An inquest is examining the deaths of Year 5 and 6 students Addison Stewart, Chace Harrison, Jye Sheehan, Jalailah Jayne-Maree Jones, Peter Dodt and Zane Mellor.
They were among classmates enjoying end-of-year celebrations at Tasmania's Hillcrest Primary School in December 2021 when a freak dust devil wind gust lifted the castle and inflatable equipment into the air.
Rosemary Gamble, operator of Taz-Zorb which set up the equipment, was under a gazebo near the castle when a small gust of wind arrived.
"I put my hand up to hold the gazebo down .. then I looked over and you could see the front corner of the jumping castle moving up and down," she said on Thursday via video link to the inquest.
"Everything was just swirling around and I looked up and the castle was swirling in the air.
"It was so fast. It was there and then it wasn't. As you blinked, it disappeared. The jumping castle sat in it (the dust devil)."
The dust devil, a short-lived mini-tornado, was about 4m wide, and "enclosed" the jumping castle.
"When I looked at it, it reminded me of the scene from the Wizard of Oz with the house going up," Ms Gamble said.
The inquest is examining issues including safety processes and the application of relevant national standards.
Ms Gamble said she had no formal training when she set up Taz-Zorb in 2012 and bought the castle from a Chinese supplier in 2015.
She said it didn't come with a manual and conceded Taz-Zorb's process for tethering the castle wasn't based on any formal instructions.
It was held down by four pegs on the day of the tragedy despite having eight available tether points.
There was no practical reason why all eight points hadn't been used, Ms Gamble said.
Ms Gamble, who will continue giving evidence on Friday, was in 2025 cleared of criminal breaches of workplace health and safety regulations.
The inquest, which started in September and will sit again in February, will also hear from a retired police officer who attended the scene.
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