Investigation Summary
Rescue 116 was tasked to provide 'top cover' for another helicopter, Rescue 118, which was performing a medical evacuation of a fisherman from a vessel 140 miles off the west coast of Ireland. The crew planned to refuel at Blacksod Lighthouse before heading out to sea. During the approach to Blacksod, the crew utilized a pre-programmed flight path stored in the Flight Management System (FMS). This route, known as 'Blacksod South', brought the helicopter directly over Blackrock Island. Although the island was marked on paper charts and the GPS mapping system, it was missing from the EGPWS obstacle database used by the crew for terrain alerts. As the helicopter flew at an altitude of 200 feet in low cloud and mist, the crew remained unaware of the terrain until seconds before impact. The winchman, monitoring the radar, identified a target and called out 'island' followed by 'come right now'. The crew attempted an immediate evasive maneuver, but the tail of the helicopter struck the terrain of the island near the lighthouse, causing the aircraft to spin out of control and crash into the sea.
Final Conclusions
The Air Accident Investigation Unit (AAIU) released its final report on 5 November 2021. The investigation concluded that the probable cause was the crew's lack of awareness regarding the 282-foot obstacle in their flight path while flying at 200 feet at night in poor weather. Contributing factors included the omission of Blackrock Island from the EGPWS database, deficiencies in the operator's route design and safety management systems, and inadequate oversight of the search and rescue contract. As a result of the investigation, the AAIU issued 42 safety recommendations to various bodies including the operator and the Irish Coast Guard.
Video Analysis
Rescue helicopter crashes in atlantic during Rescue mission ... — In the early hours of 14 March 2017, a Sikorsky S-92 helicopter operated by CHC Helicopter under contract to the Irish Coast Guard (call sign Rescue 116) crashed into Blackrock Island.
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Systems & Failure Modes
EGPWS
Enhanced Ground Proximity Warning System; a Class A terrain awareness system that failed to alert the crew because Blackrock Island was not in its obstacle database.
FMS
Flight Management System; the crew used a pre-programmed 'Blacksod South' route that led the aircraft directly over the island.
Interesting Facts
- 01Blackrock Island was registered in the GPS mapping system but was missing from the EGPWS terrain database.
- 02The helicopter was flying at 200 feet, while the highest point of Blackrock Island is 282 feet.
- 03The AAIU found no evidence of mechanical failure or anomalies in the flight recorder data.
- 04The search involved over 110 fishing vessels, making it one of the largest sea searches in Irish history.
- 05While four fatalities were confirmed, the two rear crew members were never located and remain lost at sea.
Safety Actions & Advisories
EGPWS Database Audit
A review of terrain and obstacle databases was initiated to ensure all offshore islands and lighthouses were accurately represented.
SAR Route Review
The operator and Irish Coast Guard conducted a comprehensive review of all pre-programmed search and rescue flight paths to identify and mitigate terrain hazards.
Known Controversies & Unanswered Questions
Final Report Review Delay
Reference ↗The final report was delayed by two years after an interested party requested a formal review of the draft findings, the first such review in the AAIU's history.