CEN24FA089 · Cessna 310R

Before departing on an instrument-flight-rules (IFR) cross-country flight, the pilot obtained a standard weather briefing of the forecast and observed weather conditions along the flight route, which included AIRMETs for moderate icing between the departure and destination airports during the time of the filed IFR flight plan. The airplane was likely in instrument meteorological conditions during the descent between 6,000 ft and 3,000 ft msl in moderate or greater icing with supercooled large droplets. Below 3,000 ft, the accident flight was likely in visual meteorological conditions and below freezing temperatures. During the descent, ATC attempted to communicate with the pilot for about 7 minutes with no response from the pilot. The descent profile was controlled on a relatively straight heading and the witness marks on the ground, damage to the airplane, and distribution of the wreckage were consistent with controlled flight into terrain. The airplane impacted a field in a relatively level attitude. The airplane may have accumulated some ice while descending through the cloud layer. However, the ½ mile long wreckage path from initial impact with the ground to where the main wreckage came to rest is not consistent with loss of control due to ice accumulation. The witness seeing the airplane flying parallel to the ground in a wings level attitude also suggests that the airplane did not depart controlled flight. Due to the fragmentation and thermal damage to the airplane, functional tests of the system were not possible; however, there was no evidence to suggest a preimpact anomaly with the flight controls or engines which would have precluded normal operations. The pilot’s moderate coronary artery disease conveyed some increased risk of a sudden impairing or incapacitating cardiovascular event, such as chest pain, arrhythmia, or heart attack. The autopsy did not provide specific evidence that such an event occurred; however, such an event does not leave reliable autopsy evidence if the event occurs shortly before death. Ethanol levels measured by two laboratories were elevated to a relatively similar degree in vitreous fluid and urine, indicating a possibility that the pilot may have consumed alcohol and may have been impaired by ethanol effects at the time of the accident or while engaged in earlier activities related to the safety of flight. However, cautious interpretation of the alcohol results is prudent, given the extent of the pilot’s injuries, the fact that only two specimen types were tested for ethanol, and the detection of other volatiles in both of those specimen types. It is possible that some or all of the detected ethanol may have been from postmortem sources rather than alcohol consumption. Although toxicological results also indicated that the pilot had used the medication cetirizine, no determination could be made from the medical evidence indicating whether the pilot might have been experiencing some associated sedation at the time of the accident. Based on the available evidence, it is possible that the pilot became incapacitated during the descent. The reason for the incapacitation could not be determined.

Verbatim NTSB analysis and probable cause from the NTSB dataset