Mahan's investigation report was released on April 27th 198 1. This investigation report, an argument against the official investigation, cleared the pilot of his guilt. Mahan pointed out that the most important cause of the accident was that Air New Zealand unilaterally revised the flight plan of the flight without notifying the flight crew. According to the new flight plan, the plane will fly directly to Mount Erebus instead of flying over the volcano. Due to the white sky, the film crew failed to visually discover the volcano ahead. Moreover, the crew may face a rare natural phenomenon-sector whiteout, which makes the pilot see the distant horizon (it is estimated that there was a big gap between the clouds at that time, which can reflect the scenery behind and behind the Ross snow shed). Mahan also pointed out that the two pilots in charge of flying are both pilots with thousands of flying hours and rich experience, and they have some experience in the accuracy of inertial navigation systems in aircraft. Mahan also found that before the accident, McMurdo Station had approved the plane to descend to the altitude of 1500 feet (450 meters), which was far below the lower limit stipulated in the aforementioned flight safety regulations.
In paragraph 377 of Mahan's report, he accused airline management and senior pilots of conspiring to cover up the facts and deceiving investigators with "well-planned lies". Air New Zealand was very dissatisfied with Mahan's investigation report, so it appealed to the local court and won the case. Mahan therefore appealed to the Privy Council. On both appeals, Mahan's investigation into the cause of the accident-the ground crew did not inform the flight crew of the change in flight plan-was not questioned. Therefore, his conclusion that the accident was caused by the crew being misled to leave the original channel, rather than the pilot's mistake, was retained. However, the panel of judges of the Privy Council held that Mahan's statement in the investigation report accusing the management of Air New Zealand of conspiring to cover up the mistakes of the ground crew exceeded his power as an investigator and was not neutral. Therefore, 1982 101October 20th, the Privy Council upheld the judgment of the Court of Appeal and rejected Mahan's appeal.
In this regard, aviation researcher John King has such a description in his book "The Tragedy of New Zealand, Aviation": "
They (judges of the Privy Council) overturned Mahan's appeal one by one, including appendix 164, saying that "it cannot be used by any experienced pilot for navigation". On this basis, it is pointed out that there is no basis for a survey result in the report to accuse the CEO of an airline of planning cheating (accident investigator). "
Among them, Appendix 164 is a copy of the flight route map of the aircraft in McMurdo Bay. According to some public evidence, this picture was also included in the documents received by two pilots in the briefing on the passenger plane1979165438+1October 9. The picture shows two routes: one is the route to the south, passing through the west of Ross Island; The other is the northbound route, which passes through the eastern part of Ross Island. But there is no intersection between the two routes on the map, and the route map does not extend to the south, so it is impossible for the pilot to know where the routes meet from this map, in that way. Mahan also found from the official investigation report that chippendale knew little about the operation of jet planes. This is because he (and the New Zealand Aviation Authority to which he belongs) has been investigating the collision accidents of simple small planes and has no experience in investigating the air crashes of large planes like this one. Chippendale's investigation method is not rigorous, and there are some loopholes and data errors in his report. For this reason, chippendale ignored the temporary change of flight plan and the importance of the rare Antarctic climate phenomenon faced by pilots to the accident. To put it simply, the air crash could have been avoided if the pilot had known that the flight plan had been modified before taking off.