup, but feed YAL-1A into your favourite search engine and see what you can find.
Basic Mission: Laser -----------------+
|
Modified Mission: Attack -----------+ |
| |
Status: Prototype ----------------+ | |
| | |
| | |
Y A L - 1 A
| |
Major Design number ----------------------+ |
|
Modification (here: none) ------------------+
So what we actually got here is the prototype of an airborne attack laser. I bet you didn't know they were up to such things.
The anomalies
As a rule, there is no rules without exceptions. That rule applies for the US Department of Defense as well, so here is a list of aircraft that somehow got their designations messed up. These are designations that are either nonsensical, reuse previously assigned numbers or are out of sequence. Not that it matters though.
- AV-8 Harrier. Reused V-8 designation.
- DeHavilland RC-7B. An error by the US DoD. The RC-7B and the C-7A are both in service and are two completely different aircraft.
- CC-130J Hercules. The CC designator is not covered by the MDS.
- F/A-18 Hornet. There's no 'F/A' mission designator.
- F-35 Joint Strike Fighter. Not a formal designation, and might even change before long. If used, it will be out of sequence.
- FB-111 Aardvark. Strategic bomber version of the F-111. Should really have been BF-111 under the MDS.
- SR-71 Blackbird. 'SR-71' is actually a continuation of the pre-1962 designations given to bombers. The B-70 Valkyrie was intended to become the RS-70 and do reconnaisance and strike - hence 'RS'. The post-1962 MDS version of 'RS' means "Reconnaissance and Anti-Submarine", but in the original 1962 documents on MDS, RS-70 was explicitly stated as a special case. Before the B-70 could be made into the RS-70 however, it became clear that CIA's A-12 had a much better performance, and the USAF version of the A-12 was going to be designated RS-71, still a special case on the MDS. General Curtis LeMay, then USAF Chief of Staff didn't like this designation and had president Lyndon B. Johnson's public announcement on the Blackbird changed, reading 'SR-71' everywhere instead of 'RS-71'. And so the SR-71 Blackbird got it's designation.
- AL-1 Airborne Laser. There was no 'L' in the Basic Mission designator until this aircraft came along. Although technically wrong, the L-designator sort of snuck in anyway.