Aviation Accident Summaries

Aviation Accident Summary ANC06LA025

Ilimana, AK, USA

Aircraft #1

N7528Z

Robinson R44

Analysis

The commercial helicopter pilot was flying one passenger on an on-demand, Title 14, CFR Part 135 air taxi flight to a remote site in an area surrounded by snow-covered, flat, featureless terrain. Low fog, reduced visibility, and flat light conditions reduced his ability to discern a horizon or terrain. He said that the visibility deteriorated to about 1 or 2 miles, and he was unable to discern any topographic features on the snow-covered terrain, and he elected to make a precautionary landing to wait for better visibility. After about 10 minutes, he decided to continue to his destination. Just after takeoff, flat light conditions again reduced his ability to recognize any topographical features on the snow-covered terrain. He reported that while he was attempting to establish a stable hover, and erroneously believing that the helicopter was not moving, the helicopter's right skid struck the snow-covered terrain. The helicopter rolled to the right, and the main rotor blades struck the ground. As the main rotor blades struck the ground, the helicopter rolled onto its right side. The helicopter sustained substantial damage to the fuselage, tail boom assembly, and the main and tail rotor drive systems. The pilot reported that there were no preaccident mechanical anomalies with the helicopter.

Factual Information

On March 12, 2006, about 1320 Alaska standard time, a skid-equipped Robinson R44 helicopter, N7528Z, sustained substantial damage after colliding with snow-covered terrain while maneuvering to land, about 10 miles west of Iliamna, Alaska. The helicopter was being operated as a visual flight rules (VFR) on-demand charter flight by Pollux Aviation, Wasilla, Alaska, under Title 14, CFR Part 135, when the accident occurred. The certificated commercial pilot and the sole passenger were not injured. Instrument meteorological conditions prevailed at the accident site. Visual meteorological conditions prevailed at the time of departure, and company flight following procedures were in effect. The flight originated about 1305, from the Iliamna Airport, Iliamna, and was en route to a remote, off-airport site. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on March 12, the pilot said that after departing from the Iliamna Airport, he flew west, en route to a remote drill site. According to the pilot, low fog, reduced visibility, and flat light conditions reduced his ability to discern a horizon or terrain. He said that the visibility deteriorated to about 1 or 2 miles, and he was unable to discern any topographic features on the surface of the flat, featureless, snow-covered terrain, and he elected to make a precautionary landing to wait for better visibility. After remaining on the ground for about 10 minutes, he decided to fly towards his destination. He said that just after takeoff, as the helicopter moved forward, flat light conditions and blowing snow, contributed to his inability to recognize any topographical features. He reported that while he was attempting to establish a stable hover, and erroneously believing that the helicopter was not moving, the helicopter's right skid struck the snow-covered terrain. The helicopter subsequently rolled to the right, and the main rotor blades struck the ground. As the main rotor blades struck the ground, the helicopter continued to roll onto its right side. The helicopter sustained substantial damage to the fuselage, tail boom assembly, and the main and tail rotor drive systems. In a written statement included in the NTSB Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the operator, dated March 20, 2006, the pilot reported weather conditions at the time of the accident to be, in part: Wind, calm; visibility, 3 statute miles; ceiling and clouds, 100 feet scattered, 200 feet overcast; temperature, 23 degrees F.

Probable Cause and Findings

The pilot's continued flight into adverse weather conditions, and his spatial disorientation and loss of control during a subsequent landing attempt. Factors associated with the accident are flat light and whiteout conditions, fog, and snow-covered terrain.

 

Source: NTSB Aviation Accident Database

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