Accident Details
On October 16, 2017, at about 1430 Alaska daylight time, a Cessna 210-5 airplane, registration N8347Z, was destroyed when it impacted the Yukon River about 10 miles southwest of Russian Mission, Alaska. The private pilot, who was the sole occupant, sustained fatal injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 and originated from Kako Airport, Kako, Alaska, at about 1415, with a destination of Bethel Airport (PABE), Bethel, Alaska. No flight plan had been filed for the visual flight rules (VFR) flight, and no record of the pilot receiving a preflight weather briefing could be found.
Instrument meteorological conditions prevailed at the accident site. According to a pilot who departed about 10 minutes ahead of the accident airplane on the same route, there were widespread areas of low-level fog (between 400 and 600 ft above ground level) along the route. This pilot conversed with the accident pilot after departure about the fog layers. No further radio communications occurred. The interviewed pilot tried to contact the accident pilot about 15 minutes later but received no response. After landing at Bethel and loading passengers, he searched for the accident airplane on a return flight but could not locate it. He notified the FAA Flight Service Station, and an alert notice (ALNOT) was issued at 1748. The accident airplane was found submerged in the Yukon River on October 17.
Aircraft and Pilot Information
The airplane, manufactured in 1963, was equipped with a Continental Motors IO-470 series engine. Its last annual inspection was completed on September 8, 2017, at which time the airframe had accumulated 5,533.7 total hours and the tachometer read 1,649.2 hours. The pilot, aged 31, held a private pilot certificate with an airplane single-engine land rating but did not have an instrument rating. His most recent third-class medical certificate was issued on February 1, 2014, without waivers or limitations. At the time of his medical application, he reported 35 hours of total flight experience; a relative estimated he had accumulated about 160 hours.
Weather Conditions
The National Transportation Safety Board (NTSB) performed a detailed weather study. The Russian Mission Airport, about 9 nautical miles north-northeast of the accident site, reported at 1413: wind 140° at 3 knots, visibility 10 statute miles, scattered clouds at 300 ft, scattering at 2,600 ft, broken ceiling at 3,600 ft, temperature 37°F, dew point 36°F, altimeter 29.68 inHg. At 1446, a METAR reported wind 170° at 4 knots, visibility 10 miles with light rain, scattered clouds at 1,000 ft, broken ceiling at 2,300 ft, overcast at 3,400 ft, temperature 37°F, dew point 34°F, altimeter 29.68 inHg; rain began at the airport at 1432. Marshall Don Hunter Sr. Airport, 21 nm northwest, reported at 1356: wind 250° at 4 knots, visibility 10 miles, broken ceiling at 2,700 ft, overcast at 3,500 ft, temperature 37°F, dew point 35°F, altimeter 29.67 inHg.
One pilot report (PIREP) was available within 200 nm and below 18,000 ft: over Aniak at 1512, a Cessna 208 pilot reported an overcast ceiling at 700 ft with cloud tops at 4,000 ft. The area forecast issued at 1206 valid at accident time forecast an AIRMET for instrument conditions, broken to overcast ceiling at 300 ft with cloud tops at 10,000 ft and visibilities below 1 mile in mist, with improving conditions forecast. The closest WSR-88D radar near PABE detected reflectivity and rain showers above the accident site at 1422 and 1432, moving from southwest to northeast. FAA aviation weather cameras in Russian Mission showed rain showers, low ceiling, and visibility conditions, with a low bank of clouds toward the Yukon River and the intended flight route.
Wreckage and Impact
The airplane was located submerged about 15 feet in the Yukon River, about 10 miles southwest of Russian Mission. The main wreckage was recovered and moved ashore; a portion of the forward fuselage, engine, and wings were located but not recovered. The horizontal and vertical stabilizers remained attached to the empennage. The vertical stabilizer and left horizontal stabilizer had minimal impact damage. About 3 feet of the outboard portion of the right horizontal stabilizer and elevator was displaced upward about 45° with no leading-edge nicks or gouges. The aft fuselage separated from the forward fuselage at the upper production joint near the forward end of the rear windows. Rivets on the left side were pulled through, consistent with the left wing rotating forward; rivets on the right side were popped out, consistent with the right wing rotating aft. The front left seat was found 5 miles downstream without compression damage; the front right seat, found 10 miles downstream, showed compression damage on the bottom right side, more on the forward right side.
Additional Information
An FAA safety brochure on spatial disorientation notes that when the natural horizon is obscured, attitude can be maintained by visual reference to the surface or by artificial means. Lack of horizon or surface reference is common in low visibility conditions, on over-water flights, or at night.
Medical and Pathological Information
An autopsy conducted by the State of Alaska Medical Examiner's Office determined the cause of death as multiple blunt force injuries. Toxicological testing by the FAA's Bioaeronautical Sciences Research Laboratory was negative for drugs, ethanol, and carbon monoxide.
Tests and Research
The airplane was equipped with a J.P. Instruments Engine Data Monitor (EDM) model 730. Data recorded from 1418:42 to 1431:06 in 6-second intervals showed engine parameters consistent with run-up at 1420:30 and 1421:30, takeoff roll at 1421:40, and nominal parameters for about 9.5 minutes until the end of recording. The final data showed cylinder head temperatures 290°–365°F, exhaust gas temperatures 1,404°–1,503°F, fuel flow 13.1 gph, rpm 2,415, manifold pressure 23.4 inHg, oil pressure 39 psi, and oil temperature 123°F. The attitude indicator was removed and examined; its glass face was intact with slight scratching, no significant deformation, gimbals moved freely, gyro rotor spun freely, with wetness and corrosion but no scoring or gouges.