The British family and pilot aboard the ill-fated Sydney Seaplane that crashed on New Year's Eve died of head injuries and drowning, a UK coroner has revealed.
The seaplane, piloted by Canadian Gareth Morgan, crashed into the Hawkesbury River on December 31 with high profile UK businessman Richard Cousins and his family on board.
There were no survivors.
The Australian Transport Safety Bureau and NSW Coroner are both conducting investigations into the fatal incident but the coroner in Reading, UK, officially opened an investigation on Monday.
Senior coroner Peter Bedford reportedly told the inquest Mr Cousins' fiancee, Emma Bowden, died of head injuries and drowning.
Her daughter, Heather, also died from head injuries and drowning.
Mr Cousins' eldest son William died from head and facial injuries while his youngest son, Edward, drowned.
"The New South Wales Coroner is currently leading an investigation into the deaths of those concerned involving many local authorities," Mr Bedford said, according to local media reports.
"This will be based on air traffic investigations led by the Australian Transport Safety Bureau and other specially trained people."
He proposed suspending the UK inquest pending the results of the NSW Coroner's reports.
"These people have specific expertise as well as, importantly, having access to the scene," he said.
Mr Bedford said he would then decide if it was appropriate to conduct his own formal inquest in Reading.