ICAO Codes ---> No lead I, J, Q, or X. Why not?

In ICAO codes, 22 of 26 letters are represented as lead letters to denote a certain section or country in the world. But the above letters in my post title are omitted. Why is that?

 

-- John

You'd probably have to ask whoever assigned those codes. I doubt those ICAO folks are on this forum.

I'm guessing the EULA on those letters may have been questionable so they opted not to use them. :)

Well, I did a little more research, and I think I may have found answers that explained three of the four lead letters:

 

"Q" is reserved for international radio communications, and they may not wish to confuse radio call letter assignments with airport assignments.

 

"X" is used for government, experimental aviation, and military uses in Russia. And although that use seems to be limited to that one country, they may feel it best to avoid it altogether on an international nomenclature system.

 

"I" I believe is used to name call letters on aviation beacons or radio identifiers? VOR's DME's? Whatever those things are called. So they don't want to mix up airport ID's with one of those.

 

And finally. "J"? I couldn't find any answers on that one, despite an hour of Googling and hunting around the internet. However, I did email the FAA to see if anyone there can answer my question. I have a feeling if anyone knows, they will.

 

-- John

Thanks, good question, & interesting answers, for something we take for granted.