Australians have paid tribute to the three Royal New Zealand Air Force personnel, killed when their Iroquois helicopter crashed north of Wellington.

The three pilots were remembered as part of Anzac Day commemorations in Hobart, yesterday.

Australian Peacekeeper and Peacemaker Veterans' Association of Tasmania, Phil Pyke, said many Australians had served alongside Flight Lieutenant Hayden Peter Madsen, who was one of those killed yesterday.

Mr Pyke said Mr Madsen served in the Solomon Islands as operations officer for the for the aviation group as part of the Joint Task Force.

"We remember their families and Squadron members at this difficult time," Mr Pyke said.

Australia Prime Minister Kevin Rudd said he was deeply saddened by the deaths, the Australian newspaper reported.

"I extend, on behalf of the Australian government and people, our condolences to the families of the victims, to the service men and women of the New Zealand Defence Forces, and to the government and people of New Zealand."

Mr Rudd said the date of the accident compounded the helicopter tragedy.

"This tragedy is an especially poignant reminder of the risks that our men and women in uniform continually face on behalf of our two nations and for our freedoms," he said.

Flight Lieutenant Madsen, 33, Flying Officer Daniel Stephen Gregory. 28 and Corporal Benjamin Andrew Carson, 25, were all killed when the Iroquois crashed into the side of a mountain while on their way to take part in Anzac commemorations in Wellington.

Their bodies were found by an Air Force crewman who ran 2km through steep and rugged uphill terrain to get to the mangled helicopter wreck.

The man was on board one of three Iroquois helicopters flying in formation from Ohakea air base to Anzac Day services in Wellington, when another of the aircraft crashed in heavy cloud, killing the three men shortly before 6am yesterday.

Another crewman survived and was last night in a stable condition in Wellington Hospital.

Several investigations have started into the tragedy, which came on the day New Zealand remembered those who gave their lives for their country.

Air Vice-Marshal Graham Lintott, head of the Air Force, said: "Today we remember those who lost their lives doing their duty at Gallipoli 95 years ago and now we must add the names of three more who have lost their lives in the service of their country.

"They were all too young, and all with good futures to look forward to, and now we mourn their loss."

Last night, in Gallipoli, Prime Minister John Key paid personal tribute to the men who were killed, saying since he had become Prime Minister, he had come to know the camaraderie and the sense of family in the defence forces.

"You lost three friends today. Muddy, Dan and Ben. They were great young guys and had the world in front of them. You were proud of them and we were proud of them too."

The tussocky hills above Pukerua Bay where the accident happened were so shrouded in cloud that the other two helicopter crews initially did not know about the tragedy.

When the crews realised they had lost contact and returned to investigate, they had to land not far above sea level and send the crewman on foot to find the wreckage.

An emergency locator beacon in the crashed helicopter was triggered, giving the general location of the accident.

"None of us could get in to see," said Westpac rescue helicopter crewman Dave Greenberg of the Air Force man's dash.

"He was going to see if he could find wreckage or if they were okay. He didn't know what he was going to find.

"He was a real hero in my eyes. He did an amazing job. He probably ran the better part of 2km through some tough terrain."

Mr Greenberg said that when the cloud cleared soon after the rescue helicopter arrived, the man communicated with its crew using hand signals.

Defence Minister Wayne Mapp would not add to conjecture that the low cloud in the area was a likely factor in the crash, but said that would form part of the investigations.

Air Vice-Marshal Lintott said the weather was poor but "we fly in poor weather all the time".

He believed the crew had night vision goggles, but the investigation would determine whether they were being used.

Police search and rescue teams and specialist disaster victim identification team members were called to assist Air Force personnel who were also investigating the accident.

The survivor, who has leg and chest injuries and had not been named last night, was found about 25m from the wreck, wedged against bushes in a steep gully.

It was not known whether he was thrown clear or crawled there.

A Wellington Free Ambulance paramedic was winched down to retrieve him, and he was taken to Wellington Hospital where he was in a serious but stable condition last night.

Witnesses told of hearing a helicopter flying over what they said was a common flight path, and then silence.

Yvonne Clements, who lives on hills below the crash site, said she awoke to a "thud".

She got up and looked out the window and saw a thick fog and mist, told her husband that something had woken her up, and didn't think any more about it until she heard more helicopters 20 minutes later.

"I was asleep and I heard this big thud and it woke me up and I thought'goodness, what's that?'," she said. "It was just the thud when it must have hit."

Nearby residents Graham and Kathy McLauchlan could yesterday see the crash site in the fleeting moments that the mist and cloud moved away.

"It looks like a pancake," Mr McLauchlan said.

He said the couple often heard helicopters in the area.

"We're used to it and you hear them coming and you hear them build up and then pass and this one built up and then stopped and we knew that was a bit strange," he said.

"The question is what happened? They were heading south and they hit the south side of the hill. They've hit the wrong side of the hill."

Rescuers used a farm track to get 4WD vehicles to the wreckage, and removed the bodies.

Kapiti-Mana police area commander Inspector John Spence said about 20 people had been involved with the hillside rescue.

"It's a very poignant day for New Zealand ... Anzac Day, remembrance day, so especially for the armed services and especially the Air Force, it's a very difficult day."

- Beck Vass and NZHERALD STAFF