The couple from Cheshire died at the scene, as did fellow passenger Vanessa Tadros, 36, from New South Wales, and pilot Ashley Jenkinson, 40.
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Emergency crews were at the scene where one of the helicopters was upside down on the ground
A year on from the accident, the Australian Transport Safety Bureau (ATSB) has released an interim report that notes a toxicology report for Mr Jenkinson shows a positive result for cocaine metabolites.
However, the report concludes that the “very low concentrations” means it was “unlikely” that this would have impaired his flying ability.
Chief commissioner Angus Mitchell said the metabolite levels suggest “exposure was not likely to have occurred in the 24 hours prior to the accident”.
He added: “It is important to note while this is a substantive and comprehensive interim report, the ATSB is yet to make formal findings as to the contributing factors that led to this accident as we are continuing our analysis of that evidence.”
Mr Jenkinson’s family has welcomed the interim report, according to local media, but asked those who knew him to not let it “tarnish the memory” of the pilot.
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They are also urging people to read the full report which found “multiple contributing factors to this terrible accident”.
The ATSB investigation has also found some of the passengers’ seatbelts were not fitted correctly, partly due to “interference from their lifejackets”.
Mr Mitchell said this was “not attributed to the tragic outcomes in this case”.