Re: TCAS on Emer Descent
I raised this issue quite a few years ago whilst on my 767 command course. No real joy from the trainers so I went to have a chat with the engineers and after several faxes and emails sent bacwards and forwards around the world the "technical" answer was to select TA as other TARA equipped aircraft will issue their own (and if multiple - coordinated) RA(s) based on the assumption that you will maintain your existing vertical profile.
I still haven't seen any formal guidance from any manufacturer though.
Personally, by the time I think of it (in the sim) I am usually at least half way towards 10,000 feet/MSA and I think it would be an extremely sharp mind that would remember to select TA in "anger."