UNCTUOUS
I don't really understand your thinking. What we are trying to prevent is the scenario described in Japan. There have now been quite a few very serious incidents where ATC and TCAS avoiding action have been contradictory.
If you ever get the chance to see an ATC radar recording and a TCAS RA recording at the same time the time difference between displaying the same event is quite unnerving because of time lag.
It is not going to be any spy vs spy system because, certainly in the UK, ATC are clearly instructed that when a pilot announces RA action we give no more instructions. What this might do is -
1. Stop the contradictory avoiding action instructions.
2. Allow ATC to be aware of the RA and give relevent traffic information (not all aircraft are SSR never mind TCAS equipped)
3. Allow ATC to try to stop the "domino" effect of TCAS RA setting of more TCAS RAs, by seeing the RA instruction and trying to move potential 3rd party conflictions out of the way so they do not become involved.
The only possible drawback to this is the speed at which it can be displayed to ATC and the time taken assimilate the information and act upon it, possibly in a busy ATC environment. At worst it should merely add to the information available to all parties.