At some point the employee noticed the three children getting closer to the mower. He waved at them to get out of the way and tooted the tractor's horn to warn them.
On the mower's eighth run across the park, the victim stopped running behind the mower and sat down while the other two children continued to chase the mower. On the next run, the mower passed Uetaha sitting on the ground.
During the tenth run, Uetaha was running at a diagonal angle towards the tractor when he was struck and run over by the right-hand side of the mower unit, suffering fatal injuries, Mr Stewart said.
"Children are particularly at risk when public areas like parks are being mowed.
"While the Hastings District Council did have an informal system of stopping the mower and not starting it again until the member of the public had moved on, this process should have been formalised and documented in the safe operating procedures for the tractor mower," he said.
"The guidance should also have been clearly articulated to all staff so that they knew how to use the tractor mowers safely. Those simple steps could have made all the difference to the victim and his family."
Last year, Ross David Pollock, the driver of the tractor, pleaded guilty to driving a vehicle dangerously.
He was sentenced on July 11 to six months' home detention, 100 hours' community work, disqualified from driving for three years and ordered to pay $5000 reparation.
The senior driver - who and been with the council for 13 years - expressed his regret and said he was "full of sadness" during his sentencing, which came a month after he retired from council duties.
Later, Pollock, who had no previous convictions and a clean driving record, successfully appealed the period of driving disqualification imposed.
The three years' disqualification was quashed and a period of 18 months was imposed in lieu.
The council said in February it had reviewed its safe operating procedures for all mowing operators and improved the training and supervision of drivers in the wake of the incident.