Erebus white-out was a ‘copybook example’

Press, 27 December 1980, Page 5

Erebus white-out was a ‘copybook example’

By

JOHN MACDONALD.

NZPA special correspondAuckland A United States naval helicopter pilor, Lieutenant Commander Rick Gaw, was uneasy as he flew his red Iroquois over Antarctic sea ice toward- Ross Island, and expressed his misgiving- to his passengers. . Moments earlier, the white flanks of Mount Erebus had gleamed brightly in patchy sunlight, and rock cliff faces on either side of Lewis Bay stood out blackly. Then a sea haze, hardly noticeable at first, rolled up the mountain like a carpet. It seemed to move as rapidly as- the helicopter. What the pilot < saw ahead, in his words, was a “pearly void.’’ . ? The distant cliff faces of Bird Peninsula and Cape Tennyson remained visible on either side, but the haze had wiped away their texture — they could have been 10km away, or smears on the perspex canopy. As the pilot hurriedly prepared to back-track, a patch of sun again broke on the volcano’s flank. Using this as a reference point, he was able to continue, land his aircraft 3000 m from the wreckage of the DCIO, and set down his passengers. What the crew and passengers had experienced was a copybook example of one of the white-out. conditions common in the Antarctic.

The visual phenomenon was a revelation — its suddeness, unexpectedness, and total deception. Three of the five passengers were members of the Mount Erebus crash inquiry. They were the Royal Commissioner (Mr Justice Mahon), the counsel assisting him (Mr W. D. Baragwanath), the technical adviser to the inquiry (Sir Rochford Hughes), and the director of the D.S.I.R.’s Antarctic Division (Mr R. B. Thomson), and the airline’s director of administration (Mr E. Davies). They were flying the same track as Captain James Collins had done. They were almost at the same height and weather conditions were almost a facsimile of those recorded on the. ill-fated day, exactly a year earlier. “Had I not seen the mountain myself earlier, I would never have believed t was there,” his Honour 'said. The impression gained was of low-lying coast to either side, and unobstructed space ahead. It was the condition when a pilot’s eyes, lacking anything to focus on, focuses reflexively on a point about three meters ahead. Because of this it takes moments to re-ori-entate when visibility clears again. Lieutenant Commander Gaw was trained to read the signs, and to take no

chances even in a slowflying helicopter. The experience was one of several during the Royal Commission's Antarctic visit, and highlights the increasing emphasis the inquiry' has placed on so-called illusionistic phenomena, as a factor in the crash.

When leaving McMurdo Station in an Australian Cl3O Hercules aircraft, his Honour spent more time on the now familiar flight deck. .

The crew pointed out to him a long, ice-covered ridge extending from Ross Island into the ice sea. Under the light overcast it was impossible to discern this ridge because it blended so perfectly into the ' shadowless background. Only a black rock at its extremity, provided a reference.

Earlier, on arrival, his Honour had also spent time on l the flight'deck of the R.N.Z.A.F. Hercules, as the pilots flew the identical figure of eight course taken by the DCIO in its final moments. It was brilliant, sunny weather and the Ross Island coast and Mount Erebus stood out with a clarity never seen in more temperate latitudes.

This exercise, apart from showing the lie of the land, exemplified the extremes of clarity and deception found in Antarctica.

Evidence accumulated by the inquiry now points overwhelmingly to the likelihood that Captain T. J. Collins and crew'were deceived by this phenomena, and insidious conditions which can virtually overtake a pilot without his having the slightest suspicion of its presence. The inquiry, which has been remarkable for its ef-

forts in tracking down information, especially scientific evidence, made a point of talking with a legendary Canadian polar pilot during its October visit to North America.

The pilot, Gerry Shannon, was able to confirm the trend of evidence raised before the commission, by several witnesses, including an Air New Zealand pilot, Captain Gordon Vette.

Captain Vette’s hypothesis wa that the crew of the DC10; heading on a direct course‘towards the mountain, saw exactly what the commission did — what appeared to be

limitless clear air ahead. Below, and on either side, he suggested, they could make out areas of black cliff face on either side of Lewis Bay. To a crew not familiar with the lie of. the land, who thought they were heading down McMurdo. Sound, these hazy landmarks were unconsciously mistaken for the coastline of the sound.

Captain Vette’s theory hit a chord and a parallel train of thought already raised in the minds of inquiry members.

The question of whiteouts was mentioned briefly in the report of the Chief Inspecter of Air Accidents (Mr R. Chippindale). He said there was a high potential for this condition at the time of the crash. This was as far as a technical report could safely take the question. It had to rest on known facts.

So what is the point in pressing this line of inquiry which can never be proved beyond a 99 per cent certainty, and which, in any ■ case, was the end

■».result of at train of circumstances' which went -awry?

The day-to-day evidence provides the answers without stepping too closely to sub-judice speculation. - If, in fact, Captain Collins and crew were deceived by an illusion and believed the path ahead was clear, they obviously had no knowledge that the aircraft, track was programmed to take them right over the top of Erebus. Otherwise, they would not have descended to 1500 ft. The only alternative is >that they believed the computer had programmed the. machine to fly over the flat ice of McMurdo ■Sound, about 25 nautical miles to the west. One certainty is that they were not lost in the sense of an equipment malfunction; the navigation system was working perfectly. The implications for the company of this belief being upheld are obvious. Less obvious is the question of blameworthiness which has been attached to Captain Collins and crew. Their basic breach of good airmanship was said to be for flying too low in, conditions which did not allow them to see ahead for 40 miles, the regulatory minimum. Admissions at the inquiry have shown that a prohibition on going lower than 6000 ft, cited in the Chippindale report, was by no means a . hard and fast rule, neither was it accepted as such by most pilots. That leaves the question of visibility as the main reason for attaching blame to the crew. For that reason the white-out theory is of crucial