What happened
On February 18, 2013, a Bell 206B helicopter, registration N20620, crashed near Eureka, Nevada, while performing a seed-dispersal mission for the Bureau of Land Management. The flight was part of an aerial reseeding project intended to restore areas damaged by the 2012 Pinto Fire.
The pilot had been conducting low-level operations, flying between 100 and 200 feet above the ground, throughout the day. Earlier that morning, the pilot had performed reconnaissance with a BLM manager, during which the presence of two sets of power transmission lines was discussed. The pilot noted the existence of a third set of lines in the area.
At approximately 14:23, the helicopter was performing a seed application run. During the maneuver, the aircraft struck a static line located above a set of power transmission lines. The collision resulted in 1 fatality.
The investigation
Investigators examined the wreckage and found the helicopter sustained significant damage, including a severed tailboom and crush damage from the nose to the aft bulkhead. The main rotor blades exhibited gouges consistent with striking the severed static line. The engine and airframe showed no evidence of mechanical failure or malfunction prior to the impact.
The aircraft was equipped with a seed spreading system attached to the belly hook, which hung approximately 11 feet below the skids. The helicopter was not equipped with a wire strike protection system.
Data from the Ag-Nav agricultural navigation system confirmed the helicopter had completed 20 successful passes over the area, frequently flying directly over the power lines. The final recorded data showed the aircraft was climbing and transitioning into a right turn for a new application run at the time of the collision.
Analysis of the pilot's recent flight history showed he had accumulated 40.5 flight hours over the preceding five days. While this was within the specific limits of the Department of the Interior contract, it exceeded the flight time recommendations used by the U.S. Army for low-level and "nap of the earth" operations.
Findings
- The power transmission lines and static lines were not equipped with visibility markers.
- The static lines were thinner in gauge and could have been obscured by the terrain.
- The pilot was aware of the transmission lines in the area but failed to maintain clearance from the static line.
- The pilot was likely experiencing task- and/or work-related fatigue due to the high concentration required for low-altitude, repetitive flight operations.