I am not going to speculate on the reasons for this terrible crash as I and none of us know all of the facts.
With regard to TCAS, there are many many traffic conflicts that occur that would otherwise have resulted in a possible collision. Instead of complete devastation all that happens in the majority of cases is a bit of extra paperwork at the end of a flight. As long as there are at least 2 aircraft in the same region of airspace there will always be a very small risk of collision, particularly when only 1 has TCAS, but TCAS is something I would not leave base without particularly as the skies become more and more congested. Should TCAS be partly to blame for this accident it's benefits far outweigh it's flaws.
ES
