Hug...agree totally.You have answered your own question earlier when you said the holes where lining up and the chain could have been broken at any stage.As to giving descent..I agree...he could also have called his mate back into the ops room(we are encouraged to do so).Management could also have had some sort of "quality assurance" in place whereby it could be shown that to remove a principal piece of equipment e.g. direct dial telephones the standby equipment would be serviceable and routing the calls correctly. As to TCAS ...I may be dim ..but is there a stage in the process where(as it appears on the documentary)the second aircraft is not responding in the manner agreed by the two transponders that one says (electronically) ****** this lets look for another solution and changes its' mind...for example BOTH aircraft now descending.TCAS thinks lets try CLIMBING one?
Bring back fam flights!!