Single-engine aircraft crash in mountainous terrain

1 fatality • Port Alsworth, United States of America • Flight

A turbine-powered, single-engine airplane crashed into a snow-covered mountain during a cross-country flight, following a period of flight through deteriorating weather.

What happened

A pilot was performing a cross-country flight to a family home in a turbine-powered, single-engine airplane. Prior to departure, the pilot had communicated with a relative via text and was aware of windy conditions, though mountain peaks appeared clear. However, the pilot did not obtain an official preflight weather briefing and had not checked weather cameras. Available weather data indicated potential low-altitude turbulence and icing risks above 12,000 feet, while cameras would have shown declining visibility due to snow and mountain obscuration shortly before the flight began.

During the flight, radar tracked the aircraft climbing from 4,600 feet to 14,700 feet before a westward turn over the mountains. Text messages sent by the pilot during the climb noted that the intended mountain pass was obscured, leading to a plan to fly over the peaks and descend through cloud gaps later. Radar data showed the aircraft remained above 12,500 feet for approximately 30 minutes and above 14,000 feet for another 14 minutes before beginning a gradual descent. The aircraft eventually struck a steep, snow-covered mountain face. The wreckage showed the right wing had separated, and the cockpit and forward fuselage sustained heavy damage, suggesting an impact during forward flight. There were 0 fatalities reported in the source, though the wreckage was not recovered for full examination due to the hazardous environment.

Findings

Investigation of the weather conditions revealed that cloud layers in the area were thickening in the 30 minutes preceding the accident. It is believed the aircraft was operating in icing conditions despite not being certified for such environments, which may have caused structural or induction icing leading to an uncontrolled loss of altitude. Additionally, the aircraft operated at altitudes exceeding 12,500 feet for over 30 minutes without evidence of supplemental oxygen equipment, meaning the pilot may have been affected by hypoxia, though this could not be confirmed.

Probable cause

The aircraft likely encountered icing conditions and deteriorating weather, potentially leading to an uncontrolled loss of altitude.

Frequently asked questions

What happened in the 2016-10-28 Pilatus PC-6 (Porter & Turbo Porter) accident near Port Alsworth, United States of America?

A turbine-powered, single-engine airplane crashed into a snow-covered mountain during a cross-country flight, following a period of flight through deteriorating weather.

Were there any fatalities in the 2016-10-28 Pilatus PC-6 (Porter & Turbo Porter) accident?

The accident was fatal, resulting in 1 fatality.

What aircraft was involved and where did it happen?

The accident on 2016-10-28 involved a Pilatus PC-6 (Porter & Turbo Porter), registration N5308F, operated by Highland Air, at Port Alsworth, United States of America.

What was the probable cause of the accident?

The aircraft likely encountered icing conditions and deteriorating weather, potentially leading to an uncontrolled loss of altitude.

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