CESSNA 172 — Hooker , OK

What happened

The non-instrument-rated pilot completed a cross-country flight on the morning of the accident in visual meteorological conditions. By the time he departed on what appeared to be a return flight to the airport of origin, weather conditions had deteriorated, and the forecast at the destination airport included 5 statute miles visibility, mist, and a broken ceiling at 800 ft above ground level (agl). Flight track information indicated that, about 2 hours after departure and about one hour after sunset, the airplane entered a decreasing-radius, 720° descending left turn from an altitude of about 4,500 ft mean sea level (msl). The airplane briefly resumed level flight at an altitude of about 3,300 ft msl before track data was lost in the vicinity of the accident site, about 16 nautical miles from the destination airport. Postaccident examination of the airplane did not reveal any preimpact anomalies.

Review of weather conditions revealed that, about the time of the accident, the destination airport and another nearby airport both reported an overcast ceiling of 500 ft agl. Review of a model atmospheric sounding for the accident site indicated an overcast cloud layer from about 3,700 ft through 4,900 ft, the presence of icing below about 5,000 ft, and the potential for turbulence between about 10,000 ft and 4,400 ft, including extreme turbulence around 5,000 ft. There was no record of the pilot obtaining a weather briefing from an access-controlled source before departing on the accident flight.

Toxicological testing of the pilot detected the synthetic opioid tramadol and its metabolites. Tramadol use may impair psychomotor functioning likely to be important in the performance of complex, divided-attention tasks such as flying. Opioid use can influence judgement and behavior and has been reported to increase the risk of spatial disorientation in pilots. In addition, opioid users have been shown to have decision-making deficits when compared to non-users.

Given that the pilot did not hold an instrument rating, and his most recent recorded simulated instrument and night flight experience was about 10 years before the accident, the pilot was susceptible to the development of spatial disorientation while operating in night instrument meteorological conditions. The airplane’s decreasing-radius, descending turns depicted on ADS-B data just before the accident are consistent with the known effects of spatial disorientation. The extent to which his use of tramadol contributed to the loss of control or his decision to depart on or continue the flight into deteriorating weather conditions could not be determined based on the available information.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.