I think the letters are just the military phonetic alphabet, not sure if that is just a US thing or not. I know law enforcement has their own version, Adam, Boy, Charlie, David etc vs Alpha, Bravo, Charlie, Delta etc, so it wouldn't surprise me if other nations also had their own.
Nevermind, wikipedia to the rescue, that is the NATO phoenetic alphabet. Kind of neat entry as they give earlier nation specific alphabets in addition to the current NATO version, also several other varieties.
In WW2 the British would have called your HUEY the pip, in WW1 it would have been a pudding .
http://en.wikipedia.org/wiki/NATO_phonetic_alphabet