'Microsleep' could have caused fatal Paekakariki crash coroner finds

Te Rauoriwa Daphne Pomare, 79, died in the crash in October 2016.

An elderly woman who flew home to New Zealand earlier that day is believed to have had a "microsleep" behind the wheel before crashing head-on into another car in Paekakariki last year.

Te Rauoriwa Daphne Pomare, 79, died in Wellington Hospital after the crash, which happened on October 23, 2016.

Witnesses say Pomare was driving about 70km/h along State Highway 1 when her car suddenly veered to the right and collided with another vehicle, a coroner's report revealed.

"I saw probably the car was about 100m away and swerving in and out of the centre lane two or three times," driver Jessica Lemana told coroner Christopher Devonport.

"I started to slow down . . . I was braking and got to about 20km/h. I was screaming what do I do, what do I do. That's when I looked up and saw the red car swerve out into our lane, swerve back into her lane, then veer back into our lane right in front and whacked us."

A person driving behind Pomare said they did not see her car's brake lights go on at any time.

Pomare was taken to Wellington Hospital, where she died.

There was no post-mortem examination as Pomare's family objected to it on cultural grounds.

Constable Lisa Toseland told the coroner there were several indicators the crash was fatigue-related. There was no evidence of braking by Pomare after she swerved several times before crossing the centre line.

Pomare had travelled from Australia overnight, landing in Auckland at 6am and flying to Wellington at 8am. She collected her car just after 9am and began driving herself to Levin. The crash happened about 10.45am.

Toseland said Pomare's body clock would be set around 5.46am.

"Had she not slept prior to her flight or during the flights, it could be assumed that she had been awake 20-22 hours ."

Toseland said a microsleep was a brief, unintended loss of attention, such as a blank stare, head snapping, and prolonged eye closure.

"This can occur when a person is tired but trying to stay awake to perform a monotonous task like driving a car or watching a computer screen. They can last from a few seconds up to two minutes, and often the person is not aware that a microsleep has occurred.

"In fact, microsleeps often occur when a person's eyes are open."

During a microsleep, a person fails to respond to outside information, such as a curve in the road or a red signal light.

Toseland said warm conditions in the car could have contributed to Pomare relaxing.

Coroner Devonport said he considered on the balance of probabilities that Pomare was affected by fatigue and had a microsleep while driving, which caused the crash.