<<If your TCAS issues a RA, Air Traffic Control has already failed.>>
As a retired Heathrow radar controller I take exception to this statement and I am sure that many of my ATC colleagues world-wide will agree that it is flawed.
I have on a number of occasions seen serious incidents caused by TCAS when aircraft started off properly separated. Example: DC-10 was cleared to 4000 ft and pilot announced "TCAS, descending". The only traffic within several miles of that aeroplane was one climbing to 3000 ft underneath. TCAS, not knowing that the outbound was going to stop at 3000 ft and the inbound at 4000 ft had decided that the best action was to get the DC10 down fast - the wrong decision because what was a 100% safe situation developed into a loss of separation.
I have also experienced TCAS RAs causing loss of separation in holding patterns - where an inbound a/c joining a hold is descending rapidly... and also with outbound a/c climbing up rapidly under a holding pattern. Until there is data exchange between the ground and the TCAS such incidents will continue.
TCAS is a most useful tool which has undoubtedly saved lives, but please don't ever in your wildest dreams believe that every RA is caused by an ATC (or aircrew) foul up.
Last edited by HEATHROW DIRECTOR; 2nd July 2004 at 07:35.