A Dreamworld staffer has agreed there was a “total failure by everybody” to ensure safety on the Thunder River Rapids ride, on which four people died in October 2016.

An inquest into the deaths of Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi resumed on Monday at the Southport coroners court. The four tourists were killed when the ride malfunctioned.

Maintenance planner Grant Naumann was asked by counsel assisting, Ken Fleming QC, if there had been a “total failure by everybody” to identify safety risks with the 30-year-old ride.

“In hindsight, yes,” Naumann replied after a long pause.

Among the issues Fleming suggested could have been identified on the ride were pinch points on the conveyor belt and potential problems that would be created by a water pump failure.

The fatal accident occurred when water levels dropped after a pump failed, leaving a raft stranded on the conveyor belt. The raft carrying the four victims collided with the stationary raft, forcing both to flip and causing the visitors to be fatally injured by the ride’s machinery.

Naumann said in his time at Dreamworld he was unaware of the ride being inspected by an engineer for safety issues.

Earlier on Monday, Naumann had agreed some maintenance operations may have been deferred for financial reasons but he said he had never been told he could not attend to matters of safety on cost grounds.

The inquest also heard the emergency stop button on the control panel of the ride was not subject to regular maintenance checks.

Dreamworld’s maintenance supervisor, Stephen Murphy, told the inquest he had never used the emergency stop button on the main control panel of the ride.

Murphy said he had no idea what the button exactly did and despite using other emergency stop buttons during his daily checks, he had never pressed the control panel button.

“That button was not a part of our pre-operational checks,” Murphy said.

The inquest also heard Murphy had no knowledge of incidents on the ride in 2001 and 2014 when rafts had collided in similar circumstances to the fatal incident in 2016. He said he did not believe at the time of the incident that the rafts colliding was an obvious risk on the ride.

Barrister Matthew Hickey, representing Low’s family, asked what would happen if rafts did collide on the ride.

“We all know the consequences once that did happen,” Murphy said.

“Did you know it had happened before?” Hickey asked. Murphy replied: “No.”

Former Dreamworld employee Stephen Buss, who was fired after the 2014 incident, is expected to give evidence on Tuesday. The general manager of Dreamworld, Troy Margetts, is also expected to be called to give evidence during the two-week window.

The Queensland premier, Annastacia Palaszczuk, said she expected “shocking” details would come out during the second part of the inquest.

“I know the worst phone call I have ever received as premier was when the police commissioner rang to tell me about this tragedy,” she told Channel Nine’s Today on Monday.