Amusement rides are 'very safe': engineer

The chance of getting killed on an amusement park ride is one in 834 million, an engineer says.

The rides are safer than flying on a plane or going scuba diving, according to David Eager, who sits on Standards Australia's amusement rides and devices committee.

"The number of deaths on an amusement ride is one in 834 million rides. Aeroplanes is one in 125 million rides. You go scuba diving and that's one in 200,000 dives," he told ABC radio on Wednesday.

"Statistically, they are very safe."

But Mr Eager said people do get thrown out of rides and the deaths on Tuesday were a tragedy.

"When we get catastrophic events like this, where people are killed, they (the risks) are now amplified in people's minds," he said.

Four people died when a raft flipped on the Thunder River Rapids ride at the Dreamworld theme park on the Gold Coast.