SEA84MA016

The plt took off from the simplot ranch airstrip which was located beside the middle fork of the salmon river, aprx 27 mi northwest of Challis, ID. He departed downriver toward the northeast, but the destination was a usfs strip about 7 mi upriver to the southwest. A course reversal normally would have been made about 6 mi downriver. However, a turn- around was attempted over a relatively shallow (bench) area on the west side of the river, about 1-1/4 mi from the departure strip; where, according to the operator, it could have been made under ideal conditions. The acft crashed in the bench area while on a westerly heading. It came to rest in an upright attitude with little evidence of forward velocity, but with severe vertical collapse. No evidence of a preimpact mechanical malfunction or failure was found.