On 31 May 1980, six months after the accident, the Office of Air Accidents Investigation released Ron Chippindale’s report into the Erebus tragedy. The report, in standard format, includes the obligatory summary of facts, then the chief investigator’s analysis, conclusions, observations and recommendations. The appendices include a (later disputed) transcript of the 32 minutes of conversation available on the cockpit voice recorder (CVR), and a selection of maps and charts showing the aircraft’s planned and actual tracks, and photographs of the accident site.
Conclusions drawn from the vast majority of factual summaries give undisputed confirmation of the serviceability and performance of the aircraft systems and the crew. For example:
- Waypoint coordinates were entered into the navigation computer exactly as they were depicted on the printed flight plan, and the navigation system was functioning well within its accuracy limits: the aircraft was on track when it hit the mountain. (Refer paragraph 1.18.2)
- The ground proximity warning system (GPWS) had functioned exactly in accordance with its design. Furthermore, the crew’s reaction time was “established as very similar to or better than that of experienced crews placed in a similar situation in the training environment of the flight simulator.” (Refer paragraph 2.18)
Meteorological information confirmed that conditions at the time were conducive to the existence of surface whiteout in a VMC environment (clear of cloud with good visibility). However, what is evident from the report is Mr Chippindale’s lack of understanding of the impact of that phenomenon in the presence of the entire crew’s mindset regarding their position.
For readers unfamiliar with the details of the Erebus saga, it is important to highlight the fact that Justice Mahon’s subsequent Commission of Inquiry disagreed with Mr Chippindale’s findings in this accident report. Readers may find it useful to compare the coverage of the following issues between Mr Chippindale’s and Justice Mahon’s reports, as they contribute significantly to the vastly different conclusions drawn by the two men.
- The whiteout phenomenon. Chippindale makes the statement in paragraph 2.20 that the whiteout conditions made the snow slope appear to the pilots as “an area of limited visibility”. Justice Mahon’s coverage of the issue shows a far greater understanding of the illusion presented to the crew. (Refer paragraphs 165-201, and paragraphs 266-288)
- Minimum altitude for Antarctic flights being 16,000ft, or 6000ft south of McMurdo if specified visual meteorological conditions (VMC) existed. Mr Chippindale makes much of the captain’s decision to descend below these company-promulgated “absolute” minimum altitudes. Justice Mahon disputes the “absoluteness” of the minimums. An examination of paragraphs 202-223 of his report reveals that whilst Air New Zealand management claimed all Antarctic flights had observed the stated minimums, the majority had not. Furthermore, the company had advertised widely the wonderful views available from the “low-level” scenic flights. (Publicity efforts included the National Film Unit filming the low-level operations – refer MacFarlane book below).
- Changes made to the flight-plan coordinates without the flight-crew’s knowledge. Mr Chippindale acknowledges, in paragraph 2.5, the failure of Air New Zealand to notify the crew of the change to their flight plan from that on which they had been briefed, but goes on to make the astounding statement – later in the same paragraph – that “no evidence was found to suggest that they [the crew] had been mislead [sic] by this error”.
This issue forms the core of the causality argument advanced by Justice Mahon: the flight-planned track on which the crew had been briefed took them down the centre of McMurdo Sound. The flight plan with which they were provided on the day put them on a collision course with Mt Erebus at any altitude below 12,450ft.
The true course of events surrounding the changing of the flight-plan coordinates will only ever be known by those directly involved. Whilst Mr Chippindale pays scant attention to the reason for (or the consequences of) the error, paragraphs 224-255 of Justice Mahon’s report detail his attempts to untangle Air New Zealand’s obfuscation of those events. It is difficult reading, and one is left unable to disagree with the judge’s infamous “litany of lies” assessment.
- The CVR transcript. Mr Chippindale identifies from the version of the transcript appended to the report that the two flight engineers “expressed their mounting alarm as the approach continued” (paragraph 2.20), and cites the engineers’ comments again in paragraph 2.25 as evidence that there was an awareness amongst those on the flight deck that all was not well. Unfortunately, the media cited the presence of anxiety on the flight deck as evidence of irresponsible aviating by Captain Collins. A much different view – one more cognisant of many more aspects of the bigger picture – is arrived at by Justice Mahon (paragraphs 98-124).
Mr Chippindale brings up several other issues – such as the lack of polar survival equipment on board, and the fact that the pilots altered their altimeter settings to local QNH (pressure setting) much later than they should have on descent – but, in the main, these proved inconsequential when deciding upon the accident’s root cause, which he attributed to the “captain’s decision to make a VMC descent below the specified minimum safety height while north of McMurdo.” (Paragraph 2.1)
The controversy caused by this conclusion led to the Royal Commission of Inquiry, and its much different assessment of the true cause. Readers are encouraged to consult Justice Mahon’s document in its entirety, as well as Stuart Macfarlane’s weighty tome The Erebus Papers (Avon Press Ltd, 1991) to gain a broader perspective on the accident’s context and causes.