Olivia Inglis died after she was fatally crushed by her horse when the duo tumbled over a jump at the Scone Horse Trials in March 2016.

Her death came just weeks before 19-year-old Caitlyn Fischer also died from a blunt force head injury when her horse fell and landed on her at the Sydney International Horse Trials in April 2016.

Deputy state coroner Derek Lee is looking into the circumstances of both deaths at an inquest in the NSW Coroners Court.

Elite equestrian Paul Tapner was lucky to survive a rotational fall when his horse fell at the Badminton Horse Trials in the UK in 2017.

Tapner says the jump Olivia died on was appropriate, but not safe.

"If I was a rider there I would have liked something to be changed about that jump," he told the inquest on Tuesday.

"I would be exceptionally unhappy to jump that without a discussion with the course designer and technical delegate about how it could be made safe."

Tapner was concerned that while there were a number of variables or risks presented by the jump, only two were addressed.

The course designer at Scone painted the jump white and raised the back fence by three centimetres but didn't include a ground line to help orient horses or use frangible pins which allow the top element to fall when clipped.

These omissions led Tapner to conclude the jump was "unsafe".

"Far too many variables and far too many risk-mitigating features are not included," he said.

An incident investigation revealed the jump at which Olivia died did not meet at least three Federation Equestre Internationale cross country course guidelines.

Tapner was the only current professional rider giving evidence on Tuesday.

Other course design experts at the inquest included Brits Mike Etherington-Smith and Alec Lochore and Australian Grant Johnston.

All three said they believed the jump was safe, with Mr Etherington-Smith emphasising the FEI guidelines were not rules.

"It's not a black and white science - what we do," he said.

Mr Lochore similarly said he was "perfectly comfortable with that fence".

However, all three said they themselves would not have designed the jump as it stood.

The trio said they would have included a ground line, while the UK experts testified they would have built the jump with frangible pins.

"We live in a world of 'what ifs?'" Mr Etherington-Smith said.

"I would have done it because it helps mitigate the risks. All course designers have different styles, that's not to be critical of anyone in the room."

The experts were unanimous that the jump on which Caitlyn Fischer died in Sydney was safe and attributed her fall to an error from her horse.

Australian Associated Press