Dreamworld's Thunder River Rapids ride was unsafe when four tourists, including a New Zealander, were killed and the Gold Coast theme park had shown little learning from past malfunctions, an inquest has been told.
Giving evidence today was WPHS engineer David Flatman, whose workplace health and safety report into the fatal ride identified major faults.
These included missing slats from the conveyor, excess corrosion, crumbling concrete and unidentified controls.
The report found the ride was "unsafe" and there had been "little learning" from previous incidents.
Mr Flatman's report outlines how the leading raft became grounded after a sudden drop in the water levels when the south pump failed.
Missing slats on the conveyor belt created a void large enough that the rear of the second raft was drawn into the gap.
"Both operators failed to detect the drop in water level and activate the emergency stop," the report states.
"This resulted in the rafts colliding and three passengers being drawn into the gap."
A crucial delay in stopping the ride caused the jammed raft to be shaken and a fourth person to fall from his seat and into the machinery.
The inquest also heard from a Dreamworld employee who said she had met with engineering consultants to conduct a park safety audit on the day the four people were killed in October 2016.
Nichola Horton, as operations system administrator assisted in a review of engineering safety systems - primarily of rides - to ensure operators were following procedure.
Ms Horton, whose role it was to draft and amend safety procedures, said that, in hindsight, procedures should have been updated so that ride operators understood the actions of pressing the emergency button.
She said there had been talks about changing the emergency stopping procedures to a one button stop, but was told "it could not be done" because the ride was too old.
New Zealander Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi died after the water pump malfunction.
The inquest was also told a US safety audit firm has been given a "final opportunity" to co-operate with the legal proceedings.
Counsel assisting the inquest Ken Fleming QC said there had been repeated attempts to contact JAK, which carried out safety inspections of rides at Dreamworld before the 2016 Thunder River Rapids disaster.
Despite repeated attempts, the company has failed to respond and it could face adverse findings if it does not respond, the inquest was told.