A senior air force officer warned his superiors that helicopter crews were risking their lives five months before an Iroquois crashed in cloud near Wellington, killing three men.
The warnings came from an officer who trained the men, approved the fatal flight and has now emerged as a whistleblower who tried to warn about the problems leading to the Anzac Day 2010 tragedy.
Defence Minister Jonathan Coleman says an independent inquiry into the crash will not look for someone to blame, but will be to ensure that recommendations for change had been acted on.
Dr Coleman said the Military Police had completed their work on the case, and their findings were now with Crown Law to consider whether any further charges would be laid.
Dr Coleman said he will now set up an independent inquiry to assess how the 27 recommendations made by a court of inquiry into the crash had been acted on.
"I am confident they have been, but there's high public interest in the case and I think it's fair enough that the public get that reassurance."
He said the Chief of the Defence Force had assured him that good practice was being followed, but he believed it was worth getting an objective assessment of that.
It was yet to be decided who would lead the inquiry, but he expected to discuss that with officials this week and hoped to set up the inquiry with some speed.
The crash killed the pilot, Flight Lieutenant Hayden Madsen, 33, co-pilot Flying Officer Daniel Gregory, 28, and crewman Corporal Ben Carson, 25.
A court of inquiry report into the accident, released last December, castigated the air force's safety record.
It said "risk taking" was endemic and "the 'can do' culture ... can result in an increased likelihood to misperceive risk, push limits and take risky actions".
But the Herald has learned the issues about the culture at 3 Squadron were raised in November 2009 by then Squadron Leader Rob Stockley.
He told bosses in an email that safety rules were being broken by Iroquois crews from Ohakea air base.
Crews were flying too low without approval, taking risks with bad weather and a culture of risk-taking had developed which could have fatal consequences.
He used words echoed in the inquiry report, saying the squadron's "can do" attitude could kill.
"How long do we let this line of thinking develop before someone screws up and gets charged or, worse, crashes? ... Can do, can kill."
The Herald has confirmed with Mr Stockley that he sent the email. He said he was haunted by it because his warnings had not been heeded.
"I wish I had done more," he said.
Electronic signatures show it was sent to 3 Squadron's leader, Wing Commander Russell Mardon, and eight other senior officers.
Mr Mardon has left the air force and now works overseas.
Mr Stockley resigned from the air force before the crash and left about eight months after it. He was acting commander on the day of the crash.
In August 2011, he was charged with failing to comply with written orders by approving the Anzac Day flight. The air force said the right person to approve the flight was Mr Mardon, who was on leave at the time.
A military court found him guilty, but he appealed, and a higher court found that he did have the authority to approve the flight and the air force's charges were based on an inaccurate understanding of its own orders.
Mr Stockley said he believed senior air force staff were looking for a "scapegoat" and was concerned those in the other helicopters in the Anzac Day flight might face charges.
In a statement, RNZAF chief Air Vice-Marshall Peter Stockwell said there had been "significant work" to "help ensure safer flying operations", including development of a new safety monitoring system.
He said changes included "intensive scrutiny" of the culture at 3 Squadron with "a stronger focus on awareness ... and adherence to orders, instructions and procedures".