The pilot killed alongside six tourists in a scenic helicopter flight at Fox Glacier was not adequately trained and may have misjudged how high above the terrain he was, an investigation has found.
The helicopter was found to have flown straight into the glacier, and throughout the flight the overall weight of the craft almost certainly exceeded the maximum permitted weight.
The investigation revealed the helicopter struck the glacier surface with a "high forward speed and a high rate of descent, with the engine delivering power".
The Transport Accident Investigation Commission (TAIC) today published its final report on the November 2015 crash, saying the operator's pilot training system did not fully prepare the pilot for his role.
Queenstown pilot Mitch Gameren, 28, and six tourists were killed when the Alpine Adventures' AS350 Squirrel helicopter he was flying on a scenic trip plunged into a deep crevasse in the glacier on November 21, 2015.
The tourists were Australians Sovannmony Leang, 27, and Josephine Gibson, 29, as well as Cynthia Charlton, 70, husband Nigel Charlton, 66, Andrew Virco, 50, and his partner Katharine Walker, 51, all from the UK.
TAIC found it was unlikely any mechanical failure was a factor in the crash. Although not all of the wreckage was recovered, an examination of what they did find revealed no pre-existing failure.
It did find the weather conditions in the area were particularly likely to have been below the minimum criteria required by civil aviation rules.
The investigation also revealed the company had been allowed to continue operating with little or no intervention from the Civil Aviation Authority (CAA), despite it having identified significant issues.
"The Civil Aviation Authority (CAA) identified significant non-compliances with the operator's training system and with managerial oversight prior to the accident," TAIC chief commissioner Jane Meares said.
"However, the CAA did not intervene and the operator was allowed to continue providing helicopter air operations."
On Monday, the CAA announced at a press conference they had overhauled the way they trained and recruited helicopter operations inspectors after discovering their officers were taking a "soft approach" to the job and had been misled by operators.
Today, Meares said the CAA inspectors had "overlooked" and failed to raise findings on "significant non-compliances with civil aviation rules" in the case of the operator of the Fox Glacier accident helicopter.
"The Commission is concerned that there could be a wider safety issue whereby other civil aviation operators during the same period could have significant non-compliances that were not identified or not resolved," she said.
After discovering this, TAIC recommended the CAA independently review its past surveillance activities, which it did.
The report into the crash said the helicopter was expected to take a 20-minute flight that day. The weather was "cloudy and changeable".
It was reported overdue at 10.15am and a subsequent search revealed its wreckage on the glacier just below Chancellor Shelf.
The weather conditions were "unsuitable" for conducting a scenic flight, the report said.
"It is very likely that when the helicopter took off from Chancellor Shelf and descended down the valley, the pilot's perception of the helicopter's height above the terrain was affected," it said.
Factors such as cloud, precipitation, flat light conditions, and condensation on the front windscreen could have affected this.
"The Commission found that the pilot had not been properly trained and did not have the appropriate level of experience expected under the operator's categorisation scheme for a senior pilot in this type of operation.
"The operator's system for training its pilots was ill-defined and did not comply fully with the civil aviation rules."
Other findings included that the tail rotor servo had exceeded the maximum flight hours permitted before overhaul, though that was unlikely to have contributed to the crash.
"The operator's training system did not have sufficient oversight by the designated senior persons. This was a factor that allowed the pilot to be assigned roles and responsibilities without the proper training and experience."
The Commission opens an inquiry when it believes the circumstances of an accident or incident have - or are likely to have - significant implications for transport safety, or when the inquiry may allow the Commission to make findings or recommendations to improve transport safety.
After the crash, CAA suspended the Air Operating Certificate (AOC) of Alpine Adventures' managing director and owner James Patrick Scott, grounding his 15-strong helicopter fleet.
In 2016, the CAA charged Scott and quality assurance manager Barry Waterland's company, Aviation Manual Development (2009) Ltd under the Health and Safety in Employment Act legislation.
Scott and Aviation Manual Development pleaded guilty to failing to take all practicable steps to ensure no action or inaction of any employee while at work harmed any other person. The maximum penalty is a $250,000 fine.
They pleaded guilty on the basis their failings had not caused the crash.
Scott has made voluntary reparation payments of $125,000 to each of the seven families, totalling $875,000.
He was also fined $64,000 by the court.