Pilot Debrief

AIRBUS AS350 near Delta Junction, AK — 2017-08-03

Final reportANC17CA041
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Date
2017-08-03
Location
Delta Junction, AK, USA
Aircraft
AIRBUS AS350
Registration
N351SH
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

The pilot’s failure to maintain clearance from a steel frame attached to a tracked drilling unit. Contributing to the accident was the pilot’s failure to visually identify the steel frame during the reconnaissance process.

NTSB narrative

The helicopter pilot reported that he was transporting a passenger to a remote drilling site where a tracked drilling unit was stationed. He reported that he landed into the wind, which necessitated descending over bordering trees into the drilling site. The helicopter touched down on the dirt, and upon lowering the collective, he reported that he heard a "bang," and the helicopter slowly started to "pick up a ground wobble." The pilot shut down the helicopter, and both occupants exited without further incident. A postaccident inspection revealed that the blue and red main rotor blades sustained substantial damage from impacting a black 1.5-inch steel frame attached to the tracked drilling unit, which is used to mount a canvas weather shelter for the drilling crews. The pilot reported that the steel frame was not visible to him from above as he was descending into the drilling site. The pilot further reported that he had made multiple landings at the drilling site in the past 3 months and that, with the previous landings, he had landed farther past the tracked drilling unit, and the steel frame was always behind the helicopter. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. The Federal Aviation Administration Helicopter Flying Handbook (FAA-H-8083-21A, 2012) discusses high and low reconnaissance procedures and states, in part: The purpose of conducting a high reconnaissance is to determine direction and speed of the wind, a touchdown point, suitability of the landing area, approach and departure axes, and obstacles for both the approach and departure. A low reconnaissance is accomplished during the approach to the landing area. When flying the approach, verify what was observed in the high reconnaissance, and check for anything new that may have been missed at a higher altitude, such as wires and their supporting structures (poles, towers, etc.), slopes, and small crevices.

Analysis

Primary failure mode
Human factors
First missed decision gate
Conducting a proper low reconnaissance to identify obstacles before landing.

NTSB coding

Evidence available

  • Photos
  • 2 docket documents
View NTSB final reportView NTSB docket

Docket documents2

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