History of Flight
On September 22, 2017, about 1635 mountain standard time, a Cessna 172L, N7070Q, collided with mountainous terrain near Perkinsville, Arizona. The private pilot and passenger sustained fatal injuries, and the airplane was destroyed by postimpact fire. The airplane was registered to Peach Flyers LLC and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Ernest A. Love Field Airport (PRC), Prescott, Arizona, at 1621 with an unknown destination.
The pilot had told family members he planned to fly with his friend, the passenger, and remain in the traffic pattern at PRC performing touch-and-go landings.
Federal Aviation Administration radar data from Seligman, Arizona, and audio recordings from the PRC tower showed that after contacting ground control, the pilot switched to tower frequency and requested a departure to the northeast. Clearance was granted, and after takeoff from runway 21R, a radar target with transponder code 1200 entered the right downwind and departed northeast. Over 2.5 minutes, the target climbed to 7,175 ft mean sea level (msl), about 2,100 ft above field elevation, then leveled off 2.75 miles northeast of the airport.
For the next 8 minutes, the target gradually descended while maintaining northeast track at about 110 knots ground speed. The last target at 1632:47 showed 95 knots just west of the Verde River Canyon entrance at 4,550 ft msl (750 ft above the river). No radar data indicated the airplane emerged from the canyon or reached Cottonwood.
The following morning, concerned family alerted the sheriff's department. At 1108, the FAA issued an Alert Notice. A helicopter search using radar and cell phone data led to discovery of the wreckage at about 1300 within the Verde River Canyon, 1.8 miles east-southeast of the last radar target and 19 miles northeast of PRC.
Aircraft Information
The 1972-manufactured airplane was originally equipped with a 150-horsepower Lycoming O-320 engine, upgraded to a 180-horsepower Lycoming O-360 in 2005 per supplemental type certificate SA4428SW. This increased maximum gross weight from 2,300 to 2,500 lbs. Fuel capacity was 42 gallons, consumption varied from 6.1 to 10.3 gallons per hour. Weight and balance information was not located; the owner's manual indicated a typical basic empty weight of 1,364 lbs.
The airplane was owned by a limited liability corporation of which the pilot was a member for about one year. The pilot was the predominant operator. The airplane was hangared. The last fueling records showed 25 gallons of 100 low-lead aviation gasoline added at Cottonwood Airport (P52) on September 8, 2017. The pilot who fueled it reported no discrepancies. The accident pilot flew the airplane only once after fueling, a 1.5-hour instrument training flight on September 20.
Meteorological Information
Surface observations at PRC at 1653 indicated wind from 200° at 15 knots gusting to 22 knots, 10 miles visibility, clear skies below 12,000 ft, temperature 19°C, dew point -9°C, altimeter 29.86 inches of mercury. Gusty winds from 180° to 200° at 12-17 knots with gusts to 27 knots existed throughout the afternoon. Similar conditions at Sedona Airport at 1635 showed wind from 210° at 16 knots gusting to 24 knots.
A High-Resolution Rapid Refresh model for the accident location at 1700 depicted surface temperature 23.2°C, dew point -3.9°C, relative humidity 16%, density altitude 6,255 ft, and surface wind from 210° at 11 knots, supporting strong thermals to 9,000 ft. Wind profile indicated south-southwesterly winds 10-20 knots through 10,000 ft. At the airplane's last radar altitude of 4,550 ft, calculated conditions included wind from 210° at 14 knots, temperature 21°C, density altitude near 6,343 ft.
The National Weather Service Flagstaff sounding showed a temperature inversion at 6,240 ft agl, strong thermals, and surface wind from 190° at 10 knots gusting to 26 knots, with increasing speeds aloft. It indicated moderate potential for low-level wind shear and moderate or greater turbulence below 1,000 ft agl. No significant pilot reports of turbulence below 8,000 ft were available. A flight instructor in the vicinity at the time reported south-southwesterly winds near 25 knots, light turbulence through 9,000 ft, and described it as an ordinary windy day.
A Weather Research and Forecasting model simulation from 1600-1700 showed moderate turbulence over the area, wind speeds of 18-20 knots at the accident site around 1630, and vertical velocities ranging from 300 fpm down to 500 fpm up.
Wreckage and Impact Information
The airplane came to rest at 4,290 ft msl on 45° sloping walls at a river turn on the north cut bank of the canyon, about 200 ft below the canyon rim and 500 ft above the river. The area was strewn with sandstone slabs, rocks, and boulders up to 8 ft in size.
The cabin and wings came to rest inverted on a heading of about 030° true. The aft fuselage and empennage rotated 90° to the right; the outboard right wing folded underneath itself about midspan. Fire consumed the main cabin and most of the right wing inboard of the aileron. The empennage and left wing outboard of the pitot tube remained largely undamaged. The engine and firewall wedged between boulders on the upsloping side.
The wreckage was tightly contained, with no damage to surrounding terrain; all control surfaces were accounted for. Examination of the engine and airframe was performed post-recovery. The fuselage from the firewall to the baggage door frame was fire-consumed; remnants included the main landing gear. The left door detached, right door consumed. Forward seats were consumed except steel components; lap buckles were latched, belts consumed.
The empennage remained attached; left side of aft fuselage undamaged, right side thermally damaged. Elevator remained attached; trim tab control rod extended 1.25 inches, consistent with 5° tab-down (elevator up). Left wing intact except thermal damage to inboard leading edge; flap and aileron attached. Stall warning horn consumed. Right wing inboard section consumed; flap actuator jack screw showed about 1/8 inch extension, consistent with fully-retracted flaps.
Engine remained attached to mount and crushed firewall, sustaining thermal damage to right magneto, spark plug harness, oil sump, alternator, and accessory case. Carburetor sustained extensive thermal damage. Fuel inlet line fitting in place, screen unobstructed. Borescope inspection of combustion chambers showed no foreign object ingestion or valve damage; surfaces coated in grey deposits. Crankcase had no breaches; drive train continuity established. Propeller remained attached; one blade tip melted away about 24 inches from root, remaining section had 1-inch-deep leading-edge gouges midspan. Second blade bent about 15° aft midspan, tip separated about 28 inches from root.
Medical and Pathological Information
Autopsy by the Yavapai County Office of the Medical Examiner determined cause of death for both pilot and passenger as thermal injury with smoke and soot inhalation, along with multiple blunt force trauma. Toxicology testing by the FAA Forensic Sciences Laboratory was negative for carbon monoxide, all screened drugs, and ingested alcohol.
Tests and Research
The radius of the river bend at the canyon base was approximately 300 ft; at the wreckage elevation, about 1,050 ft; at the canyon rim, 1,400 ft. Turning performance data from Aerodynamics for Naval Aviators indicated that a true airspeed of 79 mph required a 61° bank for a 300-ft radius turn and a 27° bank for a 1,050-ft radius turn. The supplemental flight manual for the upgraded engine showed that at 2,500 lbs gross weight, flaps up, stall speed was 59 mph (calibrated). At bank angles of 20°, 40°, and 60°, stall speed increased to 62, 68, and 84 mph, respectively. The owner's manual indicated a maximum rate of climb at 2,000 lbs gross weight, zero flaps, full throttle, and 79 mph indicated airspeed of about 570 ft per minute at 5,000 ft and 20°C.