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New Zealand’s accident investigation body is recommending anomalies in Civil Aviation rules be addressed as a result of its findings into a fatal helicopter crash near Lawrence in 2021.
The Transport Accident Investigation Commission (Taic) released its final report yesterday on the crash, which killed Milton pilot Dan Harrison.
Mr Harrison, 36, was flying an AS350 Squirrel from Milton to Alexandra to carry out frost protection work early in the morning of September 16 in 2021 when it went missing.
The report, which found Mr Harrison probably became disoriented while flying in darkness and cloud, led to the Taic recommending in September that the Civil Aviation Authority (CAA) address a lack of requirements for pilots to practise instrument-only flying, and resolve "ambiguity" in its night Visual Flight Rules.
Mr Harrison departed Milton about 5.15am, with no moon, in the darkest part of the night.
He almost certainly encountered increasing cloud, and "very likely" lost a clearly-defined horizon soon after passing Lawrence.
A pilot in such a situation needed to immediately switch to instrument-only flying to maintain situational awareness and control of the aircraft, the report said.
Flight data showed the helicopter made a tight descending right-hand turn, then a left-hand spiral dive that ended in a near vertical nose-down high-speed impact with the ground.
Mr Harrison had about 4200 hours’ flying experience since gaining his commercial helicopter pilot licence in 2008.
The report said he held a restricted night rating, which allowed him to fly within 25 nautical miles of his aircraft’s departure point, but not to fly cross-country.
He had not logged instrument-only flying practise in the nine years before the accident, so was unlikely to be proficient in the skill.
In a media statement, the Taic chief investigator of accidents Naveen Kozhuppakalam said it was an "anomaly" that pilots with a restricted night rating were not required to practise regularly.
If a pilot lost sight of visual references, such as on a dark night in thickening cloud, there was more risk of them being unable to rely solely on their instruments, making them more vulnerable to disorientation and losing control of their aircraft, Mr Kozhuppakalam said.
"That’s very likely what happened in this accident."
The night Visual Flight Rules were intended to keep pilots with a restricted night rating within 25 nautical miles of their departure point, but could be interpreted to allow pilots to fly from one 25-mile zone to the next and so on, across country.
"This is much further than intended; it puts pilots at risk of encountering night flying conditions outside their capabilities."
In response to the recommendations, the CAA has convened an industry helicopter working group to consider the issues they raise.
The helicopter’s operator, Alister John Lister, and his company Lister Helicopters Ltd, face a variety of charges before the Dunedin District Court in relation to the crash.
There have been repeated appearances without significant progress, but at the last call, a judge stressed pleas would be expected next month.