Peter Dodt, Zane Mellor, Jalailah Jayne-Maree Jones, Jye Sheehan, Chace Harrison and Addison Stewart died during end-of-year celebrations at Hillcrest Primary School on December 16, 2021.
A long-awaited inquest began in Tasmania on Monday following years of delays due to criminal proceedings against the castle's operator Rosemary Gamble.
Ms Gamble operated Taz-Zorb, which set up inflatable equipment at the school. She was found not guilty of criminal workplace health and safety breaches in 2025.
The events of the day and the tethering of the castle and other devices would be placed under "extensive examination", counsel assisting the coroner Maree Norton said on Monday.
"Although the jumping castle had eight anchor points, evidence collected by police suggests the castle was secured by only four ... pegs on the day," Ms Norton said.
An inflatable arena containing inflatable Zorb balls had 32 anchorage points but was held down by only six pegs, she said.
Ms Gamble had set up inflatable equipment at previous end-of-year celebrations at the school, which had been "very successful" events, Ms Norton said.
She was supervising on the day and had a policy of not operating the castle if winds were tipped to exceed 25km/h.
The Bureau of Meteorology forecast for December 16 was light winds, reaching 15 to 20km/h by the evening, Ms Norton said.
Several witnesses, including teachers and nearby residents, said the morning was largely windless before a "mini-tornado" hit around 10am.
The coroner will hear evidence from a weather expert that cool sea air coming into contact with warm air caused an unprecedented and unpredictable "dust devil", Ms Norton said.
The jumping castle was lifted 16 metres into the air and went 60 metres across the oval, with witnesses seeing it twisting.
Three children were also injured in the incident.
Other similar dust devils were reported in different sections of Devonport, the city where the school is located, around the same time, Ms Norton said
The inquest will probe whether education department practices and related national standards were deficient at the time.
The scope also includes an examination of weather monitoring, what risk assessments were undertaken and the processes of Taz-Zorb.
In 2025, the Magistrates Court found Ms Gamble could have taken further steps in relation to the castle's anchorage, but even if she had, it would have made no difference to the outcome.
The coroner can make different findings but cannot make rulings of criminal guilt.
Zane Mellor's mother Georgie Burt will be among witnesses to give evidence on Monday, with further hearings on Tuesday, Wednesday and Friday.
Further hearings will be held in November and February.
Preparations for the inquest were also slowed by a legal dispute between the coroner and workplace regulator over document access.
