N3971L

On November 14, 2023, about 1008 mountain standard time, a Cessna 172G, N3971L, was substantially damaged when it was involved in an accident near Provo, Utah. The pilot and pilot-rated passenger in the front seat were fatally injured, and the other pilot-rated passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The passenger reported that they were flying from Spanish Fork Municipal Airport/Woodhouse Field (SPK), Spanish Fork, Utah, to Driggs/Reed Memorial Airport (DIJ), Driggs, Idaho, with the intent of building flight hours. He believed that the pilot’s intent was to maneuver to remain outside of the Provo Municipal Airport (PVU) Class D airspace, as well as the Salt Lake City (SLC) Class B airspace. According to ADS-B data, the airplane departed at 1004 and flew north and east of PVU and west of Buckley Mountain into Slate Canyon, toward the rising terrain leading to Corral Mountain, which peaked about 10,100 ft msl and was located about 6 nm south of Highway 189.

The passenger further reported that he was unable to hear any dialogue between the pilot and the front-seat passenger regarding the reason for the pilot's decision to fly eastward into the canyon. He also noted windy conditions in the canyon, that he heard the airplane’s stall warning horn after the pilot attempted a right chandelle, and that the plane was in a nose-high attitude before it hit trees.

Following a search and rescue mission after the Civil Air Patrol received an emergency locator broadcast, the airplane wreckage was located about 6 miles northeast of SPK on a slope of Slate Canyon, about 2,000 ft below the summit and at an elevation of about 7,900 ft msl. The airplane was oriented on a magnetic heading of 050° when it came to rest on a 35° slope. The first identified point of contact (FIPC) was a severed branch 70 ft up an aspen tree. The debris path was marked with subsequent tree strikes that began about 80 ft forward of the FIPC and oriented on a magnetic heading of 280°. The main wreckage marked the end of the debris path and was located about 170 ft beyond the FIPC. All major airplane components necessary for flight were accounted for at the accident site.

Postaccident examination of the airplane and engine did not reveal any preimpact malfunctions or anomalies that would have precluded normal operation. Flight control cable continuity was established from the cockpit controls to all surfaces. The elevator trim actuator was measured and found to be 5º tab up. The flaps were in the Up position. The fuel selector valve was examined and confirmed to be in the Both position. Compressed air was applied to the fuel lines and no obstructions were observed. The carburetor was removed and examined; no anomalies were noted. Fuel was found in the carburetor bowl and tested for water using water finding paste with a negative result.

Mechanical continuity was established throughout the rotating group, valvetrain, and accessory section as the crankshaft was manually rotated at the propeller by hand. Thumb compression was achieved at all four cylinders and the valves displayed normal lift when the crankshaft was rotated. Examination of the cylinders’ combustion chamber interior components using a lighted borescope revealed normal piston face and valve signatures, with no indications of catastrophic engine failure.

Performance calculations were completed using an empty of weight of 1,330 lbs, a pilot weight of 140 lbs, a front seat passenger weight of 182 lbs, a rear seat passenger weight of 185 lbs, and a fuel weight of 252 lbs. Based off these values, the airplane’s calculated gross weight at takeoff was 2,079 lbs. According to the POH, at a gross weight of 2,000 lbs, 5,000 ft msl, and 41°F, the maximum rate of climb is 610 ft/min at 66 kts indicated airspeed (IAS). At 10,000 ft msl and 23°F, the maximum climb rate is 380 ft/min at 64 kts (IAS). The last recorded altitude on ADS-B data was around 7,275 ft msl with a ground speed of 90 kts, which was calculated to be approximately 69 IAS. The peak that the airplane had to clear was approximately 10,100 ft msl and 2 nm from the last recorded data point.

Figure 1. View of ADS-B overlay on Google Maps depicting aircraft's flight track into mountainous terrain.

For the airplane to clear 10,150 ft msl at a maximum climb rate of 610 ft/min, the airplane would need about 5 minutes, covering about 6.5 nm in that time. At a maximum climb rate of 380 ft/min, the airplane would need about 8 minutes, covering about 10 nm. In order to maintain 90-kts groundspeed, the airplane would need a climb rate of about 2,300 ft/min which would clear 10,150 ft msl in about 1.5 minutes, covering about 2 nm.

The FAA Airplane Flying Handbook, Chapter 10: Performance Maneuvers, stated that a chandelle is “a maximum performance, 180° climbing turn that begins from approximately straight-and-level flight and concludes with the airplane in a wings-level, nose-high attitude just above stall speed.” It added that a common error when performing chandelles is “stalling at any point during the maneuver.”

The fatally injured pilot and front seat pilot-rated passenger's autopsies were performed by a Forensic Pathologist of the Utah County Sheriff's Office, Taylorsville, Utah. According to the autopsy reports, the cause of death for both was blunt force injuries, and their manner of death was accidental.

The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological tests on specimens recovered from the pilot and pilot-rated passenger. Their specimens tested negative for ethanol and any substances of abuse.