A coroner has found seven members of the same family died when their van crashed head on into a truck near Picton last year because the driver was fatigued.
The van carrying nine people crashed after crossing the centre line of State Highway 1 on 19 June 2022.
Paul Brown, his wife Diseree Lagud, Mark John Lagud,15, Flordeliza Dolar, 19, Divina Dolar, 47, Li-Hsuan Chen, and Mika Ella Chen Clariman, aged six months, died in the crash.
Coroner Alison Mills found the driver, Paul Brown, had been experiencing microsleep, when a person drifts in and out of sleep without knowing it.
"These naps can last between three and five seconds and are the main cause of fatigue-related crashes where the driver runs off the road.
"If this happens while driving it can cost you and your loved ones their lives."
She concluded Brown had no more than three hours and 50 minutes sleep in the 24 hours before the accident.
Although it was possible he may have had slightly more sleep between Timaru and Rolleston Mills, she said she accepted it would have been minimal and would not have been meaningful deep sleep.
The van's break filaments showed no signs of hot shock, indicating they were not illuminated and that the brakes were not used during the crash.
Nor was there any physical evidence Brown reacted or made an effort to avoid colliding with the oncoming truck.
Brown and his wife Diseree Lagud, together with seven members of their extended family had planned the trip to attend Brown's aunt's funeral in Gore, which was held the day before the fatal crash, and to visit his mother in Dunedin.
It was meant to be a chance to show family visiting from the Philippines parts of the South Island.
Brown was described as a "very safe driver" who always kept to the left because it was safer, was not known to drive fast and always told passengers to wear their seat belts, the report said.
On the morning of the fatal crash, Brown woke his family at 2.30am and told them to get in the van. Brown had had no sleep because he was talking to his friend.
His wife's 26-year-old son Pedro Lagud Clariman commented he thought they were going to stay and sleep at the friend's house until about 5am, but Brown wanted to get to Picton early and have breakfast before catching the midday ferry.
Brown's friend confirmed in the Coroner's report that he offered the family a chance to stay despite not having enough beds for everyone. He and Brown spent the night chatting as they had not seen each other for four years.
He provided hot drinks and food but no alcohol.
He had no concerns about the family's choice to continue driving after they left.
The family left Rolleston at around 3am with Pedro in the driver's seat for almost four hours, though he pulled over for a 15-minute break because he felt sleepy.
Brown took over the driving.
Richard Thompson, the driver of the truck and trailer unit, said as he came around the bend on State Highway 1 he saw a van coming towards him which kept coming across the centre line.
He said he tried to avoid the van by hugging the left side of the road and applying the brakes but was unable to avoid the collision.
He lost steering of the truck as the wheel locked up while he was pulling hard on it.
The truck ended up in a ditch on the opposite side of the road and rolled over.
The crash knocked the van backwards about 20 metres. It was extensively damaged, including the driver's side being mangled and pushed back and over to the right passengers side.
At the time of the accident, Pedro remembers dozing and listening to the noise of the van. He could not hear anything then suddenly felt and heard an impact.
He opened his eyes and felt his legs and face hurting.
Pedro's six-month-old daughter Mika was not restrained properly in her car seat. The baby capsule was found lodged against the pillar by the driver's seat and was severely damaged.
Several members of the public including two nurses arrived at the scene and attempted to provide first aid and assess injuries.
When Pedro managed to get out of the van he was in extreme shock.
Coroner Alison Mills said the accident was avoidable and a reminder of the real risks of driving when tired or fatigued.
She encouraged drivers to be aware of the signs of fatigue, plan journeys that did not involve travelling excessive distances and make sure they got sufficient sleep.
RNZ