The pilot of a tourism helicopter that crashed in New Zealand's South Island, killing all seven people on board, wasn't properly trained and the country's aviation watchdog failed to intervene despite red flags, investigators have found.
Australians Josephine Gibson, 29 and Sovannmony Leang, 27, died along with four British tourists and 28-year-old pilot Mitchell Paul Gameren when a sight-seeing chopper plunged into a Fox Glacier crevasse on November 21, 2015.
New Zealand's Transport Accident Investigation Commission on Thursday released its report into the disaster, finding the Eurocopter AS350 Squirrel helicopter - operated by tourism company Alpine Adventures - had flown out in poor weather, despite the cancellation of other flights that day.
It said the pilot's sense of height over the terrain was likely affected by cloud, rain, flat light or windscreen condensation.
The report concluded the helicopter descended quickly and struck the glacier at "high forward speed", with the engine still going - although the lack of an on-board recorder made a definitive account impossible.
"The pilot had not been properly trained and did not have the appropriate level of experience expected," the commission said.
It said the Civil Aviation Authority (CAA), New Zealand's flight regulator, had found major problems with the operator's training systems that "warranted intervention long before this accident occurred."
"The operator had been allowed to continue providing helicopter air operations with little or no intervention from the Civil Aviation Authority, in spite of the authority having identified significant non-compliances with the operator's training system and managerial oversight," the report said.
Gameren had about 1800 hours of flight experience. Mechanical failure was ruled unlikely.
The CAA pre-empted the report by this week admitting oversight should have been more rigorous, and that not enough pressure had been put on the operator to improve safety.
In a statement on Thursday, it said the report reinforced the need for ongoing efforts to improve its performance, and that changes had started as far back as 2013.
"The CAA of today is a much more effective regulator than it was in 2012," CAA director Graeme Harris said.
Josephine Gibson's father, Charles, earlier told Radio NZ the oversight system had been "completely rotten" and the CAA needed to be held accountable.
"There's seven dead, the CAA has failed in their due diligence," he said.
This month, Queenstown-based Alpine Adventure's then-owner, James Patrick Scott, was fined $NZ64,000 ($A60,438) after admitting to breaches of health and safety laws. He also made voluntary reparations of $NZ125,000 to each of the families of the seven killed.
The other victims were British tourists Nigel Charlton, 66, Cynthia Charlton, 70, Andrew Virco, 50, and Katharine Walker, 51.
Australian Associated Press