Ooooh, I suspect there are a few issues here. Firstly, I understand that a ROC/ROD in excess of about 8000ft/min will 'confuse' TCAS. Secondly, there must be a question about the ability of the airborne systems in the conflicting aircraft(altimeter/transponder etc) to keep-up with a high ROC/ROD. If these are transmitting false or out-of-date data, then the TCAS will be presenting a resolution based on old information. Furthermore, under such circumstances, the Mode C data may well drop out thus rendering TCAS useless (in the RA sense).