Home > Kiwi Heroes > Peter Thomas Mahon, QC (1923 – 1986)

Peter Thomas Mahon, QC (1923 – 1986)


“Peter Thomas Mahon was a New Zealand High Court Judge, best known for his Commission of Inquiry into the crash of Air New Zealand Flight 901 (“Mount Erebus disaster”). His son, Sam Mahon is a well-known artist.

Mahon began his legal career with the Raymond, Donnelly & Co. He was mentored by Sir Arthur Donnelly. Mahon was junior counsel for the prosecution in the Parker-Hulme murder case in 1954.

After the crash of Air New Zealand Flight 901 with loss of all aboard on 28 November 1979, an accident report was released by the chief inspector of air accidents, Ron Chippindale, which cited pilot error as the chief cause of the accident. Public demand led to the formation of a Royal Commission of Inquiry into the accident, consisting solely of Mahon. He produced his report on 27 April 1981, which cleared the crew of blame for the disaster and found that the major cause was the reprogramming of the aircraft’s navigation computer without the crew being notified. Mahon controversially claimed that Air New Zealand executives engaged in a conspiracy to whitewash the inquiry, covering up evidence and lying to investigators, famously accusing them of “an orchestrated litany of lies”. His book, Verdict on Erebus, an account of his inquiry, won the New Zealand Book Awards prize for non fiction in 1985.



Mahon retired from the High Court bench in 1982.

In 1983 the Judicial Committee of the Privy Council held that Mahon had acted in excess of his jurisdiction and in breach of natural justice by going on to make findings of a conspiracy by Air New Zealand to cover up the errors of the ground staff.

In 1985 Mahon was appointed as Commissioner of Inquiry into the 1984 Queen Street riot. In the same year he published “Dear Sam”, a collection of his letters to his children.

In 2008, Mahon was posthumously awarded the Jim Collins Memorial Award by the New Zealand Airline Pilots Association for exceptional contributions to air safety, “in forever changing the general approach used in transport accidents investigations world wide.”” – Source
“Justice Peter Mahon accused Air New Zealand of an “orchestrated litany of lies” in his finding on the cause of the crash of the DC10 aircraft on Mt Erebus on November 29, 1979, which killed all 257 passengers and crew.

In his report released in 1981 he said DC10 pilot Jim Collins was not told of a last-minute change to the flight path co-ordinates, and neither he, First Officer Greg Cassin, nor the flight engineers, made any error which contributed to the disaster during a sight-seeing flight.

Air NZ challenged Justice Mahon’s accusation of a “predetermined plan of deception” and the Court of Appeal overturned the finding, saying the judge had exceeded his terms of reference.

Justice Mahon resigned, and died in 1986 but his comments echoed around the world.

Now the New Zealand Airline Pilots Association (ALPA) said it would posthumously present Justice Mahon with the Jim Collins Memorial Award for exceptional contributions to air safety.

“It is for his sterling work, in forever changing the general approach used in transport accidents investigations world wide,” said ALPA executive director Rick Mirkin. ” – Source

“The one-man commission, the late Justice Peter Mahon, was slammed by Muldoon who refused to table his 1981 report which accused Air New Zealand witnesses of participating in an “orchestrated litany of lies” on the witness stand…

… Justice Mahon found a navigation computer had been incorrectly changed so the plane was programmed to fly into the mountain, and that Air New Zealand witnesses had lied to cover up other mistakes that pointed blame at the carrier.

Muldoon responded with venom – the findings were potentially fatal to the Government-owned carrier – while Air New Zealand prepared an appeal against the lying accusations in court.” – Source

“… Successive governments refused, year after year, to officially recognise Justice Mahon’s accident report which overturned the assertions, made by the Chief Inspector of Air Accidents Ron Chippindale, that the pilots were culpable. With unassailable logic, Mahon proved him wrong. Justice Mahon’s report was eventually tabled in Parliament and became an official document in mid 1999, thanks to the efforts of Hon Maurice Williamson.

“That report absolutely clears the pilots of any blame. Yet confusion about what caused the accident remains in the minds of New Zealanders. It was to the advantage of many men in government, in Civil Aviation and in the airline that this confusion reigned for so long… ”

When the plane crashed, Captain Jim Collins left behind a wife and four young daughters. As well as examining the technical arguments around the cause of the crash, the book looks at the intensely personal impact the tragedy had on them…

Speaking on behalf of the family, Kathryn Carter, who was 15 at the time of the crash, says, “Our father and his co-pilot, Greg Cassin, were cleared of all blame by the Royal Commission. We want that to be understood and accepted by Parliament once and for all, and for it to be accurately recorded for New Zealand’s history.”” – Source


Justice Peter Mahon. He arrived at the truth surrounding the Erebus Crash in 1979 – but it was an Inconvenient Truth, and it upset many powerful people in high places. The highest, it might be said, was the authoritarian Prime Minister of the day, Robert Muldoon.

Armed with nothing but his integrity and the truth he had uncovered, Justice Mahon stood against them all. I believe he will be remembered as one of New Zealand’s finest, most heroic people.

R.I.P. Peter Mahon, for you were an Honourable Man.



  1. 4 January 2012 at 2:40 am

    Mahon was a man’s man like Temm and Thomas- unlike so many others in the judicial club who abuse their fiduciary obligations like out of control drunks.

  2. 4 January 2012 at 9:39 am

    Christopher Wingate :

    Mahon was a man’s man like Temm and Thomas- unlike so many others in the judicial club who abuse their fiduciary obligations like out of control drunks.

    He certainly called it like it was, Christopher. His comment “litany of lies” is one now firmly embedded in our history, and is now synonymous with straight-talking. Especially when one rarely expects it from “The Establishment”.

  3. D. Mitchell
    1 February 2012 at 11:50 pm

    Mahon’s “litany of lies” comment was the result a bizarre conspiracy theory.

    As for his findings as to the cause of the accident, check the various aviation websites (eg Aviation.Net, PPrune). He got it comptetely wrong.

  4. Simon Sweet
    24 December 2014 at 11:39 am

    Mahon’s “litany of lies” comment was the result a bizarre conspiracy theory.

    As for his findings as to the cause of the accident, check the various aviation websites (eg Aviation.Net, PPrune). He got it comptetely wrong.

    The Erebus tragedy has been a passion on mine since 1988 , I have read every scrap of evidence available, Mahon came to the only logical conclusion. It is clear that some of the executives at Air NZ attempted to conceal their knowledge of `low flying` from the commission, probably to distance themselves from the tragic results that resulted from their laxness regarding `safe minimum altitude`.
    There was a conspiracy of `events` which by themselves would not have lead to the disaster but together made the accident more likely. Namely the airlines` acceptance of low flying “past“ Mt Erebus. (This had been noted in the company’s brochure prior to the accident.), was common knowledge within the industry and executives has been present on flights when this had taken place.. This accompanied with `whiteout` and the ineffectiveness of the ground proximity warning over ice and the reprogramming of the flight computer to fly directly AT Mt Erebus (while failing to tell the pilots)………What conclusion would you like to come to…read the evidence….

    • 24 December 2014 at 11:16 pm

      I would tend to agree 100% with you, Simon. I was a young adult at the time and followed events closely during the inquiry. It seemed obvious that the execs were lying their heads off to cover their backsides…

  5. Tim Fidler
    26 November 2018 at 7:16 pm

    What is really disturbing is that even thought 257 people died, nobody at air nz was bought to book in the defendant’s stand in a Nz court as culpable. It was as if ROb Muldoon said to Air nz..” you make the worst case retire with a golden handshake and I will make sure the police don’t start a prosecution “. Not only could it happen , it did happen. EVEN WORSE if yo look up ROn Chippendale on Wiki, it appears in 2008 He got a medal, this corrupt lying son of a bitch who was criticised by Mahan, J for lying and being incompetent… for is assistance to the Erebus enquiry and recovery operation. What a joke. The NZ govt must think we are all mugs. An award from the Nz governmet is utterly worthless as it is Corrupt.

    • 26 November 2018 at 11:33 pm

      I remember some of it, Tim, in my youth. Even as a naive 20-something-year old, I pickled up that something dodgy was going on. Peter Mahon’s reference to a “litany of lies” from Air New Zealand executives is still strong in my memory.

      Who knows, hopefully one day the full story may come out…

  1. 30 May 2017 at 12:02 pm

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