Flight History
On October 28, 2016, at approximately 1828 Alaska daylight time, a Fairchild Heli-Porter Pilatus PC-6, registration N5308F, impacted mountainous terrain about 57 miles north-northeast of Port Alsworth, Alaska. The commercial pilot was fatally injured, and the airplane sustained substantial damage. The airplane was registered to Highland Air LLC and operated by the pilot under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the departure and destination airports, with areas of reduced visibility and lower cloud ceilings along the route. No flight plan was filed for the personal flight, which departed Lake Hood Seaplane Base (LHD), Anchorage, at 1711, destined for a private airstrip near Port Alsworth.
The purpose of the flight, according to a family member, was to transport fuel to the family residence on Lake Clark. The pilot had delivered fuel the previous day and returned to Anchorage that morning. The pilot was familiar with routes through the mountains, typically using Lake Clark Pass or the northern Merrill Pass. Before departure, the pilot exchanged text messages with a family member about weather conditions, including a message stating that the pass looked "fuzzy." The last message from the pilot was: "On my way. Holes out west."
Primary radar data from the FAA Anchorage Air Route Traffic Control Center showed the airplane departing LHD at about 1711. It climbed to 5,600 ft mean sea level (msl), then descended to 4,600 ft before climbing to 14,700 ft, making "S" turns. About 1810, at 13,200 ft, the airplane turned northwest and began a descent, continuing for about 25 miles to the last recorded altitude of 7,600 ft at 1827, about 2 miles southeast of the accident site. No voice communications were recorded. A 406-MHz emergency locator beacon (ELT) signal was received about 1831. Search efforts by the Alaska Rescue Coordination Center, Alaska Air National Guard, and Civil Air Patrol continued for days. The ELT signal stopped on October 30. The wreckage was located on November 3 on the south side of a steep, snow-covered mountain at about 6,500 ft msl.
Pilot and Aircraft Information
The pilot, aged 55, held a commercial pilot certificate with ratings for airplane single-engine land and sea, and instrument airplane. He held a second-class FAA medical certificate issued April 1, 2016, with a limitation requiring glasses for near vision. On the application, he reported 6,400 total flight hours and 43 hours in the previous 6 months.
The high-wing, conventional-gear, turbine-powered airplane was manufactured in 1975 by Fairchild Heli-Porter under Pilatus design authority. It was equipped with a 575-shaft horsepower Garrett AiResearch TPE331-1-151K turbine engine and a three-bladed Hartzell metal propeller. The airplane had an Artex ELT model ME406, a radar altimeter, and an internal 250-gallon fuel transport tank. There was no evidence of supplemental oxygen equipment. Engine, airframe, and propeller logbooks were on the airplane but not located after the accident. A friend who was a mechanic stated the airplane was in very good condition; he had recently repaired an electrical issue preventing engine starting.
Meteorological Conditions
No record existed of the pilot receiving a weather briefing from FAA facilities or from DUAT. The National Weather Service (NWS) Alaska Aviation Weather Unit forecast charts valid for the day indicated an occluded frontal system, with expected light rain and increasing southeasterly winds near the accident site. VFR conditions were forecast for the planned and actual routes. Icing and turbulence forecasts indicated potential moderate turbulence below 4,000 ft and isolated severe turbulence below 6,000 ft, and isolated moderate icing from 12,000 ft to FL200.
Nearest weather observation for the intended destination (Port Alsworth Airport) at 1650 reported wind from 060° at 10 knots, visibility 30 miles, overcast ceiling at 10,000 ft. The nearest observation to the accident site (Sparrevohn Airport) at 1755 reported wind from 140° at 20 knots gusting to 41 knots, visibility 10 miles, overcast ceiling at 8,500 ft. A remote automated weather system station about 13 miles west-southwest of the site reported north wind at 6 knots with gusts to 17 knots, temperature 41°F, and relative humidity 83%. Archived FAA weather camera images at nearby passes showed deteriorating weather starting about 1530 with visibilities 1 mile or less in snow showers and obscured terrain by 1600. The Lake Clark Pass West view at 1838 showed clouds above highest terrain and unrestricted visibility. Upper air sounding from NWS Anchorage indicated potential for moderate rime icing at 9,330 ft. Radar data from the NWS confirmed a layer of altostratus to nimbostratus clouds over the route and accident site with likely snow showers. Sunset was at 1807, end of civil twilight at 1853.
Wreckage and Impact
The accident site was located in steep, mountainous, snow-covered terrain in the Neacola mountains of the Alaska Range, about 6 miles south of Merrill Pass west and 14 miles northeast of Lake Telaquana. The airplane came to rest on the south side of an east-west ridge at about 6,500 ft, mostly covered by 3 ft of snow. The forward fuselage and cockpit were torn away and partially separated from the aft section forward of the wing roots. The forward fuselage and engine were displaced aft and right with significant crush damage. The right wing was missing; the left wing was partially attached and displaced downward. The empennage was intact; the rudder was fractured about 3 ft from the top. Jet A fuel was present on recovered items. A Garmin GPSMAP 396 and a personal electronic device were recovered. The airplane was not recovered due to hazardous terrain and snow. On July 8, 2017, an overflight showed the wreckage had slid about 100 ft down the mountain. Left and right wings were separated near the wing roots, about 100 ft above the fuselage. All primary airplane components were present.
Additional Information
The Neacola Mountains are a rugged range between south central and south interior Alaska, with peaks up to 11,413 ft. Two primary passes exist: Lake Clark Pass (course about 220°) and Merrill Pass about 32 miles north with higher terrain and narrow canyons.
Regarding icing, the PC-6 Airplane Flight Manual states that flying into predicted or actual icing conditions is not approved. Federal Aviation Regulation 91.211 requires supplemental oxygen for crew above 12,500 ft for more than 30 minutes and always above 14,000 ft. The accident airplane was unpressurized; radar data indicated operation above 12,500 ft for 31 minutes and above 14,000 ft for about 14 minutes, with no supplemental oxygen on board. Hypoxia effects can degrade cognitive skills and judgment.
Medical and pathological examination by the Alaska State Medical Examiner attributed the pilot's cause of death to multiple blunt force injuries. Forensic toxicology by the FAA tested negative for carbon monoxide, cyanide, ethanol, and listed drugs.
Examination of the recovered Garmin GPSMAP 396 revealed data up to October 24, 2016, but no data from the accident flight. The personal electronic device was passcode-protected and data was not recovered.