janeczku
According to the report, the FMS doesnt provide vertical control signal. As the autopilot was engaged in pitch-channel until the last seconds, the crew must have absolutely entered the pitch manually into the ABSU sometime at the start of the final descent. The report argues that the crew switched to autopilot pitch channel by using the "DESCENT-CLIMB" wheel at 9km from RWT.
This
graphics (sorry in Polish) best explains the whole situation and it is said to be based on all the Flight Data Recorder data.
It shows the ATC regularly (every 13 seconds) giving his readouts and shows how it was possible that all those ATC (on-course, op-path) calls were correct if 13 second interval is all what the equipment allowed him to do or what he could do. To me, this proves that the pilots were increasing the rate of descend as a result of passing the valley (which made them think they were too high). Then, then the up-slope started, all of the sudden their perceived (RA-based) descend rate became about 4 times higher than a moment earlier.
It is hard to nit-pick any more at what was done. The only thing that can be argued is WHY.