Helicopter pilot did not hear radio call before deadly Sea World crash, preliminary report finds

The pilot of a helicopter coming into land did not see a second helicopter or hear a radio call before the tragic mid-air collision on the Gold Coast, a preliminary report has found.

The horror crash unfolded on January 2 when two helicopters collided near the Sea World theme park, killing pilot Ash Jenkinson, British newlyweds Diane and Ron Hughes, and Sydney woman Vanessa Tadros.

Multiple people were also injured in the horrific crash, including Melbourne mother Winnie De Silva, her nine-year-old son Leon and Tadros' son Nicholas, 10.

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Australian Transport Safety Bureau (ATSB) Chief Commissioner Angus Mitchell today detailed the agency's preliminary findings into the incident.

The two helicopters - operated by Sea World Helicopters, a separate corporate entity to the theme park - took off from separate helipads more than 200m apart.

The aircraft were meant to follow the same counter-clockwise orbit before landing at the opposite helipad from where they took off.

"The two helicopters collided at an altitude of about 130 feet, 23 seconds into the departing helicopter's flight," Mitchell said.

"The helicopters were operating in a non-controlled or class G space where pilots use a common traffic advisory frequency to make radio calls to announce their positions and intentions and where necessary to arrange separation."

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Mitchell said the pilot of the first helicopter saw passengers boarding the second chopper and believed it would pass behind them after take off.

The pilot of the already airborne helicopter said he didn't recall a taxi call being made to announce the other aircraft's intentions to depart.

"This does not necessarily mean that a taxi call was not made," he said.

"The pilot of the arriving helicopter did not see the other helicopter actually depart the helipad."

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Mitchell said although video showed the helicopters in the air at the same time, it did not mean they were visible to the respective pilots.

"This investigation will look closely at the issues both pilots potentially faced in seeing the other helicopter," he said.

The agency has created a 3D model of what the pilots could have seen to figure out the "impediments" to seeing each other's helicopter.

Mitchell said investigators will look at the procedures of operating helicopters in the Sea World area, the regulatory surveillance of the operator and the use of the traffic collision avoidance system.

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He stressed it was a preliminary report but more analysis of what led to the tragedy would continue and any safety reforms are yet to be determined.

"I am acutely aware that those who lost a loved one in this accident and the survivors who are still recovering from significant physical and mental injuries and their families want only to understand how the tragedy unfolded but equally and most importantly why had occurred," he said.

"And why did the safety equipment processes and procedures that are designed to prevent an accident like this not work on this occasion."

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