In the aftermath of a mid-air collision between two sightseeing helicopters near a theme park, authorities faced distraught families and the potential danger of explosions, as recounted to a coroner.

Nearly three years have passed since the tragedy, and today, coroner Carol Lee commenced an inquest in Brisbane to investigate 11 key factors related to one of Australia’s most catastrophic aviation accidents.

Gold Coast Water Police’s supervisor, Justin Dunn, was among the first responders, arriving at the chaotic scene within minutes.

“It was sheer pandemonium, truly,” expressed acting Senior Sergeant Dunn.

The coroner heard testimonies describing how bystanders performed CPR on an injured woman and administered first aid to a young boy at the scene.

As he approached an overturned aircraft, Dunn was given a chilling warning by a concerned bystander.

“I felt a hand on my shoulder. He said be careful of pressurised fuel lines. As they could explode,” Dunn said.

“It was a mangled wreck.”

Dunn found people dead in an upside down helicopter before discovering passenger Winnie De Silva trapped under the rear of the aircraft.

“I introduced myself and said help was on the way. I asked for a towel to wipe the fuel from her face,” he said.

Shocking footage of the moment the two choppers collided and began to freefall was shown to the inquest as part of counsel assisting Ian Harvey’s opening address.

Multiple passengers used their phones to film one of the helicopters taking off, followed five minutes later by their own chopper’s flight on a bright sunny day above turquoise water.

Just 25 seconds after the second helicopter took off, it collided with a fellow Sea World-branded chopper at an altitude just under 40 metres.

At least one passenger in the second helicopter is shown on video trying to get a pilot’s attention and point out the other aircraft is closing in on them.

“It’s inescapable that neither pilot saw the other pilot’s helicopter,” Harvey said.

“How could that happen? They were two experienced pilots in modern, relatively sophisticated helicopters.”

Security camera footage showed the helicopter piloted by Ashley Jenkinson crash onto a sandbar near Sea World and roll onto its roof.

Jenkinson, 40, died as well as British newlyweds Ronald and Diane Hughes – aged 65 and 67 – and Sydney mother Vanessa Tadros, 36.

Tadros’ husband Simon was at the inquest today.

CCTV on a nearby helipad also captured the helicopter piloted by Michael James coming to a controlled landing near the first chopper’s crash site.

James and nine passengers across both aircraft were injured, most of them seriously.

Last year James died from an unrelated medical condition, Harvey said.

Senior Sergeant Duane Killic was off duty and attending Sea World for leisure when he saw the crash.

“I observed them for five to 10 seconds. It was getting closer and I thought it must be an optical illusion as they can’t be that close,” he told the inquest.

Killic rushed to grab the manifest from the helipad to aid in the rescue effort.

He ran into Tadros who was in a state of “panic” over his family members being on one of the helicopters.

The response to the crash from emergency services, Sea World staff and civilians was “extraordinary”, lead police investigator Detective Sergeant Dane Sheraton testified.

“I think more lives would have been lost without the response of those people,” he said.

The inquest comes months after a damning safety bureau report on the crash.

Harvey said at the time of the crash the volume of flights had been doubled for the peak holiday season.

“It was one of the busiest air corridors in the country,” he said.

The inquest is due to run for three weeks.