[Sans-Culotte]

Never been in a helicopter, but it seems to me, visual. ..would he just as important as instruments. ?

Not in zero visibility, such as in a fog. Even with instruments, an aircraft could easily fly straight into a hill if he doesn't know it is there. They simply should not have flown in such weather.

[tflabo]

Some on the ground have reported the chopper’s engine sounded like sputtering just before the crash. Could the southward turn have somehow caused a loss of engine power?

[freeandfreezing]

Even with instruments, an aircraft could easily fly straight into a hill if he doesn't know it is there.

But every modern high end airplane and helicopter has onboard navigation systems with GPS based terrain displays. So the pilot, if competent, would always know their position relative to the terrain.

This seems like a case of a VFR pilot flying into IFR conditions. I am surprised anyone would fly what amounted to a commercial job around IFR conditions without being able to handle their aircraft in IFR conditions.