The child had appeared to slip out under the safety harness on her seat on the Air Maxx 360 at the Royal Adelaide Show, a witness told The Advertiser newspaper. "She was hanging by her legs off the ride, trying to block herself.
She went flying through the air," Malinda Dunwoodie was quoted as saying.
The child was rushed to a nearby hospital, where she died.
Police and the government's safety authority is investigating the incident, The Advertiser said.
DPA