Hearings examining the deaths of students Addison Stewart, Chace Harrison, Jye Sheehan, Jalailah Jayne-Maree Jones, Peter Dodt and Zane Mellor resumed on Tuesday.
The kids aged between 11 and 12 were enjoying end-of-year celebrations at Tasmania's Hillcrest Primary School in December 2021 when a dust devil picked up the castle and other inflatable objects.
The inquest was also told the castle didn't meet the bar to require registration with workplace regulator WorkSafe Tasmania and national operating standards lacked legal teeth.
Retired teacher Stephen Fenn, who taught some of the Year 5 and 6 children who died, was supervising near the castle when he felt the wind pick up.
"I turned around and I could see (the wind) swirling around. As it got close it increased a little bit and brought up a lot of dust and grass clippings," he said.
"It went from one to 1000 in a split second. To me it felt an awful lot more than 100km/h.
"It could have gone anywhere on that oval. It went straight for the jumping castle, it seemed like."
Mr Fenn, who started teaching at the school in 2000, said it was a sunny day with hardly any wind before the dust devil, describing a short-lived whirlwind, hit.
He heard a "whoosh" sound before seeing the jumping castle come down from the height of a telephone pole and land on the other side of the oval, he said.
Mr Fenn ran to help Jye Sheehan and saw several students laying on the oval before going to hospital to identify bodies including Addison Stewart's.
"I didn't know she had passed away," he said.
"That was ... very confronting to see that little girl there."
The December 16 incident forced Mr Fenn into an early retirement because he was unable to return to the classroom with the same care and love, he said.
It affected his mental health, caused depression and meant he was always on the lookout for danger.
"I fear seeing parents or children from the school, because of my feelings or their reaction," he said.
The inquest, which began in September after delays due to criminal proceedings, is examining the causes of death, safety protocols and national standards.
Standards covering inflatable jumping castles were voluntary and had limited legal force, counsel assisting the coroner Maree Norton said.
In 2021, the jumping castle was among a category of "blowed" inflatable devices that didn't need to be registered with regulator WorkSafe Tasmania, she said.
Whether operating manuals were provided to Rosemary Gamble, the owner of Taz-Zorb which set up the equipment, was a "matter of controversy" before the inquest, Ms Norton said.
Ms Gamble claims she was not given a manual by Chinese supplier East Inflatables but downloaded one from their website.
She will give evidence on Thursday.
The castle was tethered at four of eight anchorage points, the coroner has been told.
Ms Gamble was found not guilty in 2025 of criminal workplace safety breaches related to the incident.
