Hon. Justice Peter Mahon

On 7 July 1980 a Royal Commission of Inquiry into the Erebus disaster began. Presiding over the commission was Justice Mahon, a judge of the High Court of New Zealand. Justice Mahon was given 10 points of reference for his inquiries, the most significant of those being to determine whether any “culpable act” had led to the disaster – be that act committed by someone on board or on the ground.

The decision to hold a royal commission had been announced by Attorney-General Jim McLay in early March – before Ron Chippindale, the Chief Inspector of Air Accidents, had completed and released his report. Despite advice to the contrary, the New Zealand Government allowed the Chippindale report to be made public in early June. “Despite its careful catalogue of matters which might be contributing causes, it had very clearly placed the responsibility for the accident upon the aircrew.”1 Media outlets fuelled the public perception of an incompetent flight crew with headlines like: “CRASH REPORT POINTS TO ERROR BY DC10 CAPTAIN”, and “FLIGHT THOUSANDS OF FEET TOO LOW.”2

Also colouring the public mood were media claims that the final coordinates of the flight had been altered without the flight crew’s knowledge. In response to those claims, on 25 February 1980, Chief Executive Morrie Davis made the claim that “…the navigation information and flight plan for the aircraft which crashed was accurate and entirely in order”3.

It was within this environment, then, that Justice Mahon faced the challenge of identifying and objectively assessing all the possible origins of culpability for the disaster. The “Mahon Report”, as it came to be known, is the judge’s official summary of evidence presented to the commission, and his assessment of culpability as established by his analysis of that evidence. Mahon’s conclusions were very much different than those reached by the Chief Inspector – and they effectively cost him his career.

For the aviation layman, this document provides excellent explanations of a number of technical aspects of 1970s’ airline flying that sit at the core of this case. Justice Mahon, not an aviator, went to considerable lengths to ensure he had a solid understanding of:

The DC10’s navigational system (Paragraphs 78-97)

The DC10’s cockpit voice recorder (CVR) and the processes involved in arriving at a transcript (Paragraphs 98-124)

The process of planning for, and the legislation surrounding, new airline routes (Paragraphs 125-164)

The whiteout phenomenon (Paragraphs 60-201)

The alteration of the position of the McMurdo waypoint (Paragraphs 224-255)

A reading of these sections will provide anyone with an ample understanding of the key components of evidence provided. However, it is not Justice Mahon’s thorough technical explanations that make this an extraordinary document: it is his analysis and appraisal of who did what and why, both prior to the disaster and during the Commission of Inquiry.

Mahon is both fair and uncompromising in his analysis. For example, it is a generally held view that he essentially dismissed Chippindale’s efforts – but that is not accurate. Mahon acknowledges that the Chief Inspector faced a task that was “daunting in the extreme” (Paragraph 61), and that the constraints of the format under which he was required to report led to a misinterpretation of his conclusions by the general public (Paragraphs 67, 69-70).

Those considerations in mind, Mahon leaves no doubt as to his views on certain aspects of Chippindale’s conclusions, stating that the Chief Inspector’s finding that the crew were not misled by the error in flight plan was “untenable” (Paragraph 71); and that, “I find myself in disagreement with the Chief Inspector’s opinion… that the crew was ‘uncertain’ of its position.” (Paragraph 73).

Each of Justice Mahon’s opinions is sculpted by two primary forces: logic, and insightful analysis of the human condition. Every conclusion has at its base facts brought in evidence, but is moulded by Mahon’s direct, no-holds-barred assessment of the motivations of the storytellers. As a result, this document is in no way a “dry” read. Possibly the best known (and most controversial) example of his biting turn of phrase is contained near the end of the document under the section title “The Stance Adopted by the Airline Before the Commission of Inquiry”: “The palpably false sections of evidence which I heard could not have been the result of mistake, or faulty recollection. They originated, I am compelled to say, in a pre-determined plan of deception. They were very clearly part of an attempt to conceal a series of disastrous administrative blunders and so… I am forced reluctantly to say that I had to listen to an orchestrated litany of lies.” (Paragraph 377). It is the expression of such opinions that, ultimately, cost Justice Mahon his career.

The controversy of Justice Mahon’s opinions aside, his report is most notable for its groundbreaking allocation of culpability to organisational failure (Paragraph 393). This kind of conclusion was somewhat revolutionary in 1981, as identified in the chapter entitled “Erebus and Beyond” in the book Beyond Aviation Human Factors. When referring to accident investigation techniques used at the time of Erebus, the authors identify a “tendency for investigators to treat existing social and organisational activities as irrelevant ‘standing conditions’, and to reason backwards… [to] a point at which an individual failed to act in accordance with precedent, rule or regulation4… [T]his approach… end[s] with some residual and trivial category of human failure. The historical epithet ‘pilot error’ comes to mind in this context…” 5.

Justice Mahon – by investigating those “standing conditions” and naming them as a latent failure that contributed to the disaster – helped to shift the focus of accident investigation from apportioning blame to “identify[ing] those systemic failures which either foster and enable human error, or which fail to contain and negate its consequences” 6 . The far more worthy aim of this sort of accident investigation is to preclude a similar recurrence.

Readers are encouraged to make reference to this document in its entirety, and to take time to reflect upon its significance – not only in terms of when it was published, but its lasting effects on the field of risk management and organisational accident investigation. It takes only a moment’s contemplation to realise that most of us probably have some reason for which to offer our retrospective thanks to Justice Mahon and his Commission of Inquiry.