Very sad news , the Grid Mora on that zone is 15.000 fts, as i saw on the map they didnt used the normal route , that is to fly over the valley until t reach the minimum sector altitude. why was that? is a big question that can be awnsered by the black box.
http://www.centrocas.com/YV1449RH1.asp
captain had 9 year operating that route
copilot had at least 4 years operating that route , flying the ATR and Beech 1900
lets wait for the INAC bouletin
Que dios los tenga en la gloria , paz a sus restos.