Flight Plan Change and Wirestrike
A pilot flying a helicopter on a cattle mustering operation initially planned to direct a stockperson to a small herd and return to base. However, upon spotting additional cattle, the pilot altered the plan and decided to muster the original herd to the main yards. The pilot was aware of powerline locations at the main yards from previous operations, but that knowledge was from a significant period earlier, making the wires unlikely to be front of mind during the approach. Recorded flight data showed the helicopter had overflown the yards once in previous days, but at a height well above the wires, and there was no plan to use the yards at that time. No subsequent flights over or around the yards occurred that would have allowed hazard reassessment prior to the accident flight.
On the accident flight, the pilot flew south from the yard entrance, likely intending to land and open a second gate for cattle entry. The single-wire earth return (SWER) line crossing the yard was very difficult to detect due to lack of contrast with the background, the next power pole being outside the pilot's normal field of view in the direction of flight, and absence of markers on the SWER line. Additionally, power poles from a 3-strand network were in the pilot's forward view; while also hard to see, if noticed they might have given a false assurance that no wires were in the immediate operating area.
Contact and Terrain Collision
Marks on the left skid indicated it contacted the SWER line at an oblique angle, with the wire rubbing along the skid toward the front crosstube and then away. The relatively low forward airspeed likely prevented the wire from being severed. It could not be determined whether the pilot observed the wire before contact and attempted avoidance, or reacted only at the moment of impact.
After contacting the wire, the helicopter collided with terrain and came to rest inverted. It then rolled over, and the front of the right skid collapsed under the fuselage as the helicopter came to rest on its right side.
Emergency Locator Transmitter Status
The ELT remote switch in the cabin was in the ARMED position, so the pilot likely believed the system was operational. However, the transmitter was selected to OFF. Why it was deactivated and not detected via periodic self-testing could not be determined. In this instance, the ELT status had no effect on the outcome as wreckage was located quickly due to a nearby witness.