Four people died and nine people were injured when two helicopters collided mid-air on the Gold Coast Broadwater in January 2023, during the peak of the busy summer holiday season.
The Australian Transport Safety Bureau handed down its final report into the crash on Wednesday, more than two years after the collision.
The report found an inbound taxiing call from one of the helicopters carrying five passengers failed to register to the second chopper boarding six people on the helipad.
By the time the second helicopter took off, the ground crew's advice that the air was clear had become obsolete.
The first helicopter waited for a taxi call from the second helicopter to separate to avoid a mid-air collision or if conditions changed, but it never came.
"Neither pilot was aware of the existence of faults in the radio of VH-XKQ that likely prevented broadcast of the taxi call," the report said.
It also said the departing pilot made the taxi call but it was not broadcast due to a fault in the antenna that had existed for days.
That allowed it to receive calls but not deliver them.
Without the radio calls, neither pilot had information available to target their search for the other helicopter.
The report found limitations in visibility from both helicopters, the failed radio transmissions, and competing priorities when looking at boats and other aircraft led to the mid-air crash.
The report also found Sea World Helicopter's system of radio calls, hand signals and conspicuity devices, intended to warn of the presence of another helicopter, was flawed.
This meant that both of the pilots formed an incorrect understanding about the location of the other helicopter.
The ATSB also found evidence that passengers on both of the helicopters were incorrectly restrained but couldn't determine the level of contribution to their injuries.
Investigators said the helicopters were changed a week before the crash while the helipads had been swapped a year before which contributed to a loss of safety processes during the swap.
The helipad location change also increased the risk of a collision between helicopters, it said.
The new aircraft lacked company radio communications with no mandate to make proactive calls, no live traffic displays, and the pilots were not familiar with the systems, the report found.
Pilot Ashley Jenkinson, 40, British couple Ron and Diane Hughes, 65 and 57, and Sydney mother Vanessa Tadros, 36, died in the crash.
Ms Tadros' son Nicholas, 10, underwent serious surgeries following the crash while Victorian mum Winnie de Silva, 33, and her nine-year-old son Leon were hospitalised.
The pilot of the second chopper, Michael James, managed to land his aircraft safely, but he and two of his passengers were injured by flying glass when its windshield shattered.
Shine Lawyers, who represent several people injured in the crash and those traumatised by what they witnessed, were keenly awaiting the report to inform civil proceedings.
Claims have been made against Sea World Helicopters of up to $925,000 per person and the release of the report will inform any further action, litigation specialist Roger Singh said on Tuesday.
"We will examine the findings of this report with a view to identifying other potential defendants and further damages which may be sought," he said.
"This was such a profoundly unnecessary loss of life which must be prosecuted fully to ensure it never happens again."
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