ATC rule for air conflic
I think the TCAS's RA is based on the aircraft position / flight direction.
For the aircraft flying West to East or v.v, the TCAS will give Ascending command. And for the aircraft flying North to South or v.v, the TCAS will give Descending command.
To avoid a conflict between the TCAS'RA and the ATC command, I think the ATC-man should has a Rule , which should be the same as the TCAS's rule.
It is, when a conflict seen on the Radar display, the ATC man should order the East-West flying aircraft to climb, the North-South flying aircraft to descend.
It would be good also to tell the pilots, as a Pilot's rule, that for pilot flying East-West should fly ascending, and for the pilot flying North-South to fly descending, in case of a flight conflick.
By applying the same Rule , I hope there will be no bad news again in the future.