lost the picture
Good points well made.
I think from re-reading the posts we are all in agreement that
1. TCAS is a last line of defence.
2. Pilots MUST ALWAYS follow RA advice
3. Controllers MUST give "AVOIDING ACTION" when necessary - and in the horizontal, not vertical plane.
airship
I think we came at opposite sides of the discussion here. I absolutely agree about following procedures and am happy to say that there are very robust ones in place. NATS, Swanwick in particular, has excellent annual Training in Unusual Circumstances and Emergencies (TRUCE).
However in the incident we are talking about, the controller was looking at a different radar display. Therefore, when he looked at the en-route display, it was pretty much already too late.
The picture we see is a 2D plan. In a moment of fear and instinctive action, the aircraft with right of way is not always blatantly obvious. When you are working hard and thinking quickly it is very easy to get your left and right mixed up - particularly when aircraft are moving north to south - I expect the majority of radar controllers here would admit to making the left/right mistake more than once in there careers so far.
The controller made the decision that seemed to be the right one in his mind at the time of the incident. We can not criticise him for that. We can however learn from the result - re: the top of my - points 2 and 3
cheers