What happened
On 1 November 2022, an AW109SP helicopter, registration G-RAYN, was performing a non-commercial flight near Llanelidan, Denbighshire. The flight, which was intended to be a daytime operation, was delayed until after nightfall. While attempting a vertical departure from an unlit field landing site, the aircraft began an unintended rearward drift.
At an altitude of approximately 40 feet, the main rotor blades struck a stand of trees, causing catastrophic damage to the rotor system. The helicopter fell to the ground and came to rest on its side. While the fuel tanks remained intact and no fire occurred, the impact caused significant damage to the airframe, including the separation of the tail boom. Of the six people on board, the pilot was uninjured, but the passengers sustained injuries, including one serious injury and four minor injuries.
The investigation
The AAIB investigation examined the operational circumstances, the pilot's pre-flight preparations, and the aircraft's technical condition. Investigators found no technical faults with the helicopter's engines or systems. The inquiry focused on the transition from a planned day flight to a night operation and the lack of visual references during the climb.
Investigators also reviewed the pilot's weight and balance calculations and the passenger safety procedures. It was noted that several passengers had not fastened their seatbelts prior to departure. The investigation also looked into the operator's safety management systems, specifically regarding night flying training and the management of landing site risks.
Findings
- The primary cause of the accident was the unintended rearward transition of the helicopter into trees during a night departure from an unlit site.
- Visual references, including the horizon and lights from a nearby lodge, were insufficient for the pilot to detect the backward drift.
- Distraction and time pressure led to incomplete weight and balance calculations, which may have resulted in the aircraft being overweight at takeoff.
- Operational barriers, such as a misunderstanding of landing site restrictions and a lack of proactive planning for delays, contributed to the unsafe departure conditions.
- The lack of secured seatbelts for several passengers likely contributed to the severity of the injuries sustained.
Safety action
Following the accident, the operator implemented several measures, including:
- Developing a new Integrated Management System and a specific risk assessment for night off-airfield operations.
- Procuring deployable lighting sets to mitigate risks during unscheduled night departures.
- Implementing an annual night flying training programme for all pilots, covering night procedures and site surveys.
- Updating the Operations Manual to clarify responsibilities regarding landing site compliance and passenger safety briefings.