What happened
On 18 February 2009, an Eurocopter EC225 LP Super Puma, registration G-REDU, was conducting a scheduled night flight in support of North Sea oil and gas operations. The aircraft departed Aberdeen Airport for the ETAP oil production platform. While the flight was initially uneventful, the crew received updated weather information approximately 30 minutes from the platform indicating deteriorating conditions, including reduced visibility and a lowering cloud base.
To maintain visual contact with the platform, the crew decided to perform an Airborne Radar Approach. During the descent, the helicopter entered a bank of fog. The crew attempted to maintain visual references by descending to 500 ft, then 300 ft, and eventually 400 ft as they navigated the fog. At a distance of approximately 0.75 nm from the ETAP platform, the commander disengaged the autopilot to fly manually. While the co-pilot believed he had visual contact with the helideck lights, the commander could not identify the deck.
As the aircraft turned left toward the platform, the rate of descent increased. Flight data shows the helicopter entered a nose-up pitch attitude, with the airspeed dropping significantly. At 1.75 ft above the sea surface, the EC2 and25 struck the water. The impact caused the tail boom to detach, and the remaining fuselage eventually became inverted.
The investigation
The AAIB conducted an Inspector’s Investigation, supported by the French BEA. Investigators recovered the wreckage from the seabed using Remotely Operated Vehicles (ROVs). Analysis of the Combined Voice and Flight Data Recorder (CVFDR) provided critical details regarding the aircraft's final moments, including the descent profile and the lack of specific terrain warnings during the impact phase.
Findings
- The aircraft struck the sea surface approximately 500 metres south of the ETAP platform.
- The impact with the water caused the tail boom to separate from the main fuselage.
- There was no evidence of a pre-impact malfunction in major mechanical components, such as the engines or rotors.
- While the crew had previously observed a TAWS 'caution' during the cruise, no 'CHECK HEIGHT' or 'ONE HUNDRED FEET' audio warnings were recorded during the final approach.
- The aircraft's airspeed had reduced to 24 kt just seconds before the recording ended, indicating a loss of sufficient airspeed to sustain flight.
Safety action
Following the accident, the operator updated its Operations Manual procedures regarding offshore night operations, specifically concerning the criteria for stable approach configurations.