Warren Carter was killed last year in a collision with a Defence Force truck.

The Defence Force will re-examine a fatal but controversial crash involving a seven-tonne Unimog vehicle.

Defence Minister Ron Mark on Wednesday confirmed the Defence Force would re-open its Court of Inquiry into the fatal crash in Manawatū in August 2017.

To a mate of the 71-year-old Wairarapa victim, the move is not enough. What Barry O'Donnell wants is a full, public investigation that looks wider than police looked and has more transparency than the Defence Force's examination.

SUPPLIED The scene of the crash.

Only that, he argued, would show who, or what, was really responsible for the death of his mate Warren Carter, 71, who died when the Unimog crashed into his car on a quiet intersection near Ashhurst, east of Palmerston North.

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Private Dayne Pennington, who had held a normal car licence for only five weeks, was the Unimog driver. After a day's training, it was his first time on an open road in the truck.

KEVIN STENT/STUFF Minister of Defence Ron Mark has confirmed the Defence Force will reopen its court of inquiry into the Wairarapa Unimog death.

A highly-detailed police crash report concluded: "The actions of Pennington, applying the incorrect foot pedals, must be considered as the prime causative factor in this crash" while "generally drivers will use the right foot for braking and accelerating".

The trainee, 24, pleaded guilty to careless driving causing death and was granted a discharge without conviction in Palmerston North District Court. He also faced an army Court of Inquiry.

O'Donnell argued the police investigation only looked at the death from a traffic perspective and ignored the wider factors that could potentially exonerate the trainee driver.

He believed WorkSafe should investigate with a public ruling - as opposed to what he saw as a hasty determination. That investigation could look at the wider issues rather than just the trainee's actions.

He was "not really in a position to be sad or glad" about the Defence Force reopening its inquiry as it was not clear if it would look at new evidence nor whether the same people would make a ruling.

Furthermore, the Court of Inquiry's rulings, and proceedings, were usually kept private and only usually for internal use.

"There needs to be a full public inquiry. Mrs Carter's [Warren Carter's wife] view is, as I see it, the same."

Apart from saying the foot pedal technique was not used, the Defence Force has refused to comment on the case since the Court of Inquiry was concluded.

Mark said he had always pledged to look into the matter and on Wednesday said he had gone back to the Defence Force with questions, for which he had some answers but still needed a couple more.

As a result of those questions the Defence Force had decided to reopen the Court of Inquiry.

Mark said he had made no predeterminations about what it would find though there were facts - including some from the police serious crash report and a WorkSafe determination - that were undeniable.

He understood the Court of Inquiry process had already started.