Two New Zealand couples who miraculously survived a fatal helicopter crash on the Gold Coast have remembered the "traumatic experience" as a "nightmare" and hailed their pilot as a "hero".
Edward and Marle Swart, and friends Riaan and Elmarie Steenberg were all holidaying on the Gold Coast from Auckland when their scenic helicopter crashed into another helicopter mid-air killing four people and severely injuring three more.
The Australian Transport Safety Bureau (ATSB) is investigating the crash, with the cause of the collision yet to be determined.
In a statement, the couples said they were "completely devastated by the horrific helicopter accident".
"A fun, five-minute joy ride on vacation to Australia turned into a nightmare," they said.
"Our deepest sympathies and sincere condolences to the injured and the deceased and their families.
"We are grateful and blessed to have been spared but very sad for the people who lost loved ones and the little ones and mum fighting for their lives in hospital. Our hearts are so heavy for them.
"Our gratitude goes out to every bystander who ran to help, every police officer and emergency services personnel who helped us with our immediate needs, keeping us calm and making us comfortable.
"We saw mateship in action. Australians come together to help in time of need."
Pilot of helicopter hailed a 'hero'
The group thanked the hospital staff for their "kindness and compassion during a traumatic time" and their pilot, who they described as a "hero".
"To our pilot, who, through all the chaos, landed the helicopter safely, keeping us and other bystanders safe," they said.
"You are our hero. Thank you so very much."
They said they were assisting the ATSB and Queensland police with their investigation.
It comes as aviation experts have said the number of joy flights departing from Sea World Helicopters' helipad will be among the factors that transport safety investigators will examine.
Sea World Helicopters pilot Ashley Jenkinson, New South Wales woman Vanessa Tadros and UK couple Diane and Ron Hughes were killed in the mid-air collision on Monday afternoon.
Three passengers remain in hospital: Geelong woman Winnie De Silva, 33, and her son, Leon, 9, were critically injured, along with Ms Tadros's son Nicholas, 10.
Aviation experts Ron Bartsch and Neil Hansford have said at this stage it appears there was not a mechanical fault with the aircraft.
To determine the factors involved, ATSB investigators will analyse flight procedures, fixed footage from the helicopters, any passenger or witness footage and accounts and CCTV as well as evidence from the aircraft.
Mr Hansford told the ABC one practice that may come under scrutiny is the number of joy flights taking place, some as quick as five minutes in duration.
"That's a lot of movements if you're doing a five-minute or even 10-minute land, get the people off, get the people on and go again," he said.
"That's a fairly stressful environment.
"I think it's the business model that's existed for years and, with good pilot management, we haven't had an accident."
'Multiple lines of inquiry'
Mr Hansford said he believed the incident would prompt a major review of the helicopter operations from the helipad adjacent to the Broadwater, beside a major tourist attraction such as Sea World.
"Helicopter joy flights are, in themselves, absolutely safe," he said.
"But there will be a complete rethink, I would think, by Queensland Maritime, Queensland Police, but most importantly, the Australian Transport Safety Bureau and the Civil Aviation Safety Authority."
ATSB chief commissioner Angus Mitchell said the collision had caused the main rotor blades and gearbox to be removed from the ascending aircraft, which then crashed down.
At a press conference on Tuesday, Mr Mitchell said the ATSB would be looking at multiple accounts from witnesses and other evidence, along with the flight procedures.
"We know it's a busy time of year. We know helicopters are in and out of that Sea World helipad constantly throughout the day. So, we'll certainly be looking at multiple lines of inquiry here around the procedures that were in place and, potentially, what has helped contribute to such a tragic outcome," he said.
Professor Bartsch said it appeared that the two aircraft did not see each other at the time.
"Unlike airspace at major airports — [such as] Brisbane and Sydney — the aircraft aren't under positive radar control, so the only two means that they've got of maintaining separation is by visual and oral means," Professor Bartsch said.
"So, they were both presumably on the same radio frequency.
"Because the two aircraft operated by the same operator, they would no doubt have procedures involved in taking off and landing.
"At the moment, it's all visual flying and see-and-be-seen principle and, obviously, that has to happen, but if it gets to the extent that the congestion poses a safety risk, then there may be a need to reconsider the classification of that airspace in terms of how it is managed," he said.
Weather conditions likely not a factor
Professor Bartsch said it was too early to speculate as to what caused the crash but said he has full confidence in the ATSB investigation.
Both helicopters were EC-130s, with passengers sitting next to the pilot. Professor Bartsch said this may be a consideration when the accident is investigated by the ATSB.
"[The ATSB] will look at all relevant factors, and that includes human factors. It includes the operating procedures of the aircraft, they will have a look at the consideration of the airspace and how pilots maintain separation and it will have a look at the background of the pilots in terms of their flight and duty times, their experience and also the mechanical aspects of the aircraft," he said.
Professor Bartsch said it did not appear that there were any mechanical failures or adverse weather conditions at the time.
Sea World Helicopters did not answer questions from the ABC, but provided the same statement issued after the crash on Monday afternoon.
"We and the entire flying community are devastated by what has happened and our sincere condolences go to all those involved and, especially, the loved ones and family of the deceased," a spokesperson for Sea World Helicopters said.
"We are cooperating with all the authorities, including the Australian Transport Safety Bureau (ATSB) and the Queensland Police. As it is now a police investigation, we cannot provide any further information at this stage."
