Pilot Debrief

GARLICK HELICOPTERS INC OH-58A+ near Alpine, AL — 2021-06-25

Final reportERA21LA269
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Date
2021-06-25
Location
Alpine, AL, USA
Aircraft
GARLICK HELICOPTERS INC OH-58A+
Registration
N372NS
Category
Helicopter
Highest injury
Fatal
Fatalities
1
Phase of flight
Maneuvering

Probable cause

The pilot’s failure to maintain clearance from powerlines during a low-level aerial application flight, resulting in main rotor blade impact with a fiber-optic cable, a loss of control, and the helicopter’s subsequent impact with terrain.

NTSB narrative

The pilot had completed multiple aerial application flights over a cornfield on the day of the accident. During the accident flight, the helicopter contacted a fiber-optic cable that was collocated with high-voltage transmission lines. The wire strike resulted in a loss of control, and the helicopter impacted terrain, fatally injuring the pilot and substantially damaging the helicopter. A video recording of the helicopter during a previous application flight that day revealed that the helicopter was flying at low altitude and below the trees and powerlines that surrounded the field. After each pass over the field, the helicopter gained altitude to clear the surrounding trees and powerlines, turned back, and then descended again below the trees and powerlines for the next pass. Also, a witness heard a helicopter that sounded as if it was flying “real low,” but she could not see the helicopter because of trees. The witness reported that she heard a sound “like propellers hitting a tree, and then a boom like an explosion.” No evidence indicated a preimpact mechanical malfunction or anomaly that would have precluded normal operation of the helicopter. Postaccident examination of the wreckage revealed that one of the main rotor blades displayed an area, on the outboard section of the blade, that contained leading-edge damage, a wire strike signature about 8 inches inboard of the blade tip and scratching oriented at an angle that was about 45°-from the tip inward and toward the trailing edge. The other main rotor blade was missing about 3 1/2 ft of the outboard portion of the blade. These observations were consistent with the helicopter being in a right turn when the main rotor blades contacted the fiber-optic cable. It is likely that the pilot lost positional awareness during the turnaround at the end of the final application pass. Also, because the helicopter was not equipped with a wire strike prevention system and the transmission lines did not have fixed aerial obstruction features such as wire markers, which would have made the transmission lines more visible, the pilot’s attention was not likely drawn to the wires before the wire strike. Additionally, even though the helicopter was equipped with a wire strike protection system, the areas of damage on the outboard portions of the main rotor blades indicated that the contact with the fiber-optic cable likely occurred outside of the effective angle of the cable cutters.

Analysis

Primary failure mode
Controlled flight into terrain
First missed decision gate
Pilot could have avoided low-level flight near power lines.

NTSB coding

Evidence available

  • Video
  • Photos
  • 9 docket documents
View NTSB final reportView NTSB docket

Docket documents9

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