DEN87FA024

The plt agreed to ferry the acft for another plt who was not IFR rated & who had been forced to land at kadoka on the previous evening due to low fuel & apchg darkness. IMC prevailed thru-out the area. The commercial/ifr rated plt did not obtain a wx briefing or file a flt plan. He took off & contacted ellsworth afb apch control at 1535 MST. Later, he rprtd level at 6000' MSL & said the top of the overcast was at 5000'. When told that both rapid city & ellsworth afb were below apch mins, he elected to divert to spearfish, SD. Radio & radar contact were lost at 1606. On the following afternoon at 1415, the wreckage was fnd where the acft had collided with trees on a 4800' high mtn at about the 4650' level. There was evidence the acft impacted in a wings level, slightly nose low attitude at cruise airspeed. The cockpitwas destroyed by impact & gnd fire. Medical & toxicological checks revealed no evidence of plt incapacitation. The elev trim was fnd set in a slightly nose-down psn.