The Joint Electronics Type Designation System (JETDS)

To make sense of the alphabet soup that is involved in the systems involved we need to talk about the Joint Electronics Type Designation System (JETDS) that was employed by the Army and Navy starting in 1957.

If we take the AN/APR-24 for an example we can break it down and see what it all means.  The prefix "AN" simply lets us know we are using the 1957 JETDS (AN=Army & Navy) rather than some older designation system. 
  1. In following three letter set the first letter tells us the location of the system - here the "A" tells us we are dealing with a system that is used on a piloted aircraft.  
  2. The second letter tells us the type of equipment - so "P" tells us that we are dealing with some type of radar. 
  3. The third letter tells us the purpose of the equipment - so "R" tells us that the equipment is receiving or passive detecting. 
So APR stands for equipment located on a piloted aircraft, involves radar, and its purpose is receiving or passive detecting.
The numbers are assigned as systems are developed, so it is possible to see a lower number supersede a higher number if the development of a product is protracted.  A good example from the F-4 is when the AN/APR-25 supersedes the AN/APR-30.  So don't always assume that a higher number is better (or newer) than a lower one.
 (For a full list of the letters used in the code see Andreas Parsch's great website - )

Revision History:
  •   17 MAR 2014 - Original Post