Mission To Recover Missing Helicopter Continues Despite Intense Winds

The search continues for a pilot and four passengers who are feared dead after a helicopter crashed into waters off the NSW coast, with authorities seeking out witnesses who could have seen the aircraft in distress.

Police are spearheading the recovery operation after the Bell UH1 helicopter dropped off the radar near Anna Bay, north of Newcastle, early on Friday night.

The aircraft belonged to Brisbane Helicopters owner and pilot David Kerr, who is believed to have been flying it at the time.

Queenslanders Jamie Ogden and Grant Kuhnemann and NSW couple Jocelyn Villanueva and Gregory Miller are also believed to have been on board.

NSW Police has called for anyone who may have seen the helicopter in distress, and anyone who filmed or photographed the aircraft on Friday night to come forward.

READ MORE: Search For Missing Helicopter Suspended After Wreckage Spotted

The Australian Defence Force on Sunday confirmed Mr Miller was an employee but said he was not on duty at the time of the crash.

The force is engaging with authorities to help with recovery efforts, a spokesperson told AAP in a statement on Sunday.

Mr Ogden's brother Darren has flown to Nelson Bay from Queensland after hearing about the crash.

"I'd rather be here, there's not much I can do at home so I'd rather be here and if I can help in any way I can and just be there if they ever find a body," Darren told 10 News First on Sunday.

"He's just so full of life and he just helped everyone," Darren said of his brother.

The search for five people continues. Photo: Twitter/ Marina Neil.

The Australian Transport Safety Bureau is investigating, with officers from Canberra travelling to the area to examine the recovered wreckage, interview witnesses and inspect aircraft and pilot records.

The bureau on Sunday also called for any witnesses who may have seen the helicopter to contact them as they investigate the circumstances of the crash.

"Witness reports can help provide invaluable information to ATSB investigators as they begin the task of determining the circumstances of this tragic accident," the bureau said on Facebook.

"The ATSB expresses its deepest sympathies to the families and friends of those on board the helicopter."

The Australian Maritime Safety Authority said the helicopter had been on a private flight between Coffs Harbour and Bankstown in Sydney's southwest.

Anna Bay. Image: Google

It launched the search for the aircraft on Friday night and spotted an oil slick and several pieces of debris.

Most of the wreckage was uncovered on Saturday, with the helicopter's tail rotor found by water police about 8.45am.

A 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 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.

Civil Aviation Safety Authority records show the 1960s US military helicopter - famously known as a "Huey" - was registered for use by Brisbane Helicopters in October last year.