Originally Posted by FullWings
The (sadly last) communication from the Tu-154 to Zurich was: "'Ja', we have traffic at your... 2 o’clock now at 360". Where does the idea of an "unknown conflict" come from?
This communication was not from TU154M to ATC Zurich, but from the controller in Zurich to the TU154M crew.
This means that the TU154M crew was warned of traffic from 2 o'clock (by ATC) and from 10 o'clock (by TCAS and visually confirmed). This leads to the asumption (not only by PBL, but by the accident investigators at BFU), that the TU154M crew was occupied with the search for the traffic at 2 o'clock. The report says in chapter 2.6.3.1 under "Distribution of tasks" (on page 98 in the english version, on page 103 in the german version)
It is probable that he (PNF, TU154M) at least monitored the PF as the descent was initiated, but he then trained his attention on the visual search. He did not advise the PF that they were approaching teir cleared level of FL350. At this time the PNF's attention was concentrated on the visual search, and was probably centered in the wrong sector
(emphasis added).