Helicopter strikes power lines during filming flight near Porthmadog

Casualties unknown • 2 nm northeast of Portmadog, Gwynedd, GB

An AS350B Ecureuil helicopter struck 11 KV electricity wires while performing low-level filming maneuvers near the Glaslyn River.

What happened

On 18 June 2000, an AS3ymetric 350B Ecureuil, registration G-NUTY, was conducting a private filming mission at a low altitude along the Glaslyn River, approximately 2 nm north-east of Porthmadog, Gwyndd. The aircraft was flying at a height of 50 to 60 feet above the water, level with the surrounding tree line, operating under a CAA exemption from low-flying regulations.

While navigating the river, the pilot identified two wires directly ahead of the aircraft and attempted an immediate climb to avoid a collision. Despite this maneuver, the helicopter struck the wires. The impact occurred at the mid-point of the windscreen, causing the wires to slide back across the airframe, which resulted in the breakage of the OAT probe and produced a flash of sparks and an ozone scent. Following the strike, the pilot performed a precautionary landing in a nearby field and shut down the engines.

The investigation

The investigation examined the damage to the aircraft and the configuration of the electrical infrastructure. Post-flight inspections of G-NUTY revealed superficial scratches to the cabin roof, windscreen, and main gearbox cowling, but no damage to the main rotor mast's dynamic components. The wires had been held against the airframe by the aircraft's nose-up climbing attitude until they snapped against the left-hand hydraulic jack actuator arm.

The investigation established that the wires were 11 KV copper lines supported by poles. The poles were situated within the treeline, with the northern pole positioned roughly 120 feet up a hillside, making the infrastructure difficult to see. The pilot had selected this specific stretch of the river for filming due to the widening water and the absence of visible obstacles or dwellings.

Findings

  • The wires were obscured from view because the supporting poles were hidden within the trees.
  • The pilot did not see the wires or the poles prior to the collision.
  • The aircraft was in a climbing, nose-up attitude at the moment of impact, which caused the wires to slide along the upper surfaces of the airframe.

Probable cause

The pilot failed to identify the 11 KV power lines because the supporting poles were obscured by trees, leading to a collision during a low-level filming maneuver.

Frequently asked questions

What happened in the 2000-06-18 AS350B ECUREUIL accident near 2 nm northeast of Portmadog, Gwynedd, GB?

An AS350B Ecureuil helicopter struck 11 KV electricity wires while performing low-level filming maneuvers near the Glaslyn River.

What aircraft was involved and where did it happen?

The accident on 2000-06-18 involved a AS350B ECUREUIL, registration G-NUTY, at 2 nm northeast of Portmadog, Gwynedd, GB.

What was the probable cause of the accident?

The pilot failed to identify the 11 KV power lines because the supporting poles were obscured by trees, leading to a collision during a low-level filming maneuver.

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