30 years on from the Erebus tragedy, a leading aviation historian says the question of 'why' still remains and it is clear the Erebus disaster is still as real and as controversial as it ever has been.

Richard Waugh says between the Chippendale report, the Royal Commission of Inquiry, the Mahon report and Captain Gordon Vette's research, Erebus is one of the best documented tragic aircraft accidents in history.

Reverend Waugh says the question remains, how did a modern, beautiful airline go into a mountain. He says a lack of an answer is not for want of material, it is a case of where you end up on the spectrum of whether it was crew error, the airline or other factors which came together on that day.

Reverend Waugh says from a historical perspective, all the reports together suggest the accident was not quite as simple as Mr Chippendale thought it was. He adds that the commemorative sculpture at Air New Zealand's head office does not really cut it and we should have something which has inscribed on it the names of all 257 victims.

The 30th anniversary of Erebus in which an Air New Zealand sightseeing flight crashed into Mt Erebus, has meanwhile been marked with ceremonies in Antarctica, Auckland and Christchurch today.

In west Auckland a service was held where 54 of the victims are buried at Waikumete Cemetery in Glen Eden, seven others were cremated there.

Cemetery manager Daniel Sales says the ceremony was led by the Reverend Fred Holloway, and speeches were made by mayor Bob Harvey and Air New Zealand chairman John Palmer.

"We just want people to think that we never forget, we never forget, and the memorial's are here for eternity and we will never forget such an awful tragedy which really just touched the whole nation."

A service was also held on the Antarctic ice at Scott Base to mark the Erebus tragedy. About 50 people attended, including Air New Zealand executives, relatives of victims, staff from Scott Base and McMurdo, and board members from Antarctica New Zealand.

Air New Zealand's general manager operations, Dave Morgan, said the airline made mistakes and let down people directly affected by the tragedy. He said that weighs heavily on current management, and he repeated the airline's apology already made a month ago. He said sorry to those who lost a loved one, and those who did not receive compassion and support.

A hymn was sung and tears were shed during the service, and there was much hugging and embracing when it finished.

Moving words were spoken at the memorial for the Mt Erebus and Perpignan tragedies in Christchurch this morning. The memorial, held in an Air New Zealand hangar at Christchurch airport, coincided with the memorial at Scott Base in Antarctica.

Reverend Lynda Patterson from Christchurch Cathedral led the service and spoke of the pain felt by all New Zealanders. She said the loss of 257 lives on Mt Erebus is stamped on the national consciousness, and left very few lives untouched.

Reverend Patterson said lives were irrevocably changed by the two tragedies.

The only broadcaster to cover the Erebus tragedy in Antarctica says Air New Zealand covered its tracks immediately after the crash.

John Blumsky says Air New Zealand staff knew it was incorrect coordinates that caused the crash but took steps to protect the company. He says staff at head office shredded documents which in their opinion were not relevant to any future enquiries.

Mr Blumsky says concern over insurance claims motivated these actions.