The teacher driving a group of Australian students may have fallen asleep at the wheel before their mini van collided with a milk tanker, a coroner's court has heard.
An inquest into the deaths of Andre Vogel, 36, and Gabriel Runge, 16, is underway in Rotorua today.
Two witness accounts, from Inspector Kevin Taylor and Australian teacher Patricia Jeffree, have been heard so far.
According to the account given by Mr Taylor, it has been deduced fatigue was a major factor in Mr Vogel crossing the centre line and hitting the milk tanker on State Highway 5 near Reporoa on November 28 last year.
Six other students from Queensland's Noosa Pengari Steiner School, as well as Ms Jeffree, were also injured in the crash.
