Sector whiteout (as opposed to whiteout caused by increasing intensity of snow fall, and corresponding visibility to whiteout conditions) is probably something many of you may have experienced, but may not have realised it at the time eg. driving on a cloudy/misty day (or night) and ascending a hill or mountain - moreso is the effect noticeable ...or less obvious, if the ground is snow/sand covered.
Several years ago, driving to Mt Mackinley outside Anchorage, we in the car experienced this phenomenom - the horizon appeared slightly obscured and (slightly) indistinct, but nonetheless there, with the road disappearing hazily into it, and as we were still able to see the flat, snow covered fields on either side it appeared that we would continue our journey under the overcast.
As the car continued its ascent, it was obvious that we were slowly entering into the base of the cloud, and visibility dramatically reducing.
It appears to me, prospector, that your ONLY knowledge of this accident wrt airline and flying operations, has been gained through books, and is thus extremely limited.
You appear to me, to be devoid of any ACTUAL commercial, operational flying experience, and the ability of crews to SAFELY carry out a visual descent, without completing a full instrument approach.
Capt Collins would have been quite "legal" in descending to the enroute MEA, or the MSA, and then continuing further down if visual contact with the terrain had been made.
From the reports I have read, I believe that that was indeed the case, however, due to the undulating, featureless nature of the Antarctic terrain, a positive "fix" would have been difficult to confirm.
But making it IMPOSSIBLE, was the fact that the final co-ordinates had been changed, and the position of the aircraft was not where the crew were expecting it to be, from the briefings they had received.
Your half-smart, 1-line quip from an earlier post still leaves my question of why Derek`s Concorde experience is relevant, unanswered (yes, I know the gentleman - I flew with him in SQ (747).....and Ian Gemmel during his time at Ansett New Zealand[737]).