Passengers of a minibus were worried about the driver's fast speed and that he was drifting off the road in the hours before he fatally crashed into a paddock.
Bruce Kenneth Slater, 77, is facing prison time for falling asleep and crashing a minibus in regional Victoria in May 2021, killing one woman and injuring three others.
He has pleaded guilty to dangerous driving causing death and dangerous driving causing injury, and faced the County Court in Melbourne by video link for a pre-sentence hearing on Monday.
Slater was driving a group of 10 people from a senior citizen's club in Gunbower, northern Victoria, on a silo art tour.
After leaving on the morning of May 20, several passengers expressed their concerns to Slater about his speed and attitude to driving, prosecutor Jonathon McCarthy told the court.
He said one person believed they saw Slater drive the minibus onto the gravelled side of the road about 10 times that morning,
After a lunch break in Benalla, another passenger became worried about Slater's driving as they felt him drive the vehicle onto gravel again.
"They could feel the stones under the bus and it was noisy," Mr McCarthy said that passenger reported.
When he was asked if he was alright to continue driving, he replied "no I'm alright", the prosecutor said.
About 2.30pm, Slater dozed off and the minibus rolled off the road, and hit a post and small tree.
Slater steered the vehicle hard to the right and caused it to travel across traffic to the other side of the road.
The minibus then went into a paddock and rolled three times.
Echuca woman Casey Spark, 40, died at the scene from injuries sustained in the crash.
Three others, including Ms Spark's mother Shirley, were taken to hospital with life-threatening injuries.
Mrs Spark, who suffered optical injuries as well as spine and rib fractures, said the grief of losing her daughter was "horrid".
"I have no tear ducts and physically can't cry, but I want to," she said, in a statement read to the court.
Slater, who is facing up to 10 years in jail for killing Ms Spark, had suffered from sleep apnoea since the mid-1990s, the court was told.
He required a machine to sleep, but prosecutors alleged it was not properly maintained and he was not using it before the crash.
"He hadn't been using CPAP machine daily because his nose gets blocked," Mr McCarthy said.
"He had used a CPAP machine daily since 1995, he would've been aware of the need to maintain his CPAP machine."
Slater's barrister William Blake said his client was not aware the machine was in need of maintenance.
"I estimate he'd been using his device diligently in the years prior to the crash," he said.
"I accept he may have been completely naive by believing the CPAP machine was functioning as it should be."
Mr Blake said Slater's medical issues, which include obesity, diabetes and a heart condition, would not be well managed behind bars and the stress of being in custody could lead to further deterioration.
He asked for Judge Peter Lauritsen to take this into account in deciding Slater's sentence.
"Deterioration and how this will be managed in custody justify a departure from the mandatory sentencing provisions," he said.
The plea hearing will continue on August 7.
