Agusta A109A II crashes into Mourne Mountains

Casualties unknown • Shanlieve, Mourne Mountains, Northern Ireland, GB

An Agusta A109A II helicopter crashed into the western face of Shanlieve in Northern Ireland, resulting in three fatalities.

What happened

On 23 October 2010, an Agusta A109A II helicopter, registration N2NR, was conducting a private flight from a site near Bagshot, Surrey, to Caernarfon, Wales. The flight included the pilot and two passengers. After refueling at St Angelo Airport, Ennisklen, the aircraft proceeded toward its destination.

Radar data and GPS tracking indicated the helicopter maintained a steady groundspeed of approximately 150 kt. During the flight, the aircraft performed several heading changes. At one point, the helicopter turned left toward Newry and climbed to 2,000 ft, before turning right to resume its original track.

While flying through the Mourne Mountains, the aircraft struck the western slope of Shanlieve at an altitude approximately 100 ft below the summit. The impact was high-speed, and the aircraft was destroyed. All three fatalities occurred during the crash.

The investigation

The AAIB investigation examined radar data, GPS-based Spidertracks information, and wreckage recovered from the site. Although the airframe was severely disrupted, investigators found no evidence of mechanical failure in the engines or rotors.

Analysis of the onboard avionics revealed that the Enhanced Ground Proximity Warning System (EGPWS) had not been powered up since its installation in late 2009. The investigation also reviewed the pilot's navigation aids, including a Skymap IIIC and Garmin GPS units. The Skymap system used color coding for terrain, but because it did not display spot heights, terrain above 2,000 ft was not modeled in the database.

Meteorological data showed that at the time of the accident, the area was experiencing an unstable airflow with broken cloud and light rain showers. Witnesses, including hill walkers in the area, reported seeing the helicopter in or near cloud cover.

Findings

  • The helicopter flew into the terrain at a constant altitude and heading.
  • The upper slopes of the Shanliente ridge were likely obscured by cloud.
  • The pilot may have believed the terrain ahead was clear due to the lack of specific terrain elevation data on the Skymap IIIC display.
  • The EGPWS was found in the off position and had not been used during the flight.
  • Visual or distracting factors, or potential subtle incapacitation, may have prevented the pilot from recognizing the rising ground.

Probable cause

The accident was likely caused by the pilot flying into high terrain that was obscured by cloud, potentially due to a reliance on navigation aids that did not clearly indicate ground elevations above 2,000 feet.

Frequently asked questions

What happened in the 2010-10-23 Agusta A109A II accident near Shanlieve, Mourne Mountains, Northern Ireland, GB?

An Agusta A109A II helicopter crashed into the western face of Shanlieve in Northern Ireland, resulting in three fatalities.

What aircraft was involved and where did it happen?

The accident on 2010-10-23 involved a Agusta A109A II, registration N2NR, at Shanlieve, Mourne Mountains, Northern Ireland, GB.

What was the probable cause of the accident?

The accident was likely caused by the pilot flying into high terrain that was obscured by cloud, potentially due to a reliance on navigation aids that did not clearly indicate ground elevations above 2,000 feet.

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