History of Flight
On July 14, 2022, at 1231 mountain daylight time, a Cessna P210N (registration N731BJ) was destroyed in an accident near Buffalo, Wyoming. The pilot and passenger were fatally injured. The flight was operated as a personal flight under 14 CFR Part 91. Recorded ADS-B data indicated that the airplane departed from Powell Municipal Airport, Powell, Wyoming, and proceeded southeasterly, climbing to 17,450 ft msl. It maintained that altitude for about 9 minutes 17 seconds, then descended to 15,400 ft msl within 12 seconds. About 2 seconds later, it climbed to 15,575 ft msl, then descended to 14,500 ft msl over the last 4 seconds of data. The last data point was located 0.46 miles northwest of the accident site at an altitude of 5,680 ft agl. According to local law enforcement, fire crews responding to reports of a wildland fire located the wreckage in rugged mountainous terrain about 14 miles west-northwest of Johnson County Airport, Buffalo, Wyoming. A witness who was riding a horse about 4 miles south of the accident site reported hearing the airplane sound normal until just before impact, then a distinct over-rev of the engine followed by the impact.
Meteorological Information
The accident site was situated between a high-pressure and low-pressure system with a weak pressure gradient. The nearest official weather station was at Johnson County Airport (BYG), Buffalo, Wyoming, located about 12 miles east of the accident site at an elevation of 4,970 ft. At 1245, the National Weather Service Aviation Weather Center display depicted general VFR conditions over Wyoming with clear skies below 12,000 ft, unrestricted visibility, variable winds, and temperatures ranging from 82°F to 90°F. GOES-16 visible imagery at 1226 showed clouds over the general route of the last 5 minutes of the flight. Infrared imagery at 1231 depicted cumulus clouds over the eastern slopes of the Big Horn Mountains and in the vicinity of the accident site, with radiative cloud top temperatures ranging to 253 Kelvin (-20°C), corresponding to cloud tops near 26,000 ft based on the HRRR sounding. The atmosphere was characterized as unstable, with a Lifted Index of -4.9, CAPE of 1,005 J/kg, and DCAPE of 841 J/kg, supporting thunderstorm development as indicated by the HRRR sounding from 1300 MDT. The sounding-derived maximum vertical velocities in potential convective updrafts were 45 m/s (90 knots). The sounding also supported strong thermals to about 18,000 ft with estimated maximum lift of 757 ft per minute. The sounding indicated potential for scattered altocumulus clouds at 9,500 ft agl (16,625 ft msl) near the airplane's cruising level. No record that the pilot received a formal weather briefing was found.
Wreckage and Impact Information
Local law enforcement reported that the wreckage impacted a hillside within mountainous terrain. Due to limited site accessibility, the National Transportation Safety Board did not travel to the accident site. Examination of the recovered wreckage revealed extensive fragmentation and fire damage. The outboard portion of the left wing from wing station (WS) 112 to the wingtip end rib was recovered; the inboard portion of the left wing spar was intact from WS 25 to WS 41, but wing structure between WS 41 and WS 112 was not identified. Three of four left wing fittings remained attached; one fitting separated, and its fracture surface was consistent with overload. The right wing spar exhibited a 90° bend between WS 25 and WS 94, continuing outboard to WS 143; wing structure beyond WS 143 was not identified. The right aileron bell crank had separated from the wing structure. The fuselage was severely fragmented and mostly consumed by fire. Portions of the left elevator including the left counterweight, a 12-inch outboard portion of the right elevator with its counterweight, and portions of the right horizontal stabilizer were recovered. About 37 inches of vertical stabilizer rear spar and 31 inches of rudder remained attached, exhibiting significant thermal damage. The engine was impact and thermally damaged; rotational signatures were observed throughout the compressor, with multiple stages of blades bent opposite the direction of rotation. Continuity was established from the compressor aft to the gas producer turbine, which rotated freely by hand. No evidence of thermal distress was observed in the turbine. Engine controls were not located within the recovered wreckage.
Medical and Pathological Information
An autopsy performed for the Johnson County Coroner determined the cause of death as "multiple blunt force injuries from airplane crash (instantly)." None of the brain, heart, or lungs were available for examination. Toxicology testing conducted by the Federal Aviation Administration Forensic Sciences Laboratory detected ethanol in the pilot's muscle tissue at 0.027 gm/hg but not in his liver tissue; n-propanol was also detected in muscle but not in liver. Tissue samples exhibited putrefaction. The antianxiety medication diazepam was detected in liver tissue at 12 ng/g but not in muscle; its metabolite temazepam was present in liver at 503 ng/g and muscle at 121 ng/g; another metabolite, oxazepam, was detected in liver. The blood pressure medications chlorthalidone and atenolol were found in liver and muscle, and are generally considered non-impairing. No blood specimens were available for toxicology testing.