ERA12FA051 · Cessna 150F

According to a flight instructor, the pilot’s intent was to practice for an upcoming flight review. There were no witnesses to the accident; however, a witness at the airport observed the pilot park his car near the hangar that housed the airplane, untie the airplane, and pull it out of the hangar. Then, as the witness was leaving the airport, he saw the pilot get into the airplane. The witness also noted that the sun had gone down, but it was not quite dark when he left. Radar data for the timeframe just after the witness observed the pilot indicated a target transmitting a 1200 transponder code that is consistent with the airplane’s location. Just after sunset, the airplane took off and, after a brief flight to the northwest of the airport, entered the airport traffic area and completed a landing. After 5 minutes, the airplane was again airborne, and, according to radar data, completed another landing or a low approach. There was no further radar contact.

The pilot was reported missing 11 days after the accident and was found 3 days after that about 30 feet away from the airplane wreckage. The wreckage came to rest wedged between several trees about half way along, and to the right of, the runway about 60 feet outside the northwest airport perimeter fence. Initial tree cuts were consistent with an approximate 45-degree right-wing-down turn and 45-degree angle of descent, which is consistent with the pilot’s loss of control in flight. An examination of the wreckage revealed no mechanical malfunctions or failures that would have precluded normal operation.

The pilot’s location at the accident site indicated that he was able to unhook his seatbelt and extricate himself from the airplane. Autopsy results for the pilot indicated that the cause of death was most likely the “toxic effects of ethylene glycol,” a substance most frequently encountered in antifreeze fluid. Toxicological testing did not reveal the presence of ethylene glycol, but the autopsy found associated crystals in the kidney, indicating that the pilot survived long enough for the substance to clear his system. Initial symptoms of ethylene glycol poisoning mimic acute ethanol intoxication, with slurred speech and ataxia. Depression of the central nervous system can result in coma. Kidney failure is a late stage symptom.

According to the pilot's logbooks, his most recent flight review was about 9 years before the accident, and his most recent recorded flight was about 5 months before the accident. It was unknown if the pilot had recently flown but not logged the flight time. Although the pilot’s lack of recently logged flight time could indicate a loss of airplane control related to a lack of currency, it is far more likely that the debilitating effects of ethylene glycol posioning rendered him unable to control the airplane while airborne. How or why the pilot may have ingested ethylene glycol is beyond the scope of this investigation.

Verbatim NTSB analysis and probable cause from the NTSB dataset