The 19-year-old died from a blunt force head injury when her horse erred before a jump, fell and landed on her at the Sydney International Horse Trials in April 2016.

Ms Fischer's death came just weeks after 17-year-old equestrian Olivia Inglis was similarly killed during a March 2016 eventing competition in the NSW Hunter region.

Deputy state coroner Derek Lee is examining the circumstances surrounding both tragic deaths in a two-week inquest at the NSW Coroners Court at Lidcombe.

Counsel assisting the coroner, Peggy Dwyer, during her opening address on Monday, said the beautiful, "clever and vibrant" teenagers were both competing at extremely challenging levels and had spent many years working their way up to qualify with their respective horses.

They both died during the cross-country phase of eventing, which "is widely recognised as one of the toughest equestrian disciplines for both horse and rider".

Dr Dwyer said she expected evidence that Ms Fischer's mother, registered nurse Ailsa Carr, saw her daughter and horse Ralphie fall as they attempted the second jump of the cross-country phase.

The horse seemed to be progressing well until he appeared to become distracted and missed his stride.

"She was the first to reach her daughter and when she got there she found that Caitlyn was motionless," Dr Dwyer said.

"In short, Ailsa was able to tell immediately that Caitlyn had passed away."

Ms Fischer's coach, Christine Bates, said she was shocked when she ran to the scene because "it never crossed my mind that she might be deceased".

She said her pupil told her before the accident that Ralph felt "a bit strong" in their warm-up but the coach wasn't concerned and was pretty confident he'd settle on the course.

In regards to the fatal jump, they discussed making sure the horse was watching the fence and wasn't distracted upon approach.

Ms Fischer's death came after Ms Inglis also died in a rotational fall on her horse Coriolanus at the Scone Horse Trials in March.

The 17-year-old had competed with Coriolanus at almost every cross-country event in NSW and their record was impeccable, Dr Dwyer said.

"From a young age, she loved eventing and she was determined to achieve in it at a high level," the lawyer said.

She expected evidence that the teenager's mother Charlotte Inglis, herself a highly-respected rider, was concerned about jumps on the course that day.

She discussed those concerns before her daughter's death with Olympic champion Shane Rose.

The inquest will consider a number of issues including whether safety procedures at NSW equestrian events were adequate and whether physical aspects of the courses contributed to the deaths.

Dr Dwyer noted Equestrian Australia had already introduced significant changes to the sport.

Australian Associated Press