MCDONNELL DOUGLAS HELICOPTER 500N near Honolulu, HI — 2016-09-02

Probable cause

The pilot's failure to maintain helicopter control in gusting wind conditions, which resulted in the helicopter rescue net’s contact with a utility pole and serious injury to an occupant who fell from the rescue net. Contributing to the accident was the pilot’s and rescue personnel’s decision to continue the extraction in proximity to the pole.

NTSB narrative

The helicopter pilot reported that, during a rescue operation to extract a hiker in distress, he flew to a hiking trail lookout where fire department personnel were already present. He observed a utility pole on the east side of the lookout and estimated the wind was about 10-20 kts from the east. The pilot landed the helicopter in a nearby landing zone and prepared the helicopter for a rescue net extraction. The pilot then took off and lowered the rescue net from the 75-100-ft-long line to the injured hiker and firefighter. After they both climbed into the net, the helicopter started to ascend; a strong gust of wind unexpectedly caused the helicopter to ascend too quickly and move laterally toward the utility pole. The pilot attempted to stop the swing of the long line, but the net impacted the utility pole. The firefighter was electrocuted and fell from the net about 20 ft to the ground, which resulted in serious injury. At the time of the accident, the Hawaiian Islands were under the influence of tropical easterly winds, and a hurricane watch had been issued. The surface observations indicated northeast winds of 14-20 kts with peak gusts of 28 kts during the time surrounding the accident. It is likely that the northeast winds produced unfavorable wind conditions over the terrain at the lookout. The operator's "Technical Rescue Standard Operating Guidelines" states, in part, that "[t]eam members and the pilot shall agree that the area they are being inserted into is safe and free of obstructions…"

Analysis

Primary failure mode

Environmental

First missed decision gate

Pilot should have assessed wind conditions more thoroughly before ascent.

NTSB coding

• External load event (Rotorcraft) · Initial climb
• Decision Making / Judgment

Evidence available

• 4 docket documents

Docket documents4

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 - Operatorform
• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 - Pilotform
• Excerpt from the Operator's 'Technical Rescue Standard Operating Guidelines'other
• Record of Email - Meteorologyother

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