Electrical engineering supervisor Scott Ritchie told the coronial inquest into the deaths of Cindy Low, Kate Goodchild, Roozi Araghi and Luk Dorsett at the theme park that engineering supervisor Wayne Cox did not escalate the two breakdowns to him.

Mr Cox told the inquest on Tuesday morning that he himself only knew of one pump failure on the day of the tragedy, and his staff did not tell him of the second failure.

"So are you telling me Mr Cox did not make you aware a major piece of equipment had broken down for the second time that day?" counsel assisting the coroner Ken Fleming, QC, said.

"Yes, I was unaware," Mr Ritchie said.

Mr Ritchie said he was only alerted to the first fault at 12.25pm on the day of the tragedy, and was not told of any others.

The pump broke down three times, with the tragedy occurring minutes after the pump had been restarted the third time by Dreamworld technicians.

Barrister Matthew Hickey, representing the family of victim Cindy Low, questioned Mr Ritchie on his decision to keep the ride running after booking in technician Michael Takac to inspect the south water pump on Thursday, October 27.

Mr Ritchie said he believed there was no safety risk to ride or guests by keeping the ride running.

"History shows us there was a risk," Mr Hickey said.

"I disagree," Mr Ritchie said.

Asked to clarify given four people died, Mr Ritchie said: "The pump was not the cause, in my view, of what happend on that horrible day."

"And that’s because you say there were procedures in place the operators should follow," Mr Hickey said.

"Yes," Mr Ritchie said, but admitted he had not read the ride operation procedures he was referring to.

Mr Ritchie said he was aware of breakdowns on the south pump of the ride on the Wednesday, Saturday and Sunday before the fatal incident and considered the options for the ride as it was the most popular in the park.

Mr Ritchie told the inquest that he considered the safety procedures in place for the ride sufficient, if they were followed correctly.

"To keep that ride in operation safely, I considered when this had happened for a second time on the Saturday that I needed to get some [pump] drive experts down to look at the drive," Mr Ritchie told the inquest.

"I not once thought there was a safety issue with a pump stopping because we had procedures in place which were executed on Wednesday, Saturday, Sunday and the Tuesday to safely bring the rafts home."

Mr Fleming replied: "But not the third time on the 25th of October."

Mr Ritchie said: "On the third time, I don't know what happened then, I don't know if procedures were followed or not, so I can't comment on that."

Mr Ritchie said he believed the ride would be safe as long as procedures were followed.

Mr Fleming: "Did you have in mind that procedures mightn’t be followed?"

Mr Ritchie: "No, sir."

Dreamworld's breakdown policy required that after two breakdowns within 24 hours, a ride had to be shut down and an engineering supervisor called to inspect the ride and authorise its re-start.

A written proposal from Mr Ritchie to install $10,000 worth of upgrades to the Thunder River Rapid Ride’s operations console in August 2015 was also shown to the inquest on Tuesday morning.

The proposal included a way to monitor water levels.

An expert audit after the tragedy determined relatively simple water level sensors installed in the ride could have prevented the tragedy.

Such sensors would have automatically stopped the entire ride when a pump failed and water levels dropped below safe levels.

The safety upgrades were not approved by his manager, Chris Deaves, who told Mr Ritchie the upgrades were not immediately necessary.

In a statement, Mr Ritchie said he was “accepting” of the decision not to install his proposed upgrades, and he was “comfortable there was no urgency to attend to this work”.

Earlier on Tuesday, the inquest heard a proposal to shut down the Thunder River Rapids Ride for 30 minutes during the day to drain the increasingly old and waterlogged rafts was akin to "World War Three".

The proposal was raised by attractions manager Andrew Fyfe who said the rafts were no longer able to cater for the full days' trade.

The inquest continues.