At approximately 1015 central time, a Cessna 208B crashed while landing at Ducote Airpark. The check airman and the pilot who was receiving a Part 135 proficiency check suffered serious injuries. The airplane took off from San Angelo Regional Airport, executed a few instrument approaches and then canceled IFR to head to Ducote. Witnesses said they heard an engine surging and saw the airplane approaching from the south. They stated that the airplane was approximately 100-200 feet agl with the wings rocking, then the airplane struck power lines and crashed. One witness said he smelled jet fuel at the accident site but did not see any fuel there. Two of the witnesses reported between a quarter-inch and one inch of ice on the various protected and unprotected surfaces of the aircraft.