The Transport Accident Investigation Commission has called attention to the high rate of accidents involving New Zealand's most common light helicopter, the Robinson R22, and urged the Civil Aviation Authority to take action.
A report into a fatal helicopter crash near Wanaka released on Thursday criticises the lack of safety training for pilots using the aircraft.
Marcus Hoogvliet, 21, and his 32-year-old instructor Graham Stott died when a Robinson R22 owned by Wanaka Helicopters crashed on 27 April 2011 near Mt Aspiring during a training flight.
The commission's report said the helicopter broke up mid-flight. It said the crash may have been caused by extreme turbulence, the main rotor speed being allowed to drop too much, or the pilots making abrupt movements.
In a statement on Thursday, the family of Mr Hoogvliet said the report confirms what they knew early on - that the crash involved an extreme wind event overwhelmed the helicopter.
The commission found that the Robinson R22 can fail at high altitudes in some circumstances and called for more safety training for pilots who may not be aware of the aircraft's limitations.
Chief investigator Tim Burfoot told Radio New Zealand's Checkpoint programme on Thursday that a Robinson R22 helicopter break-up during flight has occurred every 18 months since 2002.
"We've done several inquiries before that have involved Robinson helicopter in-flight break-ups, and it was just when we sort of noticed that trend, and then this one happened, we said we'd better take a deeper look and see what sort of pattern is happening here."
Mr Burfoot said the Civil Aviation Authority scrapped extra safety training in 1998.
"The arrangement between certifying these aircraft in New Zealand relies a lot on the certification requirement in the country of manufacture. So those requirements in the country of manufacture are then introduced into the New Zealand system. Somewhere along the line they've been diluted somewhat, and we're not quite sure how that's happened."
Mr Burfoot urged the Civil Aviation Authority to step in to prevent more light helicopter crashes. He said the danger of flying R22s at high altitudes and in turbulent conditions needs to be explained more clearly to pilots.
In a statement, the Civil Aviation Authority said on Thursday it accepts the commission's recommendations and would work to put them in place. It would review its emphasis on helicopter safety awareness and change regulations where needed to improve safety.
About 350 Robinson R22s are currently in use throughout New Zealand.