A seven year old girl died due to gross negligence and failure to correctly install a fairground attraction, a court heard.
Summer Grant, died from multiple injuries after a strong gust of wind swept the inflatable across a park in Harlow, Essex, on March 26 2016.
Shelby Thurston, 25, and husband William Thurston, 28, from Cambridgeshire, who were responsible for the bouncy castle are jointly charged with gross negligence manslaughter and deny the charge.
Summer's father, Lee Anthony Grant, told the court that he went to the fair with his daughter Lily who was then five years old, his mother, Sharon Stephens, his sister Tasha Grant, and Summer, who was seven at the time.
He said that he went to the fair between 4 and 5 o'clock and he described the weather as: "Windy, nothing to think that a bouncy castle would blow away. It was a little bit windy, wasn't anything mad.
Mr Grant said: "We went to the waltzer, me and both my daughters. Then we went to both bouncy castles."
The court heard that it cost Mr Grant £3 to go on both the bouncy castles for both Lily and Summer together.
"They both went onto the dome right first, - they both went on the slide bouncy castle, and Summer decided to go back to the dome one, because she preferred that one", he said.
"I just heard my mum scream no - and within seconds the bouncy castle had blown up in the air, and I just remember screaming, 'My daughter's on the bouncy castle.'
"I just saw a cable or wire, I don't know if it was a rope or something, just fly up in the air and it just blew in the air and kept on going down the field.
"I just started running after the bouncy castle down the field.
"It was windy, but not as windy as I thought it would be to fly a bouncy castle all the way down a field the way it did.
When asked if he ran after the bouncy castle, Mr Grant said: "I did."
He added: "It went about 30-50 feet in the air, and it was rolling down the field, just rolling and rolling and rolling and rolling. And I think it hit a tree.
"At the end of the field it came to a halt and hit a fence.
"I couldn't find her, I couldn't find the entrance to the bouncy castle because it had been deflated by the time it got to the end."
Lee's voice broke as he said: "Somebody went in and got her and pulled her body up. An ambulance was called by somebody, I don't know who."
Kevin John Smith went to the funfair at Harlow Park on the day of the incident.
He said that he went to the park at around 3 15pm "Lola was loving it, she wanted to go on everything. I had to go with her because she was on her own."
He said that his daughter, Lola, was on a dome: "Lola wanted to go on the slide one but it was wet - I saw them starting to deflate it, and I said no.
"It really started to get windy. There was railings in front of one of the rides that just blew over.
"We started to go to another dome one, we didn't get to it. There was a gust of wind, the dome just started to move, and it just went down a hill.
"It just started tumbling, cartwheeling, it just kept going down the hill. In any direction it could really, it kept going down the hill.
"I shouted to my partner, there's a little girl in there and I started running after it.
"It just kept going straight down a a hill and it hit a fence at the bottom of the hill.
"When the gentlemen took her out the castle he lay her on the floor and her father was by her head."
The court heard that Smith kept Summer warm with his coat - he said that she was already in the first aid position.
Smith said he just gently pulled Summer's tongue out of her mouth.
The ambulance then arrived and took care of Summer. Smith then described "a couple of workers folding up" the bouncy castle and lifting it into a trailer.
Charlotte Edwards is the partner of Kevin Smith, and also took to the stand.
She said the weather was "raining, on and off - when we arrived it was quite wet, windy throughout.
Miss Edwards said: "My partner told me, he shouted out to me that someone was on it, and it had blown away.
"I stood back for a little bit because I had my daughter in a pushchair, because I thought that he would come back really quickly - so I kept my daughter with me, and just held back for a while."
The court heard that Miss Edwards took photos of what happened, which she later gave to police.
Miss Edwards said: "By the time I walked to get a little closer, it was already at the bottom of the hill.
"I saw it was getting rolled up and put onto the back of a car - or something slightly bigger."
The trial continues tomorrow at Chelmsford Crown Court and is expected to last three weeks.