Pilot Debrief

Aerospatiale AS355 near Rifle, CO — 2020-07-11

Final reportCEN20LA273
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Date
2020-07-11
Location
Rifle, CO, USA
Aircraft
Aerospatiale AS355
Registration
N708AC
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Hover

Probable cause

A loss of tail rotor effectiveness, the pilot’s subsequent loss of helicopter control, and collision with terrain.

NTSB narrative

The pilot of the helicopter was maneuvering at a low altitude to conduct his first aerial observation flight of the day. The passenger, who was a camera operator for the flight, reported that the pilot began a hover over the electrical substation while they discussed a plan for the flight. While in a low altitude hover, the helicopter began swaying left and right, then spinning in a counterclockwise (left) direction. Shortly thereafter, the helicopter impacted the terrain. The pilot had no recollection of the accident. Witness observations indicated that the helicopter’s final impact was immediately followed by a postcrash fire that destroyed the helicopter. Postaccident examination of the helicopter and engine revealed no evidence of mechanical anomalies that would have precluded normal operation. The helicopter was operating at a gross weight of 5,040 lbs, and the maximum allowable gross weight is 5,291 lbs. The calculated density altitude was 6,566 ft mean sea level. The accident helicopter’s flight characteristics at the time of the accident would have included slow airspeed, a high-power setting, that were all conducive to a loss of tail rotor effectiveness (LTE), thus it is likely that the loss of control was the direct result of LTE.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have aborted the hover before losing control.

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 14 docket documents
View NTSB final reportView NTSB docket

Docket documents14

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