A methamphetamine-affected ute driver who smashed head-on into a truck, causing it to crash off the road and burst into flames, has admitted causing the death of the truck's driver.

Karl Dee McQuillan was arraigned and pleaded guilty to charges of driving under the influence of a drug causing death, possession of methamphetamine, possession of MDMA, and unlawful possession of ammunition and explosives when he appeared in the Hamilton District Court on Thursday.

As the agreed summary of facts in the case reveals, the truck driver, Craig Searle, was driving a heavy truck and trailer transporting farm machinery northward on State Highway 27, through the Waikato settlement of Waharoa, about 6.30am on Friday, June 26, 2020.

He was doing about 65kph and safely travelling in the correct lane.

Coming the other way was McQuillan, who was behind the wheel of a Toyota Hilux, doing about 68kph.

For reasons that are unclear, McQuillan failed to negotiate a bend in the road and crossed the centre line, moving entirely into the northbound lane and directly in the path of Searle's truck.

Searle had no time to avoid the smash and, as the summary puts it, the left front of the truck collided heavily with the left front of the ute.

Searle lost control and the truck and trailer smashed through the roadside safety barrier, and plummeted down over a railway overbridge.

The front section of the truck came down onto the railway line where it caught fire.

Searle died at the scene.

McQuillan suffered injuries to his abdomen and head and was transported to Waikato Hospital by rescue helicopter, where a blood sample taken seven hours later was and found to contain 0.43 milligrams of methamphetamine per litre of blood.

A few days later the police obtained a search warrant to investigate what was inside McQuillan's vehicle.

Inside, they found three large two-litre containers with what appeared to be the remnants of a large amount of white crystal material and a small snap-lock back containing 0.9 grams of crystal.

It was methamphetamine.

Also located in the ute, besides McQuillan's prescription medicine and the meth, was another snaplock bag containing 1.5 grams of MDMA.

They also found a 'pelican” box containing 49 rounds of 20-gauge ammunition and a round of .308 ammunition.

McQuillan's home in Taumata Road, near Omanawa, was also searched. Numerous drug utensils, 93 rounds of shotgun ammunition, and a .22 round were found there.

When spoken to by the police, McQuillan had no explanation for either his actions that day, or the items that the police had found.

He was remanded on bail by Judge Philip Crayton to next appear for sentencing on July 27.

-Stuff/Mike Mather.