What happened
On 30 May 2018, a Bell 206B3 helicopter, registration G-OPEN, was performing a private flight from Husthwaite to Walton Wood Airfield for a scheduled maintenance check. The flight took place during challenging weather conditions characterized by low cloud and reduced visibility.
Witnesses observed the aircraft flying normally at a low level before it performed a steep climb into the cloud. While inside the cloud, the aircraft was heard making a loud, heavy sound. Upon emerging from the cloud, the helicopter was seen rotating through approximately 540 degrees before entering a rapid descent. The aircraft struck the ground in a relatively level attitude, causing the airframe to become inverted and catch fire. The pilot sustained 1 fatal injury.
The investigation
The AAIB examined the wreckage and the engine components. The investigation found no evidence of pre-existing mechanical defects in the helicopter or its Allison 250-C20J engine that would have prevented normal operation. While the engine's axial compressor had separated from the impeller, this was determined to be a result of the extreme forces experienced during the ground impact rather than a pre-impact failure.
Investigators also reviewed the pilot's flying history and the meteorological conditions. The pilot had not flown for 77 days prior to the accident and was not qualified to fly in instrument meteorological conditions. Radar data showed the aircraft's altitude and speed fluctuated significantly in the moments leading up to the accident, including a climb to 1,020 ft amsl.
Findings
- The primary cause of the accident was likely spatial disorientation following the inadvertent entry into cloud.
- The pilot's lack of recent flying experience likely increased the difficulty of managing the aircraft in degraded visual conditions.
- The decision to proceed with the flight was influenced by the perceived need to meet a maintenance deadline and personal scheduling commitments.
- The challenging weather, involving low cloud bases and reduced visibility, significantly increased the operational risk.