Accident Details
On November 14, 2023, at approximately 1008 mountain standard time, a Cessna 172G, registration N3971L, was substantially damaged when it impacted terrain in Slate Canyon near Provo, Utah. The pilot and front-seat pilot-rated passenger were fatally injured, while the rear-seat pilot-rated passenger sustained serious injuries. The flight was being conducted as a Title 14 Code of Federal Regulations Part 91 personal flight.
Flight Path and Witness Account
The passenger reported that the flight departed Spanish Fork Municipal Airport/Woodhouse Field (SPK) in Spanish Fork, Utah, at 1004, with an intended destination of Driggs/Reed Memorial Airport (DIJ) in Driggs, Idaho, for the purpose of building flight hours. He believed the pilot intended to remain outside Provo Municipal Airport (PVU) Class D airspace and Salt Lake City (SLC) Class B airspace. According to ADS-B data, the airplane flew north and east of PVU, west of Buckley Mountain, and into Slate Canyon, heading toward Corral Mountain, which peaks at about 10,100 ft msl and is located about 6 nm south of Highway 189.
The passenger stated that he could not hear any discussion between the pilot and front-seat passenger about the decision to fly eastward into the canyon. He noted windy conditions inside the canyon and recalled hearing the airplane's stall warning horn after the pilot attempted a right chandelle maneuver. The airplane was in a nose-high attitude before striking trees.
Wreckage and Examination
The wreckage was located about 6 miles northeast of SPK on a slope of Slate Canyon, approximately 2,000 ft below the summit at an elevation of about 7,900 ft msl. The first identified point of contact (FIPC) was a severed branch 70 ft up an aspen tree. The debris path, oriented on a magnetic heading of 280°, included subsequent tree strikes beginning about 80 ft forward of the FIPC. The main wreckage came to rest about 170 ft beyond the FIPC, oriented on a magnetic heading of 050° on a 35° slope. All major components were accounted for.
Postaccident examination of the airframe and engine revealed no preimpact malfunctions or anomalies. Flight control cable continuity was established. The elevator trim actuator measured 5° tab up, and the flaps were in the Up position. The fuel selector valve was in the Both position. Fuel lines were clear, and the carburetor showed no anomalies; fuel tested negative for water. The engine rotated freely, with thumb compression on all cylinders and normal valve lift. Borescope inspection of the cylinders showed normal piston face and valve signatures.
Performance Analysis
Performance calculations used an estimated takeoff gross weight of 2,079 lbs based on known weights. According to the Pilot's Operating Handbook, at a gross weight of 2,000 lbs and 5,000 ft msl at 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 ADS-B data point recorded an altitude of about 7,275 ft msl with a ground speed of 90 kts (approximately 69 IAS). The peak that the airplane needed to clear was about 10,100 ft msl and 2 nm from that point. Calculations indicated that to clear 10,150 ft msl at 610 ft/min would require about 5 minutes covering 6.5 nm; at 380 ft/min, about 8 minutes covering 10 nm; and to maintain 90 kts groundspeed would require a climb rate of about 2,300 ft/min for 1.5 minutes covering 2 nm.
The FAA Airplane Flying Handbook describes a chandelle as a maximum performance 180° climbing turn that ends in a nose-high attitude just above stall speed, noting that a common error is stalling during the maneuver.
Autopsies determined the cause of death for the pilot and front-seat passenger as blunt force injuries, with the manner of death accidental. Toxicological tests were negative for ethanol and substances of abuse.