AIRBUS AS350 near Deadhorse, AK — 2015-10-27

Probable cause

The noninstrument-rated pilot's continued visual flight into adverse weather conditions, which resulted in spatial disorientation, and his subsequent failure to maintain terrain clearance while attempting to land in flat light and whiteout conditions.

NTSB narrative

According to the noninstrument-rated commercial pilot, he was flying the helicopter, which was not instrument flight rules capable, to the landing site to pick up a crew of four seismic workers. Before the accident, he conducted a preflight risk assessment, which noted that the area was conducive to whiteout conditions and that visibility was between 1 and 3 statute miles. The assessment fell within the "low risk go flying" category, and a visual flight rules company flight plan was filed. The pilot reported that, while en route to the landing site, the weather began deteriorating and that he encountered an area with flat light conditions over snow-covered ground. The pilot then slowed the helicopter and stayed low to the ground. While slowing down to land, blowing snow from the main rotor downwash subsequently reduced the visibility to whiteout conditions with no ground reference, which likely led to the pilot experiencing spatial disorientation. The helicopter's right skid then contacted the ground, and the helicopter slid right and then rolled onto its right side. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. The National Transportation Safety Board has issued safety recommendations noting the importance of pilots being instrument proficient and of aircraft operating in such conditions being equipped with radar altimeters to enhance situational awareness; the accident pilot was not instrument rated and the accident helicopter was not equipped with a radar altimeter. Although the pilot was conducting the flight for a Canadian operator, which would not have been subject to these recommendations, this accident demonstrates the importance of pilots and helicopters being properly equipped to handle operations in such conditions.

Analysis

Primary failure mode

Controlled flight into terrain

First missed decision gate

Pilot should have aborted the approach due to deteriorating weather conditions.

NTSB coding

• VFR encounter with IMC · Approach
• Attention / Monitoring
• Decision Making / Judgment
• Experience / Qualifications
• Spatial Disorientation

Evidence available

• Photos
• 4 docket documents

Docket documents4

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Pilot's Statementinterview
• NTS Safety Recommendations A-02-33 to A-02-35other
• Accident Photos (Courtesy of Operator)photos

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