Accident Summary
On 16 September 2021, at 0517 New Zealand Standard Time, an Airbus Helicopters AS350 B3e helicopter, registration ZK-ITD, departed from Lister Helicopters' base near Milton, New Zealand. The purpose was to ferry the helicopter to a cherry orchard near Alexandra for frost protection operations, a distance of 62 nautical miles. The pilot, aged 36, was the sole occupant. The helicopter was destroyed on impact and the pilot did not survive.
Flight History
The flight proceeded normally until near the township of Lawrence. ADS-B data showed a series of turns beginning at 0526:36. The final data point was recorded at 0531:35 at an altitude of 3475 feet. Moments later, the helicopter struck the ground in a near-vertical nose-down attitude at an elevation of about 2430 feet. Post-impact fire ensued.
The helicopter had departed about one hour after moon set and one hour before morning civil twilight. The pilot had flown a similar operation the previous morning. The client requested the flight the evening before, and the operator discussed lighting conditions with the pilot at 0500, reporting clear and starry conditions at the base. The pilot was advised to use discretion regarding departure timing.
Investigation Findings
The investigation determined that the pilot almost certainly encountered cloud near Lawrence and likely attempted to manoeuvre around it. With increasing cloud cover and little terrestrial light over the Lammerlaw Range, the pilot very likely lost their clearly defined horizon. The helicopter continued climbing for nearly three minutes before the pilot very likely became disorientated. This disorientation very likely resulted in a high angle of bank turn, followed by a rapid descent consistent with spatial disorientation and loss of control.
The pilot held a restricted night rating and had met currency requirements, but had not logged instrument flying practice in about nine years. It was considered very unlikely that the pilot was proficient in flight with sole reference to instruments at the time.
Safety Issues and Recommendations
Two safety issues were identified by the Transport Accident Investigation Commission. First, the rules and guidance for night Visual Flight Rules (VFR) are ambiguous, potentially allowing pilots to fly beyond permitted distances and encounter conditions outside their capabilities. Second, current rules for instrument currency for night VFR do not adequately mitigate the risk of inadvertent flight into conditions where the horizon is lost. The Commission made two recommendations to the Director of Civil Aviation to address these issues.
Additional Information
The helicopter's Emergency Locator Transmitter did not activate. The search was aided by ADS-B data and the aircraft's tracking system. The wreckage was located at 2434 feet AMSL, just below the cloud base. The pilot had logged approximately 4230 total flight hours, including about 1200 on the AS350 type, and 63 hours of night flying.