A major air and sea search operation has been suspended off the New South Wales coast after an aircraft disappeared in destructive winds.
Four men and a woman are feared dead after the wreckage of a helicopter that faded off the radar overnight was seen sinking off the New South Wales coast on Saturday morning.
The privately owned Bell UH1 helicopter went missing in rough winds and storms at about 6.30pm on Friday off Anna Bay near Newcastle.
An observer on-board one of the rescue helicopters watched the wreckage sink a short time before boats arrived.
"The location of the airframe is consistent with the drift model of where the aircraft was believed to have entered the water," the AMSA statement said.
"There have been no sightings of the occupants of the helicopter."
The AMSA suspended its search based on "expert medical advice and the discovery of the damaged airframe", but police told news.com.au its divers are still at the scene trying to recover the sunken wreckage.
"AMSA would like to thank all the agencies involved in this rescue in extremely challenging conditions and extends our deep sympathies to the family and friends of those aboard the helicopter," the authority said.
The authority revealed the missing aircraft was rapidly losing altitude before it was reported as "fading off the radar", according to air traffic control.
Australian Maritime Safety Authority (AMSA) told news.com.au there had been multiple sightings of oil and debris from the air on Saturday morning but rough seas have made it impossible to access the area.
In blustery conditions, a Westpac chopper used night vision goggles and located "some wreckage" off Anna Bay, a spokesperson said on Saturday.
"Due to the conditions the helicopter returned to Belmont base and an Australia Maritime Safety Authority fixed-wing search and rescue aircraft from Essendon continued the search throughout the night," Glen Ramplin said in a statement.
Police also said wreckage had been spotted at Fingal Head but it was unable to be recovered.
Reports indicate four people were missing but it was confirmed there were four men and a woman on-board.
The missing chopper, VH-UVC, has distinct markings to be used as a US Army helicopter in films, The Daily Telegraph reported.
The publication also reported the aircraft was travelling at about 70 knots and 3500ft before falling at 154 knots, according to a flight tracking website.
A severe weather warning had been issued in the area last night with peak winds predicted to be in excess of 125km/h.
Three rescue helicopters, the AMSA jet and numerous boats are continuing to search on Saturday.
The joint operation with police is searching a 150 nautical mile area of sea 1km to the south east of Anna Bay.
The search party includes three helicopters, a plane and a water vessel.
The Westpac Rescue Helicopter was initially involved in the search party but was forced to return to its base due to the destructive winds.
It rejoined the AMSA and police when the search resumed at 7am on Saturday.
It was reported the private aircraft had travelled to Coffs Harbour from Brisbane to refuel before taking off towards Bankstown Airport when it disappeared.
Anyone with information is urged to call triple-0.