Five people are feared dead in a helicopter crash, after some of the chopper's wreckage was spotted sinking off the coast of NSW.
Police were searching on Saturday for four men and a woman who were inside the Bell UH1 when it dropped off the radar near Anna Bay, north of Newcastle, at about 6.30pm on Friday.
But rough conditions put the hunt on hold, making it too dangerous for divers to enter the water.
The aircraft belonged to Brisbane Helicopters owner and pilot David Kerr, who is believed to have been flying the aircraft when it disappeared.
Civil Aviation Safety Authority records show the 1960s US military helicopter - famously known as a "Huey" - was registered for use by the Brisbane company in October last year.
The Australian Maritime Safety Authority understands the helicopter had been on a private flight between Coffs Harbour and Bankstown.
The authority launched a search for the helicopter on Friday night, spotting an oil slick and several pieces of debris they couldn't recover due to bad weather.
More of the wreckage was uncovered on Saturday, with the helicopter's tail rotor found by water police about 8.45am.
The Westpac rescue helicopter spotted the main airframe of the aircraft less than an hour later, roughly eight kilometres south of Fingal Bay.
They watched as it sunk before boats could retrieve it. The location was consistent with where the aircraft is believed to have entered the water.
"There have been no sightings of the occupants of the helicopter," AMSA said in a statement.
At midday, the search and rescue effort was suspended due to expert medical advice and the discovery of the damaged airframe.
NSW Police is now leading efforts to recover the sunken wreckage, which suffered a setback on Saturday afternoon when poor weather made it too dangerous for divers to enter the water.
NSW Police hopes to resume the effort at first light on Sunday morning, a police spokeswoman told AAP.
The aircraft went missing amid poor conditions with low visibility, high winds and dust in the air.
Air traffic control indicated the aircraft was rapidly losing altitude when contact was lost, and there were no emergency beacons signals or mayday calls detected.
