Not all of the wreckage of the helicopter at the Fox Glacier site could be recovered, because of the remote and dangerous landscape. Photo / Supplied
Not all of the wreckage of the helicopter at the Fox Glacier site could be recovered, because of the remote and dangerous landscape. Photo / Supplied
The long-awaited report into what caused a horror helicopter crash in the Fox Glacier and killed seven people was released on Thursday, making it one of the longest investigations into an air crash in New Zealand. What goes into these investigations and why does it take so long?
It's beenthree and a half years since the Alpine Adventures' helicopter Mitch Gameren was flying plunged into a deep crevasse in the Fox Glacier, killing everyone on board.
The weather on the morning of November 21, 2015 was described as "unstable" and "unsuitable" for a scenic flight in the report released into the crash.
It's believed the weather conditions may have caused Gameren to misjudge the distance between the AS350 Squirrel and the terrain, sending him flying straight into the glacier just below Chancellor Shelf.
The investigation found the Queenstown pilot had not had adequate training for his role, and despite the Civil Aviation Authority identifying significant issues with the operator, there had been little or no intervention to make sure they were operating safely.
The Transport Accident Investigation Commission made the findings in its report which was released on Thursday.
Chief investigator of accidents Captain Tim Burfoot said the Fox Glacier investigation was one of the longest they had done. Most took an average of 12 to 18 months.
Investigators tried to get to the crash site as soon as possible, but a number of factors could delay that, Burfoot said.
In this case, the location was remote and "particularly challenging" to get to. It was dangerous as well.
"We might actually have to wait several days before we can even get there, and then when you get there you need to do all your risk assessments.
"The last thing we want to do is have an accident when we're investigating another accident."
TAIC employed experienced glacier guides to get them to the wreckage, and had them carry out the work under the investigators' direction.
Because of the challenging landscape, not all of the wreckage could be recovered.
Recovery in some cases can take weeks or months. For example, in cases where a craft has crashed into the sea, investigators may have to wait several weeks for a recovery vessel to arrive.
They must also take time to carry out their "site mapping".
"We have to record exactly how everything was found and then we need to make sure we've got everything."
Once what can be retrieved of the wreckage has been found, it is taken to a warehouse in Lower Hutt.
The examination
The initial inspection of the wreckage takes about a week - then the longest part begins.
The team take closer looks at any pieces of interest, and send bits away for expert analysis.
"We need to discount as many theories as we can to try to get to the cause. That can take months, even longer in this case," Burfoot said.
"They're trying to establish the state of the aircraft before it crashed, trying to find out was there anything mechanical that contributed to the accident."
Factors that can make an investigation harder include there being no witnesses, no survivors, and no recording boxes in the craft. All of those were factors in the Fox Glacier crash.
Overseas manufacturers may want to send their representatives over, who will also want to carry out their own inspections.
"That can add another month or two," he said.
At the same time they are gathering documentation, maintenance records, analysing the weather at the time, and talking to operators.
"If we start uncovering . . . what we feel are safety issues within the wider system . . . that adds a huge amount more, cause now we've got to go start gathering all that documentation and interview regulatory staff, everyone else involved."
Mitch Gameren, the pilot killed in the crash, was not trained enough for the role, investigators say. Photo / Supplied
Often they need to send away pieces of the wreckage for expert analysis.
That's where we might send a broken piece of metal to a metallurgist to have a look at it under the microscope to tell us whether it broke as a result of the accident. To engage an expert like that and have them do it, that's probably added a month on to the job," Burfoot said.
If pieces needed to be sent overseas to the manufacturers' testing facilities, that added months more to the investigation.
In the Fox Glacier case, all of this had to be done.
"The worst case scenario, that all happened with this one," Burfoot said.
Preparing the report
Once all the investigating groups have finished poring over the wreckage and documentation to figure out what happened, the draft report is written. That may take about a month.
It must then be peer-reviewed, before interested parties are given the opportunity to make submissions on it. They are allowed 60 days to respond to the draft report.
The report then goes before the commissioners, who consider the feedback and may invite submitters to clarify or re-analyse evidence.
Occasionally the changes made to a draft report at this stage are significant enough to go through the process again, and parties are given another period of time to read and submit on the report.
Once the finishing touches are done, the commissioners approve the report and it is ready to publish.
Police search and rescue staff, along with Aoraki-Mt Cook Alpine Cliff Rescue and Fox Glacier Alpine Cliff Rescue at the scene a few days after the crash. Photo / Supplied
On top of this, TAIC is working on about 30 investigations at any one time, and each air crash investigator will have about four cases on the go at once. They must try to keep each one moving at a similar pace.
The entire process can take anywhere between 12 months and several years.
