Dwayne Albert Cashman sentenced for 2016 fatal crash at Perth

Dwayne Cashman.

Dwayne Cashman.

An intoxicated veteran who caused a fatal crash on the Midland Highway has been sentenced to three and a half years' jail. 

Dwayne Albert Cashman, 46, was originally charged with manslaughter, but he pleaded guilty to causing death by dangerous driving and four counts of causing grievous bodily harm by dangerous driving. 

In December 2016, Cashman woke up about 6am after drinking at a friend's house until 2am and having less than four hours sleep.  

He had breakfast and then proceeded to drive home.

The Wynyard man drove at speeds up to 160 km/h on the Midland Highway, reaching the Woolmers Lane turn off about 8.15am. 

Despite driving at such excessive speeds, Cashman took his eyes off the road to change a CD.

His wheels left the road and he drove in the gravel for more than 39 metres before trying to correct the steering and return to the road. 

He was driving at 148 km/h when he lost control of the car, crashing into a Kia travelling in the opposite direction. 

The Kia was travelling at 99 km/h and Cashman's car at 140 km/h hour when they collided.

Cashman returned a blood alcohol reading of 0.069 about two hours after the crash, with a forensic specialist determining his reading would've been 0.086 at the time of the collision. 

David Smith, the driver of the Kia, had his wife and four children in the car. 

Mr Smith, 53, died at the scene. His wife and three of his children were seriously injured in the crash. 

During sentencing on Thursday, Justice Robert Pearce said it was a tragic case from every perspective.

"A man of otherwise good character, who has provided service to his country and the community, finds himself in prison," Justice Pearce said.

The combination of speed, alcohol, fatigue and inattention was a "disaster waiting to happen", Justice Pearce said. 

Justice Pearce noted Cashman's service to his country through his years in the army and volunteer work in support programs. 

Cashman developed post traumatic stress disorder after serving in Rwanda in the '90s. He took some leave but returned to the army, serving in Timor before being medically discharged in 2005. 

"Since leaving the army he has given service to the community by holding a number of positions in organisations providing support for ex-service personnel," Justice Pearce said.

Cashman's licence was cancelled and he was disqualified from driving for four years after his release. He will be eligible for parole in two years. 

Cashman waved to family members in the courtroom, with a woman shouting "love you" to him.

Mr Smith's family were also in court, with one member saying they were "relieved it's finally over".