Key Points:

Driver inexperience was one of the main causes behind an army Unimog crash that killed three young soldiers, the Queenstown coroner has found.

In his finding released today, Alan Macalister said all three men died of misadventure, but the accident could have been avoided if the 17-year-old driver had been supervised.

Private David James Partington, 17, the driver, Private Ashley Patrick Goodwin, 19, and Private Shane Adrian Ohlen, 21, died when their Unimog crashed through a steel road barrier and plunged about 70m into the Kawerau River at Kawerau Gorge on February 23, 2005.

The men were taking part in a driver training exercise.

Mr Macalister said as the Unimog entered a narrow part of the gorge it was seen moving to the left of the road, hitting a barrier.

"It then moved back towards the centre of the road and then appeared to be over corrected, veer to the left where it crashed onto, along and then over the barrier with its left front and left rear wheels."

Mr Macalister said the Unimog travelled on for about another 45 metres before rolling down the steep side of the gorge for more than 70m into the Kawarau River.

A witness to the accident said at no time did the driver apply the brakes.

Pte Goodwin's body was found near the river, and the bodies of Pte Partington and Pte Ohlen were found 12 days later downstream in Lake Dunstan.

Mr Macalister found the particular section of road where the accident happened was known to have the effect of "gating" - where the road appears to be narrower than it actually is.

A roading safety expert consulted for the findings said it would be "natural for a young person driving a large truck, approaching this area, possibly faced with a vehicle coming towards him, to think there was not enough room and to move his vehicle to the left".

Mr Macalister said Pte Partington had a class two full licence, which qualified him to drive the Unimog unsupervised on the open road, even though he only had two months experience with driving that type of vehicle.

"I consider there was driver 'inadvertence'. That is David Partington 'inadvertently' drove against the Amcor barrier," the coroner said.

"This is not going so far to say there was driver 'error'. I do not consider it appropriate to make such a finding as in my view the cause of the accident was probably lack of supervision and/or experience -- not a lack of judgement by the driver who probably did not have the experience to make such a judgement."

Mr Macalister said supervison may have averted the crash by instructing the driver to brake.

In his report, Mr Macalister made a number of recommendations in relation to the incident. Among them were:

* Increased supervision for trainee drivers until they had been issued a Defence Driving Permit;

* Transit should look at widening roads to prevent the "gating" phenomenon -- especially in the Kawarau Gorge; and

* Heavy vehicle licences to be renewed every five years.