The datas (FDR, CVR) will hopefully show in the future, what led to the disaster.
A_Van
Assume now that the ATC did not react to the crew at that point (e.g. was busy as it was a rush hour). What the crew had to do in this situation, i.e. a demo/experimental flight, Indonesian airspace with potential specifics vs Russia, Europe, US? Repeating the right-hand orbit once again waiting until the communication is re-established? Go on implementing the flight plan (U-turn and further descend)?
Lots of assumptions here. But given they apply, then staying in the orbit, or climbing in that orbit would have been an option. To continue with further descent when unaware of the terrain is suicide.
Keep going with the same course and altitude? If the latter, the crew would be moving towards the mountains as it likely happned.
No good plan, you might hit something or run out of fuel.
And if they were under VFR, this might not be a problem – e.g. they might be thinking «OK, let's wait for ATC and then make a turn after we pass the peak». But immideately after entering the mountains, they found themselves in a bad weather and the problems began.
If flying VFR, there is no sound reason to enter IMC with an air transport aircraft in mountaneous terrain. I would try both, stay out or get out of the mountains (climbing above MSA would be apropriate, would improve communication with ATC as well) and stay VFR by all means, and continue VFR on the planned routing. until communication with ATC is established.
Perhaps, they reported change to IFR, even tried to get up to the Grid MORA, but not pulling up steep enough.
There should be no need to pull up steep. When familiar with the performance of the aircraft planning ahead, staying clear of obstacles and maintaining VMC saves the day.
We should ask the question, what the task in the Bogor training area was. It´s kind of unusual to use a training area just to reverse course. That could have been done also under IFR in a level turn.
The descent in the wrong area finally brought them down to an altitude, where hitting ground was possible.