AIP is pretty clear - it doesn't allow abbreviation of the standard 3-letter callsigns for Australian registered aircraft operating in the Australian FIR "unless conforming with an approved alternative format" - GEN 3.4-20, 4.19.4.
If the pilot wishes to use an "approved alternative format" such as Triple Fox then maybe he should plan it either in the ACID if it fits or Field 18 if it won't.
Until he does that, in my opinion the callsign has to be Alpha Alpha Alpha or Foxtrot Foxtrot Foxtrot, etc.
What liberties people allow themselves is a different matter.
Agree with you 135.9 re slick callsigns. Either get a good one or get an approved alternative.
[This message has been edited by Ausatco (edited 13 September 1999).]