Kenneth Wolnak was planning on travelling to Kaiteriteri with his wife to explore Abel Tasman National Park, but he turned the wrong way and never made it.

After leaving his accommodation in Westdale Rd, between Nelson and Motueka, about 10.25am on February 27, the American heart surgeon on holiday in New Zealand, turned left onto State Highway 60.

He drove about two kilometres in the Toyota SUV he had hired in Christchurch when he arrived in the country in mid-February before realising he should have turned right.

MARTIN DE RUYTER/FAIRFAX NZ The crumpled wrecks of the Isuzu truck and caravan towed by a Toyota Prado. The drivers of both vehicles died at the scene.

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So he pulled over about 300 metres south of Maisey Rd.

The 63-year-old then made the fatal mistake of attempting to perform a U-turn on the busy Coastal Highway.

KELSI HARDIMAN Steve Jayes, left, was the driver of the Isuzu truck and died at the scene of the crash. Jayes is pictured with his sons Cassius and Lennox, and his partner Monique Hardiman.

Wolnak pleaded guilty in the Nelson District Court on Tuesday to two charges of careless use of a motor vehicle causing death and four charges of careless use causing injury.

THE CRASH

The court heard that as Wolnak pulled back out, an Isuzu flat-deck truck carrying about 6.5 tonnes of scaffolding was heading north at about 90-100kmh.

The driver of the truck, 41-year-old Steve Jayes, rounded a slight bend in the road and was confronted by Wolnak's vehicle in his path, about 50m ahead of him.

Jayes attempted to swerve but crashed head-on into the passenger side of Wolnak's vehicle.

Wolnak's vehicle spun around, stopping in the northbound lane.

The truck crossed the centreline into the path of southbound traffic.

Kevin Whitburn, 69, and his wife Janet, of Christchurch were heading south in their Toyota Prado, towing a caravan, after holidaying in nearby Mapua.

They were travelling at about 80-90kmh when they crashed into the Isuzu truck, causing it to spin clockwise and spill the scaffolding across the road.

The momentum of the truck caused it to crash into the caravan.

The caravan was "decimated" with parts strewn across the road, the police summary of facts said.

Jayes, a father of two boys, and Whitburn, in his first year of retirement, both died at the scene of blunt force trauma.

THE INJURIES

Wolnak's wife, who was in the front passenger seat of their vehicle, suffered seven rib fractures, compression of the lung, as well as sacrum, pelvis and jaw factures. She has only recently been discharged from hospital.

The middle-seat passenger of the Isuzu truck, a 19-year-old Nelson man, suffered bleeding around his right kidney, a broken nose, fractured eye socket, gouging to forearms, cuts to his calves, bruising to his thigh and a sore back.

The other passenger in the truck, a 28-year-old Nelson man, fractured his left leg and had cuts to his leg and elbow.

Both occupants of the truck were trapped inside the cab for about 40 minutes while members of the fire service worked to cut them free.

Janet Whitburn, 65, sustained a cut to her head that required stitches, tenderness to her torso and whiplash.

THE WRONG TURN

Wolnak told police that he had looked at a map of his accommodation before leaving his accommodation in the morning and was meant to travel to Kaiteriteri and visit Abel Tasman.

He said he can't remember anything of what happened after he turned left onto the highway.

Wolnak has been remanded at large. His sentencing has been scheduled for April 24.

Judge Bruce Davidson asked that restorative justice be explored with the victims.

Wolnak is a cardio thoracic surgeon based at Mercyhealth Medical in Janesville, Wisconsin.

Wisconsin-based website GazetteXtra reported Mercyhealth Medical director Dr Mark Goelzer as saying that Wolnak had worked there for 15 years and was an "excellent physician who is very well-liked by his patients, peers and the community".