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قراءة كتاب Judgments of the Court of Appeal of New Zealand on Proceedings to Review Aspects of the Report of the Royal Commission of Inquiry into the Mount Erebus Aircraft Disaster C.A. 95/81
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Judgments of the Court of Appeal of New Zealand on Proceedings to Review Aspects of the Report of the Royal Commission of Inquiry into the Mount Erebus Aircraft Disaster C.A. 95/81
touching down en route. The southernmost point of the route, at which the aircraft turned round, was to be at about the latitude of the two scientific bases, Scott Base (New Zealand) and McMurdo Station (United States), which lie about two miles apart, south of Ross Island. On Ross Island there are four volcanic mountains, the highest being Mount Erebus, about 12,450 feet. To the west of Ross Island is McMurdo Sound, about 40 miles long by 32 miles wide at the widest point and covered by ice for most of the year.
It was originally intended that the flight route south would be over Ross Island at a minimum of 16,000 feet. From October 1977, with the approval of the Civil Aviation Division, descent was permitted south of the Island to not lower than 6000 feet, subject to certain conditions concerning weather and other matters. However, the evidence is that the pilots were in practice left with a discretion to diverge from these route and height limitations in visual meteorological conditions; and they commonly did so, flying down McMurdo Sound and at times at levels lower than even 6000 feet. This had advantages both for sightseeing and also for radio and radar contact with McMurdo Station. Moreover from 1978 the flight plan, recording the various waypoints, stored in the Air New Zealand ground computer at Auckland actually showed the longitude of the southernmost waypoint as 164° 48' east, a point in the Sound approximately 25 miles to the west of McMurdo Station.
The evidence of the member of the airline's navigation section who typed the figures into the computer was that he must have mistakenly
typed 164° 48' instead of 166° 48' and failed to notice the error. Shortly before the fatal flight the navigation section became aware that there was some error, although their evidence was that they understood it to be only a matter of 10 minutes of longitude. In the ground computer the entry was altered to 166° 58' east, and this entry was among the many in the flight plan handed over to the crew for that flight for typing into the computerised device (AINS) on board the aircraft. The change was not expressly drawn to the attention of the crew. The AINS enables the pilot to fly automatically on the computer course ('nav' track) at such times as he wishes.
The crash occurred at 12.50 pm on 28 November 1979. The aircraft struck the northern slopes of Mount Erebus, only about 1500 feet above sea level. There were no survivors. The evidence indicates that the weather was fine but overcast and that the plane had descended below the cloud base and was flying in clear air. The pilot, Captain Collins, had not been to the Antarctic before, and of the other four members of the flight crew only one, a flight engineer, had done so. The plane was on nav track.
The Chief Inspector of Air Accidents, Mr R. Chippindale, carried out an investigation and made a report to the Minister, dated 31 May 1980, under reg. 16 of the Civil Aviation (Accident Investigation) Regulations 1978. It was approved by the Minister for release as a public document. The Chief Inspector concluded that 'The probable cause of the accident was the decision of the captain to continue the flight at low level toward an area of poor surface and horizon definition when the crew was not certain of their position and the subsequent inability to detect the rising terrain which intercepted the aircraft's flight path'. He adhered to this in evidence before the subsequent Royal Commission.
The Royal Commission was appointed on 11 June 1980 to inquire into 'the causes and circumstances of the crash', an expression which was elaborated in terms of reference consisting of paragraphs (a) to (j). Mr. Justice Mahon was appointed sole Commissioner. In his report, transmitted to the Governor-General by letter dated 16 April 1981 and subsequently presented to the House of Representatives by Command of His Excellency and later printed for public sale, the Commissioner found that '... the single dominant and effective cause of the disaster was the mistake made by those airline officials who programmed the aircraft to fly directly at Mt. Erebus and omitted to tell the aircrew'. He exonerated the crew from any error contributing to the disaster.
The Commissioner and the Chief Inspector were at one in concluding that the crash has occurred in a whiteout. The Commissioner gave this vivid reconstruction in the course of para. 40 of his report:
I have already made it clear that the aircraft struck the lower slopes of Mt. Erebus whilst flying in clear air. The DC10 was at the time flying under a total cloud cover which extended forward until it met the mountain-side at an altitude of somewhere between 2000 and 2500 feet. The position of the sun at the time of impact was directly behind the aircraft, being in a position approximately to the true north of the mountain and shining at an inclination of 34°. The co-existence of these factors produced without doubt the classic 'whiteout' phenomenon which occurs from time to time in polar regions, or in any terrain totally covered by snow. Very extensive evidence was received by the Commission as to the occurrence and the consequences of this weather phenomenon. So long as the view ahead from the flight deck of an aircraft flying over snow under a solid overcast does not exhibit any
rock, or tree, or other landmark which can offer a guide as to sloping or uneven ground, then the snow-covered terrain ahead of the aircraft will invariably appear to be flat. Slopes and ridges will disappear. The line of vision from the flight deck towards the horizon (if there is one) will actually portray a white even expanse which is uniformly level.
What this air crew saw ahead of them as the aircraft levelled out at 3000 feet and then later at 1500 feet was a long vista of flat snow-covered terrain, extending ahead for miles. Similarly, the roof of the solid overcast extended forward for miles. In the far distance the flat white terrain would either have appeared to have reached the horizon many miles away or, more probably, merged imperceptibly with the overhead cloud thus producing no horizon at all. What the crew could see, therefore, was what appeared to be the distant stretch of flat white ground representing the flat long corridor of McMurdo Sound. In reality the flat ground ahead proceeded for only about 6 miles before it intercepted the low ice cliff which marked the commencement of the icy slope leading upwards to the mountain, and at that point the uniform white surface of the mountain slope proceeded upwards, first at an angle of 13°, and then with a gradually increasing upward angle as it merged with the ceiling of the cloud overhead. The only feature of the forward terrain which was not totally white consisted of two small and shallow strips of black rock at the very bottom of the ice cliff, and these could probably not be seen from the flight deck seats owing to the nose-up attitude of 5° at which the aircraft was travelling, or they were mistaken for thin strips of sea previously observed by the crew as separating blocks of pack ice.
The aircraft had thus encountered, at a fateful coincidence in time, the insidious and unidentifiable terrain deception of a classic whiteout situation. They had encountered that type of visual illusion which makes rising white plateaux appear perfectly flat. This freak of polar weather is known and feared by every polar flier. In some Arctic regions in the Canadian and in the north European winter, it is responsible for numbers of light aircraft crashes every year. Aircraft fly, in clear air, directly into hills and mountains. But neither Captain Collins nor First Officer Cassin had ever flown at low altitude in polar regions before. Even Mr Mulgrew [the commentator for the passengers], with his antarctic experience, was completely deceived. The fact that not one of the five persons on the flight deck ever identified the rising terrain confirms the totality of this weird and dangerous