PBL, phrases like 'use of TCAS has almost caused two collisions' and 'he potential outcome at Albany was ameliorated through intervention of a controller' suggest to me that you are reading something into facts (based largely, I presume, on the occurrence investigation reports) - I've always called this analysis and, in this case, it's simplistic. FWIW, I don't equate simplistic with bad, I just like to be aware of the assumptions and aproximations that have been made. Just to be absolutely clear, a statement of fact would be that two aircraft that were within a specific distance of each other generated a TA or RA. The problem with any quantitative analysis designed to assess TCAS effectiveness, or for that matter, the probability of occurrence of some identified failure mode, is that there is no complete data set and thus some assumptions must inevitably made.
The point being that judging whether TCAS is a good idea or not is not a data-based decision, as Frangible was suggesting it was.
If it is not data-based to the extent that the data can be relied upon, and I accept that we could have a lengthy debate about pass/fail criteria etc., what would you base the decision on?
Ah, that word "simplistic" comes to mind, along with "straw man".
Sadly, I think it must be my simplicity but I don't understand your point. All I was saying was that TCAS exists now, just as today's traffic levels exist, and whatever else you might want to cite in the environment in which we operate, and we have to use it as effectively as possible. In order to do so we have to analyse everything we know about it in the best way that we know how. I wasn't suggesting any gung-hoing!
But if I might end with a slightly contentious thought, one of the 'problems' with TCAS was the unilateral way that it was introduced without consideration of the system totality and, if I recall correctly, in a knee-jerk reaction to a mid-air collision. And we are still trying to fix the problems that this created. As I say, we should learn from the past, but it seems to me that, in some respects at least, contemporarily we are seeing a similar course of events over another safety net system, that designed to address runway incursions and the associated risks.