I am not against the TCAS system, it is just that if it is OK to install it now, why not 20 years ago; the basic system has not changed that much.
Let's see if the SI contains this information.
No need to wait for the SI on that one. This was merely another symptom of the illness diagnosed by Bernard Gray before he became CDM, namely the institutionalised gold-plating of requirements, under-estimation of technical risk as a means of securing funding when pursuing novel programmes, and a systematic refusal to contemplate the off-the-shelf 80% solution. TCAS was only adopted when there was literally no other option - and judging by the time taken to get it into service, I wouldn't be surprised to see evidence of a rear-guard action by the gold-platers....