An inquest has been told a Perth police officer did not hear an order to abort a high speed chase moments before the car being pursued crashed, killing an innocent couple and severely injuring their son.

Key points: The chase began when a stolen Ford Falcon was spotted by two undercover officers

The chase began when a stolen Ford Falcon was spotted by two undercover officers They were ordered to abort the pursuit, but claimed they didn't hear the order

They were ordered to abort the pursuit, but claimed they didn't hear the order A couple were killed in the resulting crash, and their son left in a coma

The inquest is being held into the deaths of Glenys and Kevin Forbes, who were driving in a car with their 25-year-old son Michael on Warwick Road in September 2016.

Their car had just emerged from a stop sign when they were struck by a Ford Falcon that had been travelling at between 155 and 170 kilometres per hour.

Their car spun a number of times and landed more than 30 metres away from where the collision occurred.

Mrs Forbes, 60, died at the scene. Her husband, 66, died a short time later in hospital.

The car Glenys and Kevin Forbes were driving landed more than 30 metres from where it was hit. ( Supplied )

Their son was in a coma for days after the crash and awoke to be told about the deaths of his parents.

An unlicensed teenager who was driving the Ford Falcon that was being chased by police was charged with manslaughter and ultimately sentenced to eight years in juvenile detention.

Spotlight on police handling of chase

A coronial inquest is investigating whether police actions in pursing the car contributed to the deaths of Mr and Mrs Forbes.

Senior Constable James Armstrong was driving the unmarked police car with his colleague, Constable Luke Jackson, in the passenger seat.

Senior Constable Armstrong told the inquest the pair attempted to pull over the Falcon after a check on its licence plates revealed the registered driver was older than the person behind the wheel.

The Falcon failed to stop and as the police gave chase it started to gain speed.

The Ford Falcon smashed into the family's car after it emerged from a stop sign. ( ABC News )

The inquest was told a police duty inspector ordered the officers to abort the pursuit, but Senior Constable Armstrong told the court he did not hear that instruction or a later directive from the radio control operator to downgrade.

"Luke and I were talking about what was going on, there was a lot of noise, a lot going on," Senior Constable Armstrong said.

"I didn't hear it. I hadn't realised we were going so fast."

He told the court he slowed down moments before the crash happened.

The police officers witnessed the crash between the Falcon and the Forbes' family car.

Death badly affected officers

Senior Constable Armstrong said he had been involved in other pursuits that ended in serious crashes both before and after the incident.

But he said this case had a significant impact on him and, with the benefit of hindsight, he would never have begun pursuing the Falcon in the first place.

Senior Constable James Armstrong said he didn't hear the order to abort the pursuit. ( ABC News )

"I had a lot of counselling after this," he said.

"As it turned out it was some kid with a silly warrant.

"If I'd known two people were going to die I'd never [have] chased it at all."

Mr Forbes's brother and the couple's two children were in court for the hearing.

At the conclusion of the inquest, Coroner Barry King addressed Mr and Mrs Forbes's family members, who were sitting in court, telling them that he did not plan to make any adverse findings against the individual officers involved.

"The police officers were trying to do their job," he said.

"I can't condemn them for doing what they did. Their decision to engage and keep engaging was justified.

"But for all the things that can happen to a family, this is possibly the worst."

Family does not blame police

Outside court, Mr and Mrs Forbes's daughter Alison said she also did not blame the officers for the crash that killed her parents.

"I don't think it's an individual police officer problem," she said.

"I think it's an issue that is more complex than two people involved.

"After today's inquest, if there's findings that support changes to police pursuit policy then that's something that we'd support to avoid something like this happening again down the track."