How do we know they did not have a rock solid plan to avoid obstacles (including Blackrock that was at least 82 feet ABOVE their chosen height)?
What if they did.....but something intervened to undermine their Plan?
We do not know what their Plan was as there is insufficient data in the public domain to make that determination.
Plainly, something happened as they were killed when the aircraft impacted terrain despite there being some warning....as noted by the CVR Transcript.
The key to the puzzle will be in ascertaining why the Crew chose such a height despite the known obstacle provided by Blackrock....and then when warned of the proximity of Blackrock by the FLIR Operator....did not take IMMEDIATE Action to avoid the terrain in front of them.
I would think a review of the Unit SOP's, Crew Briefs for this incident, and a review of other Crew Briefs/Practices by this Crew in particular and the Operation Crews in general will shed a lot of light on how business is done during similar weather/night approaches.
Again, legacy practices , SOP's, and incorporation of new technology issues should be carefully considered.