Pilot, 26, fined for driving dangerously before motorcyclist's fatal Mandurah crash

A qualified pilot who chased a motorcycle rider at high speeds, before the motorcyclist crashed and died, has admitted he acted "in the heat of the moment".

On Tuesday, Loris Livieri, 26, pleaded guilty in the Mandurah Magistrates Court to dangerous driving, which had been downgraded from reckless. Investigators determined he was not responsible for the fatal accident.

Police prosecutor Emma Houghton said Livieri was travelling west on Pinjarra Road towards the Mary Street and Old Coast Road roundabout in Halls Head about 8.30pm on March 16, 2019.

The lane merged into one due to road closures over the Crab Fest weekend.

Senior Constable Houghton said as the lanes were merging, a rider of a black Harley Davidson motorcycle collided with the left of Livieri's car, before speeding off along Old Coast Road.

The motorcycle rider was evading police at the time, which Livieri was unaware of, she said.

Senior Constable Houghton said the motorcycle rider had been travelling at 162 km/h for about 1.2 km, in a 50 km zone.

She said Livieri followed the rider along Old Coast Road in a 60 km zone at speeds between 129 km/h and 134 km/h.

Senior Constable Houghton said the motorcycle rider failed to negotiate a roundabout and crashed.

The 29-year-old Dawesville man died in hospital as a result of his injuries.

She said major crash investigators determined Livieri had not played a part in the man's death.

Livieri's lawyer Shirley Casey said her client had followed the motorcycle rider to obtain his registration details.

She said he had acted "in the heat of the moment" and the incident resulted in a "tragic outcome for all concerned".

Ms Casey said Livieri travelled to Perth from New South Wales to follow his career as a pilot and hoped to eventually work for Qantas.

He did not have a WA criminal record but had received minor driving infringements in NSW.

She said Livieri had supportive parents who travelled from NSW to attend the court hearing.

Ms Casey said Livieri would be moving back over east.

Livieri was fined $1500.

An application for a spent conviction was denied by Magistrate Anne Longden.

"This was an ill-fated decision on your part," she said.