thanks for all the replies.
gatbus driver:. Yes, thats exactly how i understand it (on the 75/76)...there is nothing that can happen IN the aircraft to revert to Cat II.
As I have discovered it is only something associated with the airport that could cause cat III to become Cat II during an approach. (stby tx failure?)
Next question...should this still be called a reversion?....or should that term be left to what happens to the aircraft status internally?......am i being a little pedantic now?...it's just that lots of manuals refer to when blah blah fails then "revert" to Cat IIIa (ok with that)..... or CAT II!(hmmm)
vref.