NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
Before departing on the instrument flight rules cross-country flight, the private pilot obtained a weather briefing that forecast moderate icing conditions along the intended route. The pilot, a commercial pilot-rated passenger, and a second passenger then departed on the flight in the high-performance, single engine airplane, which was not certified for flight into known icing conditions. Both the pilot and pilot-rated passenger were heard communicating with air traffic controllers during the flight and it could not be determined who was flying the airplane at the time of the accident. About 1 hour, 45 minutes into the flight, the pilot requested a higher altitude and stated to a controller that the airplane was "picking up a little ice." The pilot was granted a higher altitude, which was above the clouds, thus, reducing the potential for icing. About 20 minutes later, the flight began its descent toward the destination airport. Radar contact was lost about 8 minutes later when the airplane was at an altitude of 3,600 ft mean sea level.
Based on an analysis of the weather conditions near the accident site at the time of the accident, the atmosphere was conducive to the formation of supercooled large droplet (SLD) icing. It is likely that, during the descent, the airplane encountered SLD icing, which rapidly accumulated on the airframe to the extent that the airplane could no longer sustain flight. The airplane then entered a steep, uncontrolled descent to ground contact. Due to the night conditions, it is possible that the pilots were not able to visually observe the amount of ice on the airframe or did not realize how quickly the ice was accreting. The airplane was equipped with a parachute system (CAPS) that could be deployed by the pilot in flight. The CAPS rocket motor was found expended; however, the parachute remained in its pack. The investigation could not determine whether the rocket was deployed before impact or as a result of impact forces. There were no observed airplane preimpact anomalies.