Alan Williams, the father of 16-year-old Hayley Williams who died on the ride. criticised the amount of the fine
A theme park has been fined £250,000 after a teenage girl died after plunging 100ft (30.5m) from a ride.
In 2004, Hayley Williams, 16, from Pontypool, Torfaen, died after falling from the Hydro Ride at Oakwood, Pembrokeshire.
A judge at Swansea Crown Court said there had been a "failure on a massive scale" with the potential for serious injuries to a large number of people.
Oakwood Leisure Ltd had admitted failing to ensure visitors' safety.
The court had heard staff had failed to ensure passengers were safely restrained on the high-speed ride.
There was the potential of very serious injuries to a large number of people
Mr Justice Lloyd-Jones
After the hearing, her father Alan read a statement and said the fine was "derisory".
His wife Beverley had walked out of court after the fine was announced.
"If it had been one billion pounds it would not be enough," he said.
"Oakwood have had a fine but we, family and friends, have had a life sentence - a lifetime left to face the loss of our beautiful and talented Hayley."
Judge Mr Justice Lloyd-Jones said: "This was a failure on a massive scale amounting to a grave breach of ensuring the public were not exposed to risks to their safety.
"There was the potential of very serious injuries to a large number of people.
"The heart of this matter lies in critical failures in the supervision and monitoring of staff carrying out their duty.
This is footage of the Hydro ride operating sometime after it first opened in 2002.
He said the CCTV footage showed it was "not an isolated incident", with the restraints for a large number of passengers not tested on the day of the incident.
"They fell far short of what they should have to ensure the safety of the public.
Sunday school teacher Hayley had been taken to Oakwood as a treat along with her sister Hannah by their parents Alan and Beverley in April 2004.
She died after falling from the rollercoaster, which had been advertised at the time as "Europe's fastest and wettest watercoaster."
It was as the ride was about to plummet from its highest point down a near-vertical chute that onlookers saw Hayley fall out of the carriage.
She was airlifted to hospital but died of internal injuries while a 10-year-old boy was treated for head injuries after he was hit by the teenager as she plummeted to the ground.
The theme park was packed with families over the Easter holidays when the accident happened.
The charge against Oakwood Leisure, who must also pay £80,000 costs, was brought under the Health and Safety Act 1974 by Pembrokeshire office of the Health and Safety Executive.
Vital checks to a T-bar which sits on a rider's legs and a secondary airline-style seatbelt were not habitually made
No attempt was made to check Hayley had properly put in place either safety restraint
The manufacturers had expressly drawn attention to the importance of staff making the basic safety checks
CCTV footage found an average of 29.2% of more than 4,000 people who used the ride over a period were not safety checked
On the day Hayley died, 87.7% of all passengers were not checked to see that the T-bar was in place and the seatbelt properly fastened
HSE evidence in court
The charge accused the park of failing to ensure, so far as was reasonably practicable, that visitors were not exposed to risks to their health and safety.
The prosecution acknowledged that Oakwood Leisure did have a proper training scheme in place for staff overseeing rides.
They were instructed to push down on the Hydro's T-bar restraint and pull up on the seatbelt to make sure both were properly fastened.
But the company did not have a way of checking that staff properly carried out their instructions, and this only became apparent when CCTV film of the ride was analysed in the safety investigation.
Proshant Popat, for the defence, told the court the company accepted full responsibility.
"It came as a considerable shock to those in positions of management in the company to see what they saw on the footage."
An inquest into the teenager's death returned a narrative verdict stating that "Hayley was ejected from the Hydro ride because she was not properly restrained and died as a result of the injuries she sustained."
The jury had been told not to consider a verdict of unlawful killing for legal reasons.
Standing 121ft (36.9m) tall, the Hydro ride is just 34ft (10.4m) shorter than Niagara Falls. Its 24-seater boat drops down a near-vertical chute into a plunge pool, creating a 45-foot (13.7m) wave.
The ride was closed for 12 months after Hayley's death.
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