A former Dreamworld employee has claimed he noticed a "potentially fatal flaw" while working on the Thunder River Rapids ride when it first opened.
The ride was at the centre of a fatal incident on Tuesday that left four park visitors dead.
It is understood the fatal incident was caused when a pump failed, causing the water level to lower and another raft to be stuck. The raft containing the passengers then collided and mounted the stationary raft, causing it to flip.
Two passengers were trapped between then conveyor belt and the raft with another two trapped under the water.
Jon Armstrong has told news.com.au he had worked on the ride on a casual basis for about six months in 1987, not long after it was built.
He claimed both he and his colleagues had encountered a “similar problem” one day which saw a raft flip on the conveyor belt while still attached to rope mooring.
The 51-year-old said he had been placed on “start-up duties” for the ride that day, which involved him walking the riverbed before the pump started.
He was tasked to check raft inflation pressure and ensure all rafts were untied and ready to ride.
“I was unaware this particular morning that one raft had two mooring lines attached by the overnight maintenance crew, the second rope being hidden on the far side of the raft and submerged,” he told news.com.au.
He explained that having these lines still attached meant that when the ride started, the raft became stuck and caused three other rafts to flip on to the conveyor belt.
Like a domino effect, four more rafts then mounted those that had flipped.
“It’s lucky there was no one on board because if there had been, their body parts would have been pushed under the water,” he said.
“Luckily we had not allowed guests in to ride yet but those of us present at the time all agreed that this was a potentially fatal flaw.”
Mr Armstrong said a formal investigation followed the incident and new safety procedures were introduced as a result.
He claimed the park introduced more checks to ensure the rafts had been untied such as the installation of new cameras and the relocation of the emergency shutdown switch to the control room.
Mr Armstrong, an IT worker, said he felt there should be an automatic shutdown if a raft was unable to move up the conveyor belt.
He said he felt the ride needed a “redesign” and doubted that he would ride it until Dreamworld changed the format.
It’s not the only time Mr Armstong had concerns about Dreamworld rides.
In 2007 he claimed he was employed by an engineering company that was commissioned to repair weld the Giant Drop and Tower of Terror.
“The lead welder/engineer came back at the end of the day and told me he had serious doubts regarding the safety of those two rides as the fatigue damage his team repaired that day was extensive and indeed needed repeating a short time later.”
Dreamworld to host memorial day on October 28
Dreamworld’s management have offered “heartfelt thoughts” to the families of victims of Tuesday’s tragedy.
“In particular we would like to acknowledge the tragic circumstances and extraordinary loss for their children,” a statement read on Wednesday night.
Management also stressed the park had been fully compliant with safety requirements at the time of the incident.
“Park safety is our priority. Dreamworld would like to assure the public and our guests that at the time of the incident the park was fully compliant with all required safety certifications,” the statement read.
A spokesman said the Thunder River Rapids ride had successfully completed its annual mechanical and structural safety engineering inspection on 29 September 2016.
“As per regulations, this safety audit was conducted by a specialist external engineering firm. Details of this external audit will be provided to the Coroner and workplace safety investigators.”
“Our safety procedures have been endorsed by Mr David Randall, Managing Director of DRA Safety Specialists.
Mr Randall said: “In my capacity as a Safety Professional, I have been involved with Ardent Leisure conducting safety audits against the National Audit Tool over a period of the last six years.”
Mr Randall said Dreamworld’s annual audits had resulted in continuous improvement in the management of safety.
Dreamworld will host a memorial day at 11am on Friday October 28. Entry proceeds will go towards Australian Red Cross.
“We hope this will be considered the start of the healing process for all concerned,” a spokesman said.
The park will also host a private ceremony for Dreamworld staff, friends and emergency services.
DREAMWORLD'S DARKER DAYS
• June 10, 2009: Joy ride chopper crashes into car park, pilot and tourists injured
• 2011: Two incidents at Tiger Island including handler being bitten by Kato the tiger.
• November 8, 2013: bushfire at Coomera sparks entire site evacuation at the theme park.
• February 17, 2015: BuzzSaw was shut down due to safety issue.
• April 2016: Man falls off log ride, closing it for a number of days.
• October 25, 2016: Four people killed on Thunder River Rapids ride.