A few confirmed facts but still a few questions :
Fact : Flight rules/PLN was IFR. Req alt was 10.000
MSA was 6.9 until 25 NM. Radius HLM impactwas 28 NM .
Question 1 : what was the MSA at that point ?
fact :a/c was not under radar vector : reponsibility terrain clearly PIC.
Fact : discrepancy in the report on the ATC R/T phraseology used for the a/c to descend to 6000 ( below MSA)
Question2 :was the PLN vertical request made to descend below MSA followed by an ATC instruction ( XX descent to 6000 ) or was the request made in such a way that it was understood to be going down visually ? then the " 6000 copy" mentioned at the begining of the report could be understood.
It would be nice to see the R/T transcript.