Authorities are expected to use a floating crane to recover a seaplane that crashed into a river north of Sydney on New Year's Eve, killing all six people aboard.
NSW police will attempt to recover the Sydney Seaplanes DHC-2 Beaver from the Hawkesbury River on Thursday in an operation that's expected to start at dawn and run into the afternoon.
Experienced pilot Gareth Morgan died along with high-profile UK businessman Richard Cousins, his two adult sons Edward and William, his fiancee Emma Bowden and her 11-year-old daughter Heather when the plane plunged into Jerusalem Bay on December 31.
The plane is resting on its roof in about 15 metres of water, according to All Waterfront Constructions operations director Chris Kemp, who will work to recover the aircraft.
Two slings will be lowered and passed through the aircraft's cabin by police divers, Mr Kemp told AAP.
"Then we'll be lifting the whole lot up and placing it on the barge," he said.
"One of the wings is pretty badly damaged and bent over on the plane itself, so we'll be pulling that back down and lashing it to the plane," Mr Kemp said.
"We were on it the other day with the police divers and the cameras and it looks like there is still a wing intact on the fuselage."
The Australian Transport Safety Bureau is working to determine why the seaplane went down. One possibility is the plane stalled.
Aircraft maintenance engineer Michael Greenhill told AAP on Wednesday that while it was not mandatory in Australia for Beaver planes to have stall warnings installed, most did.
"A stall is when the airflow over the aircraft's wing becomes insufficient enough to produce lift," Mr Greenhill said.
"So basically the wing stops flying."
A Canadian report, published in September 2017, recommended the warning system be mandatory on all Beavers.
Mr Greenhill has flown in the plane that crashed on New Year's Eve. He couldn't remember if it had the warning system installed but said it may not have helped in any case.
"Even if the Beaver had this system fitted there's a large possibility there would have been insufficient time to rectify the situation due to the low altitude and approaching terrain."
The wreckage of the plane is expected to be recovered about midday on Thursday before being taken to a reserve in Bayview.
The ATSB is investigating witnesses' claims the plane made a right-hand turn before it fell into the water.