A very interesting discussion. I suspect the main reason why this debate still rages is that Justice Mahon completely exonerated the crew. In apportioning blame, it wasn't "90% Airline / 10% Crew". It was "100% Airline / 0% Crew". And as has already been pointed out, that finding was not affected by the subsequent litigation, which focused on other unrelated issues. So history will record that the crew was completely blameless, and this is difficult to accept. The airline, obviously, must shoulder most of the responsibility. But Mahon's complete exoneration of the crew, and the methods he used to get there, are very difficult to understand.
It should be noted Mahon was a lawyer, not an aviator - and he was not above the twisting of a word or two. The end result sounds good on the first reading, but makes less sense on subsequent readings. The classic example is the way he dealt with Chippendale's finding that the crew descended below Minimum Safe Altitude when "unsure" of their position. Mahon seized on the word "unsure", and found that the crew were, in fact, sure of their position: they believed they were in McMurdo Sound. But how can this form any basis for exonerating the crew? If they believed they were in McMurdo Sound, they were wrong. And the surer they were, the wronger they were.
As to the crew's certainty of their position, there is one piece of evidence that is never referred to. Just before the Ground Proximity Warning System sounded, the captain said "We're 26 miles north. We'll have to climb out of this." The first officer, seated in the right-hand seat, says "It's clear to the right and ahead. You're clear to turn right. There's no high ground if you do a 180." The captain responds "No. Negative." At this point, the GPWS sounds, the captain calls for go-around power and there is a sudden manual application of LEFT rudder.
No-one, including Mahon (who never referred to this evidence), has explained why a pilot who is certain he is in the centre of McMurdo Sound would decide to turn left to climb out, because Erebus and Mount Bird would be to the left. The obvious manouvre was the right turn that had been expressly suggested by the first officer. The first officer, of course, was wrong. A right turn would have produced a collision with the cloud-covered Mount Bird - and the captain, in the final seconds of the flight, appeared to have some appreciation of there being danger to the right. And when the GPWS sounds, there is an immediate attempt to climb out, rather than any reference the possibility of a false alarm. None of this is consistent with the crew being certain that they were in McMurdo Sound.
Beaufort Island
Judge Harold Greene commented that the crew "missed the obvious landmark of Beaufort Island being on the wrong side of the flightpath."
Mahon attempted to explain that failure, but I did not find his explanation particularly convincing. Of more significance, in my mind, is a photograph of Beaufort Island that was included in Mahon's report. The photograph was taken by a passenger on the flight, and was included for the purpose of demonstrating that the aircraft was flying in clear air. But the photograph also demonstrates that Beaufort Island was almost impossible to miss. The photograph shows an island of significant size, with high cliffs. It is difficult to accept that the crew did not see the island, especially given that they flew past it on three occasions, two of which were below the cloud base. And it appears from the transcript that Beaufort Island was, in fact, sighted from the flightdeck. The Chippendale Report contains a diagram with the track plotted in 3D against the terrain. Also included are comments from the transcript, which are plotted on the track. As the aircraft is half-way through the second of its descending orbits, and just at the point when Beaufort Island is dead ahead, the flight commentatator says "There you go. There's some land ahead."
The flight commentator was not part of the crew, but given that he had just identified some land ahead, wouldn't the next question be "What land is that?" The aircraft had been relying on instruments alone since leaving Auckland, was approaching Antarctica, was flying VMC, below MSA, and the flight commentator had identified land ahead. I would have thought that at least one member of the crew would have attempted to cross-check the assumed poisition against this topographic feature. Had that been done, it would have been obvious that the assumed position was wrong. The map would have shown that there were no other islands in the vicinity. The island ahead could not have been any island other than Beaufort Island and the track allegedly plotted on the atlas would have showbn that the aircraft was on the wrong side of Beaufort Island, on a collision course with Erebus.
Change of the Waypoint
I note the explanation of "Desert Dingo" for the change to the waypoint. This appears to follow Mahon's theory, which was that the Navigation Section of the airline was attempting to conceal something from the US authorities or/and the Department of Civil Aviation. But what were they supposed to be trying to cover up? Mahon seemed to believe that the staff at the Navigation Section devoted large amounts of time towards some bizarre conspiracy, when all they had to do was simply change the route to what they wanted and then have it appoved by the US authorities and by Civil Aviation. I much prefer the evidence of the Navigation Section, who frankly admitted that they made a series of errors.
Putting the conspiracy theory to one side, it is not disputed that the nav track for the initial flights was over Erebus. It is not disputed that nav truck for later flights was down McMurdo Sound. And it is not disputed that on the morning of the fatal flight, the nav track was changed, back to one going over Erebus. Desert Dingo does not discuss the circumstances that led up to this final change. Mahon goes into the issue is some depth, but in doing so, he raises an important question which he never answers.
Approximately two weeks before the fatal flight, another flight had visited Antarctica. Shortly after this flight, the captain spoke with the airline executive pilot responsible for navigation on the Antartic flights. The discussion concerned the final waypoint. (It should be noted that on this flight, unlike the fatal flight, the final waypoint was in the centre of McMurdo Sound, which produced a nav track down the sound, rather than over Erebus.) Conflicting evidence was given about the discussion. The executive pilot said that the captain told him that the waypoint was in the wrong position. The executive pilot, assuming the correct track to be over Erebus, instructed the Navigation Section to correct the error, which they did on the morning of the fatal flight. The executive pilot's evidence was hotly contested. The captain said that he never told the executive pilot that the waypoint was in the wrong position. All that was said, according to the captain, was that when he overflew the waypoint in McMurdo Sound, he was about 20km from where he thought he would be and that he believed that future crews should be told of this.
Mahon accepted the captain's evidence, and rejected that of the executive pilot. In doing so, Mahon refused to accept that an airline would "program" an aircraft to fly over an active volcanoe. Again, this sounds good on the first reading, but makes less sense the more you think about it. The purpose of the nav track was to get the aircraft to the vicinity. It seems perfectly reasonable to align the nav track with the most conspicuous topographical feature, specifying a minimum safe altitude. Once in the vicinity, the aircraft was not committed to its nav track.
Even if the captain's evidence is accepted, it is very difficult to understand. The reason is that the captain attended the same briefing as Captain Collins. The briefing officer gave evidence and said that he told the pilots that the nav track went over Erebus. At that time, the nav track did not go over Erebus, but the significance of the briefing officer's evidence is that the pilots at the briefing were told that it did, and that one of those pilots was the captain on the fatal flight. The briefing officer's evidence was disputed by the captain, who was admanant that there was no reference to the nav track going over Erebus.
The important question that arises from that evidence is this: If the captain believed that the nav track was down McMurdo Sound, rather than over Erebus, why, when he overflew the waypoint in McMurdo Sound, did he note anything unusual? Why, in fact, did he note anything at all? If his evidence about the briefing was correct, the waypoint was exactly where it was supposed to be. If, on the other hand, the briefing officer had told the captain that the nav track went over Erebus, then there would be something unusual to note when the captain overflew the waypoint.
There may be an explanation for this, but Mahon never gave it. Instead, he labelled the executive pilot and the briefing officer as perjurers. This apparent contradiction goes right to the heart of the matter, because if the briefing officer told the pilots that the nav track went over Erebus, it is no answer to say that a sheet of paper was handed out with co-ordinates which, when plotted on a domestic atlas, showed a track down McMurdo Sound. In that situation, the pilots attending the briefing were obliged to clarify the situation.