Evil7...... The landing sites on the edges of the river are very rough with big boulders . The only way to land most helis would be to just put one wheel or skid onto a rock and pax climb out . In blustery weather and with ice on the rocks this is fraught with danger for all concerned !! The Mi8 hs huge balloon type tyres and massive clearance so can usually fully land . When they tried a Eurocopter it rolled over and killed the pax who were outside ....