Accident Overview
On August 9, 2010, at approximately 1442 Alaska daylight time, a single-engine, turbine-powered, amphibious float-equipped de Havilland DHC-3T airplane (registration N455A) impacted mountainous, tree-covered terrain about 10 nautical miles northeast of Aleknagik, Alaska. The airplane was operated by GCI Communication Corp. of Anchorage, Alaska, under 14 Code of Federal Regulations Part 91.
Flight Details
The flight departed around 1427 from a GCI-owned private lodge on the shore of Lake Nerka, en route to a remote sport fishing camp about 52 nautical miles southeast on the Nushagak River. The purpose was to transport lodge guests to the fishing camp. No flight plan was filed. The accident pilot had flown the same airplane earlier that day to Dillingham Airport and back.
Weather Conditions
Around the time of the accident, Dillingham Airport (about 18 nm south) reported marginal visual flight rules conditions. The pilot had previously reported ceilings at 500 feet, visibility 2-3 miles in light rain, and continuous light chop turbulence. Later, the lodge manager noted broken ceilings about 2,000 feet agl with blue patches and good visibility at departure. One passenger described visibility as fine at takeoff, but another reported white-out conditions after becoming airborne.
Passenger Accounts
Several passengers provided accounts. One in the right cockpit seat stated the pilot deviated from the usual route to avoid wind and weather. Another passenger fell asleep soon after takeoff. A third reported fog below the airplane but did not believe they flew into clouds. A fourth saw white-out conditions and could not see the ground. The last awake passenger stated the pilot stayed below clouds, flew along tree lines and streams, then banked into a left turn before immediate terrain impact, with no unusual engine noises or maneuvering prior.
Terrain and Wreckage
The wreckage was found at an elevation of about 950 feet msl in steep, wooded terrain in the Muklung Hills, approximately 16 nm southeast of the GCI lodge.
Probable Cause
The official probable cause was the pilot's temporary unresponsiveness for reasons that could not be established from the available information. Contributing to the inability to determine exactly what occurred was the lack of a cockpit recorder system with the ability to capture audio, images, and parametric data.