This comes from the TERPs, and applies to all approaches, not only military
approaches:

"Where more than one approach using the same final approach guidance is
developed to the same runway, identify each for the runway/navigational aid
combination with alphabetical suffix beginning at the end of the alphabet;
e.g., ILS Z RWY 28L (first procedure), ILS Y RWY 28L (second procedure), ILS
X RWY 28L (third procedure), etc."

Bob Gardner

"Andrey Serbinenko" wrote in message
...

After looking at the ILS-Z approach in NC that was discussed here some
time
ago, I was curious how many similar approaches there are, and if they all
are military. Thanks to the uniform naming NACO uses for its chart files,
it was fairly easy to get a list of all the ILS-Z approaches: there aren't
that many, probably a dozen, and all of them are military -- usually there
would be two -- a Z GPS approach, and a Y RNAV counterpart.
But for one place:
http://www.naco.faa.gov/d-tpp/0610/00641IY12.PDF
There's only ILS-Y approach here, and no Z approach. Does anyone know
why there's no Z?


Andrey