Coonor is a weird area the hills overlap each other with tight spot so its susceptible to ground weather effect, the fog moves like a blanket of waves,you might be experiencing sunny day within a minute a fog pocket approach the areas n reduce the visibility to few meters, meanwhile other side of the hill experiencing nice sun shine.
If i have to make an educated guess(if there is no foul ) pilot started to lower his altitude while he was experiencing nice weather suddenly met with rolling fog blanket as i mentioned earlier
n struggled to find direction n lost his way.
Found himself gwr blaring n tried to pull up with full rev(hence the witnesses huge sound comment) n failed to gain altitude.
Im not saying sabotage is outta question but i posted this scenario if it were an accident.