USAAC/ USAAF/ USAF Aircraft Designation Systems

History of Air Force Names
Prior to 1919-1920
1919-1924 USAAS System
1924-1962 USAAS/ USAAF/ USAF System
1962 Tri-Service Aircraft Designation System
Shared Features
Type Lists
Lists for shorter sequences

The US Air Force and its predecessors have used a series of designation systems to identify their aircraft, starting by using the manufacturer's own codes then adopting a system of type numbers and two letter codes in 1919-20. This was replaced by the more familiar basic mission system in 1924, with single letters for most aircraft types. This remained in use (with variants) until 1962, when it became the basis of the current Tri-service aircraft designation system.

History of Air Force Names

Unfortunately these changes in designation system don't neatly match the periodic changes in the name and status of the air force. During the First World War the Army's aviation was controlled by the Air Service (USAAS). The Air Service outlived two designation systems - the original system using manufacturer's own names and codes and the first organised system of 1919-1924. The Air Service was still in existence when the 1924 designation system was introduced.

In 1926 the United States Army Air Corps was formed (USAAC). This organisation inherited the Air Service designation system of 1924. Very few changes were made during the Air Corps period. Manufacturer codes were added in 1939 and a number of new basic mission types were introduced.

In 1933 GHQ Air Force (Provisional) was formed. This unit sat alongside the Air Corps in the Army system, and had operational control of air units based within the Continental Air Force. This meant that Army aviation had no single head of service.

In 1941 the United States Army Air Force was formed (USAAF). This sat above the Air Corps and GHQ Air Force (which became Air Force Combat Command). General Henry 'Hap' Arnold, then the head of the Air Corps, became the first head of the USAAF. Air Force Combat Command only lasted until 1942 while the Air Corps remained in existence until 1947, but lost most of its significance. The new USAAF inherited the existing USAAC designation system. A few minor changes were made during the USAAF period, mainly the introduction of a large number of new aircraft types (mainly gliders) and the introduction of block numbers.

In 1947 the Air Force finally became an independent service, as the United States Air Force (USAF). Once again the existing designation system was inherited. A number of changes were made in 1948, including the change from P for Pursuit to F for Fighter and the creation of a consolidated T for Trainer class (replacing AT, BT and PT) and a consolidated G for Glider class.

Prior to 1919-1920

Before 1920 the USAAS simply used the manufacturer's own names for their aircraft. A number of European-manufactured or designed aircraft were used during this period, while amongst the most famous American aircraft were the Curtiss JN-4 'Jenny' and the Thomas Morse MB-3 Scout.

Partial List of early USAAS Aircraft

Curtiss NC-4

Curtiss JN-3
Curtiss JN-4 'Jenny'

Martin MB-1
Curtiss-Martin MB-2 (NBS-1)

Thomas Morse MB-1
Thomas Morse MB-2
Thomas Morse MB-3 Scout
Thomas Morse MB-6

1919-1924 USAAS System

In 1919 the USAAS adopted its first organised designation system. The first version of this system consisted of fifteen numerical types (using Roman numerals). Each of these was associated with a two or three letter abbreviation of the type name. This is often described as a type and engine cooling system (PW being Pursuit, Watercooled), but this wasn't the case. Only four of the original fifteen codes match this pattern (PW, PA, TW and TA), and the codes were simply abbreviations of the full description. A further eight types were added to this system before 1924, none of which gained type numbers (or match the type, engine cooling system). As in all later systems each aircraft within a type received a number, starting from one. None of these numbered sequences reached double figures, and the Boeing PW-9 received the highest number).

I PW Pursuit, Watercooled
II PN Pursuit, Night
III PA Pursuit, Aircooled
IV PG Pursuit, Ground Attack
V TP Two-seat Pursuit
VI GA Ground Attack
VII IL Infantry Liaison
VIII NO Night Observation
IX AO Artillery Observation
X CO Corps Observation
XI DB Day Bombardment
XII NBS Night Bombardment - Short Distance
XIII NBL Night Bombardment - Long Distance
XIV TA Trainer, Aircooled
XV TW Trainer, Watercooled
- A Ambulance
- G Glider
- LB Light Bomber
- M Messenger
- PS Alert Pursuit (Special)
- R Racer
- S Seaplane
- T Trainer

Bombers fell slightly outside the main scheme. Three bomber types were included in the 1919 system - Type XI for Day Bombardment (DB), Type XII for (NBS) and Type XIII for Night Bombardment - Long Distances (NBL). In 1923 the DB type became the Light Bombardment (LB). Heavy Bombardment (HB) followed in 1925, but only survived for a year. 1926 saw the adoption of a unified designation system for bombers, beginning with the Huff-Daland (Keystone) XB-1. A further classification - Bomber Long Range or BLR was briefly introduced in 1935-36, but only three aircraft entered that series.

LB - Light Bomber
NBL - Night Bombardment, Long Distance
NBS - Night Bombardment, Short Distance

Full List of Aircraft under 1919-1924 System

1924-1962 USAAS/ USAAF/ USAF System

In 1924 the system was modified. The new system had a one or two letter Mission Letter, and a single letter prefix that indicated the status of a particular aircraft. As with the 1919-24 system each mission type got its own numerical sequence. At first PW and LB survived from the old system, but they disappeared as the last aircraft in each class left service. In its earliest version the system had a limited number of types (O and A in 1924, HB, AT, OA, P, PT and C in 1925 and the unified B for Bomber sequence from 1926), but the number soon expanded.

The new system included a status prefix that was normally applied to individual aircraft (indicating if the aircraft was Grounded, eXperimental or a service test aircraft (Y).

In 1943 a second prefix, for mission modifier, was added. This was used when an aircraft was being used for a different role to its original purpose. C for Cargo, T for trainer and U for utility (or light transport) were introduced in 1943, but once again the system soon expanded.

Eventually the full designation of an individual aircraft could consist of NN parts:

<status prefix> <mission modifier> <main mission> - <series number> <sub type> - <block number> - <factory>

A RCB-24J-10-CF would thus be a restricted use B-24J bomber from production block 10 at Consolidated Fort Worth, being used as a cargo aircraft. In standard use most of these details are omitted and the aircraft would be seen as a B-24J.

Mission Letters

The main mission was indicated by a one or two letter code.

A - Attack (to 1947)
A - Amphibian (from 1948)
AG - Assault Glider
AT- Advanced Trainer
B - Bombardment
BC - Basic Combat
BG - Bomb Glider
BT - Basic Trainer
C - Cargo (also as mission modifier)
CG - Cargo Glider
CO - Corps Observation
F - Fighter (from 1948)
F- Photographic (to 1947) (also as mission modifier)
FM - Fighter, Multiplace
G - Glider (from 1948)
H - Helicopter (from 1948)
HB - Heavy Bomber (to 1927)
L - Liaison
LB - Light Bomber (to 1932)
O - Observation
OA - Observation Amphibian
P - Pursuit
PB - Pursuit, Biplace
PT - Primary Trainer
R - Reconnaissance (from 1948) (also as mission modifier)
R - Rotary Wing (1941-47)
T- Training (also as mission modifier)
TG- Training Glider
U - Utility (also as mission modifier)
V - VTOL or STOL
X - Special Research

The three training types (BT, PT and AT) were replaced by T in 1948 with the numbers following on from the primary trainers. The PT-27 was thus followed by the T-28. 1948 also saw the various glider classes were consolidated as the G glass and P for Pursuit became F for Fighter.

Status Prefix

Most status prefixes were a single letter and indicate either a restriction on an individual aircraft or its status as a development aircraft. The Y1 code was an exception and indicated an aircraft with non-standard funding.

R - Restricted
X - Experimental
Y - Service test
Y1 - Funded from outside the normal sources.
Z - Obsolete

The prefixes were normally attached to individual aircraft, although entire types could be designated as Restricted or Obsolete. Aircraft that didn't enter production are normally known by whichever of the X or Y designations they reached, such as the Wedell-Williams XP-34 or the Curtiss YP-37.

Mission Modifier

The mission modifier was a single letter, and was similar to the main list with the following extra codes.

K - Tanker
M - Medical
P - Passenger transport only
Q - Radio controlled drone
R - Photographic Reconnaissance
S - Search and Rescue
V - VIP Transport
W - Weather

1962 Tri-Service Aircraft Designation System

In 1962 the separate Army, Navy and Marine Corps systems were replaced by the Tri-Service Aircraft Designation System, which was a slightly modified version of the previous USAF system. The main mission code was replaced by a basic mission code, and the number of mission types was greatly reduced. Some sequences started again from one, with existing Navy aircraft getting the first new codes (existing Air Force aircraft kept their original designation). Other types retained their existing sequence, most notably helicopters (see below for more details).

Training aircraft started from one in 1962, but only two new designations were issued, for the T-1 SeaStar and T-2 Buckeye, both existing Navy types. The T sequence started again in 1990, but only the T-1, T-3 and T-6 have been used (T-2 was skipped because the Buckeye was still in use).

The F for Fighter sequence started again with Navy aircraft getting new codes. It then continued to the F-23, before going rather haywire. The X-35, which should have become the F-24, instead became the F-35 while the Lockheed F-117 Nighthawk used a number that appears to have been allocated to it during its testing process.

Sub-type letters, block codes and manufacturer codes are used in the 1962 system just as in the previous system, so the format for fixed wing aircraft is

<status prefix><modified mission prefix><basic mission>-<sequence number><subtype>-<block><manufacturer>

Other types of aircraft have a aircraft code type, so their full designation can reach

<status prefix><modified mission prefix><basic mission><aircraft type> -<sequence number><subtype>-<block><manufacturer>

An example of this would be a Boeing-Sikorsky XRAH-66 Comanche, which would be an experimental prototype of a Reconnaissance/ Attack Helicopter, sixty sixth in the helicopter sequence. Three letter codes aren't common with helicopters, and instead the mission letter is changed, so the H-46 is operated as the CH-46 Sea Knight, UH-46 utility transport and the HH-46 search and rescue helicopter

As with the 1924 system this is often reduced to <basic mission>-<sequence number><subtype> (B-52H Stratofortress); <modified mission prefix><basic mission>-<sequence number><subtype> (KC-10A Extender) <basic mission><aircraft type> -<sequence number><subtype> (AH-64B Apache)

Basic Mission Letter

At the heart of the 1962 system is the Basic Mission letter.

A - Attack
B - Bomber
C - Transport
E - Special Electronic Installation
F - Fighter
K - Tanker (used as secondary designation)
L - Laser-equipped
O - Observation/ Forward Air Control
P - Maritime patrol
R - Reconnaissance (used as secondary designation)
S - Anti-submarine warfare
T - Trainer
U - Utility
X - Special research

Status Prefix

There are two sets of prefixes in use - a status prefix and a modified mission prefix. The status prefix (if any) goes first and is similar to the earlier system.

G - Permanently ground
J - Temporary special test
N - Permanent special test
X - Experimental
Y - Prototype
Z - Planning

Modified Mission Prefix

The modified mission prefix goes next, between the status prefix (if any) and the basic mission. Most basic mission letters can also be used as modified mission prefixes (most common with K for tanker, which so far has only been used in this way). There are also a number of specific modified mission prefixes which are not used as basic mission codes.

D - Drone Director
H - Search and rescue, MEDEVAC
L - Cold weather
M - Missile carrier to 1972, mine countermeasures 1973-76, Multi-mission 1977 to now
Q - Unmanned drone
V - staff transport
W - weather recon

An aircraft with the designation XAC would this be an eXperimental Attack Cargo aircraft (AC is a fairly common combination used on many gunships). Most Reconnaissance aircraft are also modifications of other types, as in the Douglas RB-66 Destroyer.

Aircraft Type Code

The basic mission code can also be followed by an aircraft type code.

D - Unmanned aerial vehicle
G - Glider
H - Helicopter
Q - Unmanned aerial vehicle
S - Spaceplane
V - VTOL/ STOL
Z - Lighter than air

Shared Features

Sequence Number

In most cases each basic mission type has its own numbered sequence, most of which restarted from 1 in 1962. If the aircraft has a type suffix then the sequence follows that letter instead. This is best seen in the helicopter sequence, where Attack Helicopters (AH) and Utility Helicopters (UH) share the same numerical sequence (which didn't restart in 1962).

Manufacturer Codes

In 1939 manufacturer codes were introduced to cope with the problems caused when an aircraft type was produced by more than one company. This became more significant as the speed of production increased, and some aircraft were produced by several factories. The two letter codes also distinguished between different factories, so CO was Consolidated, San Diego while CF was Consolidated, Fort Worth. This system became part of the 1962 designation system

Model Codes

Both the 1924 and 1962 systems use model letters to distinguish between different versions of the same aircraft. Sometimes the changes were fairly minor, but in some cases they were quite significant (as with the introduction of the Rolls-Royce Merlin engine on the P-51B Mustang.

Block Numbers

In 1941 block numbers were added to the model codes, in an attempt to keep pace with the many minor variations being introduced. Block numbers were specific to each aircraft, manufacturer and model, so features introduced on a B-24J-10-CF might not appear on a B-24J-10-CO. At first the block number increased in steps of one (-1, -2, -3 etc), but this was then changed to blocks of five (-1, -5, -10 etc), with the intervening numbers used for modifications in the field. Some changes in block numbers marked quite significant changes (new types of gun turrets or engine variant) while others were very minor (changes to electrical equipment etc). Block numbers are part of the 1962 system.

Type Lists

Attack (A)
Bombers (B, HB, LB, BLR)
Cargo Aircraft (C)
Gliders (G, AG, BG, CG, FG, PG, TG)
Fighters (P, F)
Helicopters (R, H)
Reconnaissance (F, R)
Observation/ Liaison (O, L, OA)
Trainers (AT, BT, PT, T)
Utility (U)
X-Planes (X)

Lists for shorter sequences

BC - Basic Combat

North American BC-1 basic combat/ combat trainer
North American BC-2
Vultee BC-3

E -Special Electronic Installation

Grumman E-1 Tracer (WF-2)
Grumman E-2 Hawkeye
Boeing E-3 Sentry
Boeing E-4 Nightwatch
Windecker Industries E-5 Eagle
Boeing E-6 Mercury
E-7 allocated to EC-18B
Boeing/ Grumman E-8 J-STARS
de Havilland Canada E-9 Widget
Boeing Northrop Grumman E-10 MC2A
Bombardier Northrop Grumman E-11
Boeing E-767

P - Patrol (post 1962)

P-1 skipped
Lockheed P-2 Neptune
Lockheed P-3 Orion
Consolidated P-4 Privateer
Glenn L Martin P-5 Marlin
P-6 skipped
Lockheed P-7
Boeing P-8 Poseidon

S (post 1962)

S-1 not used
Grumman S-2 Tracker
Lockheed S-3 Viking

V - Convertiplane

McDonnell XV-1
Sikorsky XV-2
Bell XV-3

V - VTOL/ STOL

Grumman OV-1 Mohawk
de Havilland Canada V-2 Caribou
Bell V-3
Lockheed V-4 Hummingbird
Ryan V-5 Vertifan
Hawker Siddeley V-6 Kestrel
de Havilland Canada V-7 Buffalo
Ryan V-8 Fleep
McDonnell Douglas/ BAe AV-8 Harrier
Hughes V-9
Rockwell OV-10 Bronco
Parsons V-11 Marvel
Parsons V-12
Rockwell V-12
V-13 not used
V-14 not used
Bell V-15
McDonnell Douglas BAe V-16 Advanced Harrier
V-17 skipped
de Havilland Canada V-18 Twin Otter
V-19 skipped
de Havilland Canada V-20 Chiricahua
Airship Industries V-21 PACES
Bell V-22 Osprey
Dominion V-23 Scout

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How to cite this article: Rickard, J (30 November 2012), USAAC/ USAAF/ USAF Aircraft Designation Systems , http://www.historyofwar.org/articles/weapons_USAAF_aircraft_designations.html

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