Summer Grant died when the fairground castle she was playing in was picked up by strong winds and carried away at an Easter fair in Harlow, Essex, on 26 March, 2016.
Fairground worker William Thurston, 29, and his wife Shelby Thurston, 26, both denied manslaughter by gross negligence and a health and safety offence following the incident.
Mrs Thurston told a court the operating instructions for the bouncy castle had been destroyed in a fire, after they had been at another fairground, which faced opposition.
They were accused of failing to adequately anchor the bouncy castle and not monitoring the weather situation closely.
Tracy Ayling QC told the court: “Summer was playing in a bouncy castle that was one of the fair’s attractions run by these two defendants.
“While Summer was in the bouncy castle, it blew away from its moorings, bounced 300 metres down a hill; having hit a tree, it came to rest.”
Ms Ayling said Summer’s father heard a scream and ran after the bouncy castle but it was moving too fast for him to catch it.
More from UK
Former SAS commander Lieutenant-General Mark Carleton-Smith is new Army chief
Warwick University suspends students over rape jokes sent on group chats
‘Former Pink Panther diamond thief’ wanted over rings stolen from London art fair
UK retail sales record worst fall in 23 years
Concern grows for missing Frightened Rabbit singer Scott Hutchison
Southampton vow to never return after Swansea hotel scandal
“He turned and saw that the dome inflatable had lifted into the air, appeared to hit a caravan before flipping over,” the prosecutor told the court.
“He said ‘my daughter’s in there’.”