Reasons for rejecting claims of pilot error

Press, 30 April 1981, Page 4

Reasons for rejecting claims of pilot error

Glossary

VMC: Visual meteorological conditions. CVR: Cockpit voice recorder. NAV TRACK: Programmed flight path. AINS: Area Inertial Navigation System. DME: Distance measuring equipment. MSA: Minimum safe altitude. ICE TOWER: McMurdo control tower. TACAN: Tactical air navigation system. HSI: Horizontal situation indicator.

'ine total exoneration of the air crew of the Air New Zealand DCIO which crashed into Mount Erebus was one of the major surprises in the Royal Commission’s report, into the tragedy. Mr Justice Mahon's finding was in direct conflict with the conclusions reached by the chief inspector of Air’.* Accidents, Mr R. Chippindale.. Mr Justice Mahon supports his findings that exonerate the aircrew with a detailed examination of allegations made by the airline and Civil Aviation Division that the pilots were at fault. He was particularly critical of the Director of Civil Aviation (Captain E. T. Kippenberger). ‘‘lt was stated by the Director that in his opinion a whiteout phenomenon did not exist in this case, or if it did exist, then it played no part in the accident. This of course required him to give some explanation as to why both pilots made coincidentally the same type of gross visual error. He suggested that each may have become afflicted by some mental or psychological defect which controlled their actions. This involved the startling proposition that a combination of physical and psychological malfunctions occurred simultaneously to each pilot. I was

surprised to find that a person with the status of the director should advance- a suggestion which is so palpably absurd. “Then it was suggested that the pilot should not have let down from 17,000 ft to 3000 ft, in an area in which there was known high terrain in the vicinity, without some visual fix. Again, this suggestion was founded upon the false proposition that the air crew w'ere ‘uncertain’ as to their position. If the pilots knew exactly where they were, and saw before them, as they did see, many square miles of flat sea ice visible through very large cloud breaks, then I can see not the slightest objection to circling the aircraft down one and then two descending orbits, operating all the time in clear air, so as to level out, still in clear air, in a position where they still saw on all sides many miles of flat sea ice over an area of 30 or 40 square miles which they had swept visually as they descended. “That decision could not possibly have been wrong, bearing in mind the unimpaired visibility which they had. There could be no question of there being any obligation to get some visual fix prior to let-down, when they were Jetting down in clear

air, and with this wide panorama of flat sea ice perfectly visible below them, and when indeed they were not going forward but were lose height from 17,000 ft to 3000 ft without progressing forward at all.

“So this particular theory of pilot error, in my opinion, •is .also without foundation. I think it harks back to the system operated in the days before the AINS was used. It predicates the presence of a navigator who would be seated in' his plotting and working out as best he could the approximate present position of the aircraft. That would depend upon how right the navigator had been in his prior calculations, and what chance he had had to check succeeding positions by reference to visual landmarks and either the sun or the stars and to what extent his dead reckoning calculations had been affected by wind currents.

‘All this has no application whatever to current navigation of jet aircraft by these unerring and sophisticated aids. The inertial sensor units cannot be wrong. The location of the aircraft is exactly where they, say it is, when the aircraft is flying on nav track. On heading select, or on manual control, a visual fix or a grond-based

aid is required, if the aircraft is not flying VMC. But Captain Collins was flying in VMC throughout, -as even Captain Gemmell eventually accepted, and this meant 20km visibility. But as it happened, he did make a “visual fix.” “The ‘visual fix’ was obtained, in the concerted belief of all members of the flight crew, not long after the aircraft levelled out at 3000 ft, locked back on its nav track, and began to descend. Clearly visible ahead were the two black shorelines of Cape Tennyson and Cape Bird, mistaken by the pilots for Cape Bird and Cape Bernacchi. The plotted flight path on the map showed the nav track to be passing

about midway between the two latter landmarks, and the crew could see that the actual path of the aircraft was similarly directed about midway between the two capes which they could see ahead. “In addition to this, there was the ‘distance to run’ figure on the HSI indicator on the instrument panel. In fact, this displayed the distance to run to the TACAN waypoint, whereas the crew believed, in terms of the information supplied at their briefing, that it referred to the distance to run to the ‘false’ wavpoint just to the west of the Dailey Islands. The figure displayed at about five miles from the axis of the visible shorelines of Lewis Bay would be 35 miles (therebeing a forward error in this respect of ,3.1 miles)

and bv referring to the plotted‘track on their map or maps, the crew would see a DME of 35 miles at about 13 miles from the Cape BirdCape Bernacchi axis. “So when approaching Lewis Bay, the crew saw the identical land features, to the left and right, which they were expecting to see in McMurdo Sound once they descended below the overcast. And the distance out from the ‘false’ waypoint would be sufficiently similar when visually checking the plotted track at a speed of five miles per minute. Thus the ‘visual fix’ was completed. "The next allegation was that the flight crew made a serious and inexplicable error in not identifying Beaufort Island during the course of the two orbits. It was alleged that the position of Beaufort Island would have indicated to the flight crew that they were on the eastern side of the island, whereas if the aircraft was flying on the course assumed by Captain Collins, then it should have been to the east of the orbiting sequence performed by the aircraft,” said Mr Justice Mahon.

“The five persons on the flight deck undoubtedly saw Beaufort Island, and mistook it for a different island altogether, probably, as Mr Shannon thought. Dunlop Island, which is off the Victo-

ria Land coastline. Anyhow, in the minds of the crew the island which they must have seen could not possibly have been Beaufort Island, because as previously indicated. the latter landmark would be many miles away in quite a different location. “This suggestion of error on the part of the flight crew in not indentifying Beaufort Island will therefore be seen to be the result of an apparent confusion of mind on the parts of its proponents. “The next allegation was that having levelled out at 3000 ft Captain Collins should not have elected to fly on towards what was described as an area of poor or deteriorating visibility. This is the aspect referred to by the chief inspector in his report, as being the ‘probable cause’ of the accident. The substance of the chief inspector’s allegations in this respect is that Captain Collins should have decided to climb away about two minutes before’he did. But again this depends upon the essential pre-condition that the crew was ‘uncertain’ of its. position, and this latter postulate is of course quite wrong. Also, it involves the equally wrong proposition that the aircraft was flying towards an area of poor or deteriorating .visibility. "On the contrary, as I have indicated already, the crew ( saw in front of the aircraft a <

long, flat vista of snowcovered ground extending for very many miles. There was no suggestion at all in the. passengers’ photographs or anywhere else, that there was poor visibility ahead. Prints of those passengers' photographs taken to left and right of the aircraft only seconds before impact, showing the shorelines of Cape Tennyson and Cape Bird respectively. are very' indistinct, but this does not mean that the visibility, was any worse then appears in the clear view of Beaufort Island taken shortly before; The ‘last-second’ negatives were developed from film which was still opposite or nearly opposite the lens aperture of the camera at the time of impact and was infiltrated by light when the cameras sustained damage, a point which I have verified with the D.S.I.R. “ - { * “What the captain saw, without doubt, was either an imperfectly defined horizon, or no horizon, and a complete absence of any landmarks in the distance. In addition, he could not raise the Ice Tower for a radar fixi That was why he decided to fly away. I therefore re T gard this suggested element of pilot error, and it was the one in the end fixed upon by the chief inspector, as being not supported by the evidence,” his Honour said.