US Tri-Service Aircraft Designations

In 1962, the US Military adopted the so-called "Tri-Service" designation system, which is still used today. Under the system, the three services (USAF, USN and USMC) were to use common designations for aircraft, guided missiles and electronic equipment. The conventions are described in the DEPARTMENT OF DEFENSE PUBLICATION 4120.15-L and are officially known as the MDS (MISSION, DESIGN, AND SERIES SYSTEM). Below are the details of the designation system for aircraft:

General Format

A typical aircraft designation has the following format:

with X denoting an arbitrary letter and the hash-mark an arbitrary digit. Not all letters or digits are necessarily used. All characters have a special signification, according to their position in the designation (The numbers of the sections below correspond with the numbers in the figure above):

1. Status Prefix (Rarily Used)

Indicates any special modifications that have been made to the aircraft.

Status Prefixes

Prefix	Status
G	Permanently grounded
J	Special Test Temporary
N	Special Test Permanent
X	Experimental
Y	Prototype
Z	Planning

2. Modified Mission

Indicates the vehicle has been modified for a specific mission. Only one modified mission symbol is allowed. The modified mission symbol precedes the basic mission symbol.

Launch Environment

Prefix	Launch Environment
A	Attack
C	Cargo / Transport
D	Drone control
E	Special electronic installation
F	Fighter
H	Search and Rescue (SAR)
K	Kerosine Tanker
L	Cold-weather
M	Multi-mission
O	Observation
P	Patrol
Q	Drone
R	Reconnaissance
S	Anti-Submarine Warfare (ASW)
T	Trainer
U	Utility
V	Staff/ VIP transport
W	Weather

3. Basic Mission

Indicates the primary task for which the aircraft was designed.

Basic Mission

Prefix	Basic Mission
A	Attack
B	Bomber
C	Cargo / Transport
E	Special electronic installation
F	Fighter
O	Observation
P	Patrol
R	Reconnaissance
ER	Electronic Reconnaissance
SR	Strategic Reconnaissance
TR	Tactical Reconnaissance
S	Anti-Submarine Warfare (ASW)
T	Trainer
U	Utility
X	Research

4. Vehicle Type

Indicates the type of vehicle at hand, e.g. helicopter, V/STOL. For normal aircraft, this designator is NOT used.

Vehicle Type

Prefix	Vehicle Type
G	Glider
H	Helicopter
S	Spaceplane
V	VTOL/STOL
Z	Lighter than air

5. Design Number

Indicates the model of the vehicle within the basic mission category. Supposedly in sequential order, but the sequence contains gaps: F-14, F-15, F-16, YF-17, F-18, F-20, F-22, X-29, F-35, etc.

6. Series

Indicates (alphabetically) major modifications to the original design, which is indicated by the A. I and O are usually skipped in order to avoid confusion with the 1 and the 0. For example, the F-16B is a two-seat version of the F-16A.

7.Block Number

Indicates a minor modification within the series. e.g. The first F-16A/Bs were block 1 aircraft, after minor engineering modification they became block 5, then block 10, etc. Note: For the F-16, Block numbers are usually written in full, for example F-16C block 40, rahter than F-16C-40.