Ah, you meant which specific RA. While I don’t know, that’s become a more deterministic answer in the case of an airplane not following the instructions (or not

Ah, you meant which specific RA. While I don’t know, that’s become a more deterministic answer in the case of an airplane not following the instructions (or not having TCAS) because of Überlingen and the introduction of TCAS reversals… in other words exactly as you said, it’ll 1. change if the other aircraft reacts in the wrong way and 2. there’s a much greater clarity and emphasis in following the RAs in all cases except for GPWS in great part because of Überlingen. Edit: never mind the last bit, RAs actually get completely suppressed if GPWS does its thing, TAs still go through.