To clarify sector whiteout, the following is from an aviation safety newsletter:-
Whiteout
Whiteout is a snow related phenomenon that can prove exceedingly serious. There are two types of whiteout: one caused by blowing snow, the other by lack of definition and texture. Both can cause loss of orientation.
Blowing Snow
This phenomenon usually occurs on or close to the ground in otherwise good weather, when snow on the ground gets blown either by the wind or by the propeller or engine blast. Suddenly, you find yourself in IFR conditions, unable to see very much, but usually in a VFR frame of mind. The sudden and unexpected transition can catch you unaware. Helicopter pilots have to be particularly careful about the blowing snow phenomenon.
Sector Whiteout
The second type, known as sector whiteout, is much more insidious than the first, because it can occur in VFR weather with no blowing snow. Sector whiteout happens under a low to medium overcast in snow-covered areas with featureless terrain. When the sun is in a certain position, its rays are reflected back and forth between the surface and the overcast and cause all texture on the ground to disappear, with no discernible distinction between the ground and the clouds. Because our minds are programmed to observe a line between ground and sky, any slight shadow can cause us to believe it is the horizon.
This type of whiteout was one of the major contributing causes of the accident where a DC-10 flew straight into Mount Erebus in the Antarctic though visibility was 50 miles. The particular cloud that day, combined with the position of the sun, caused the mountain slopes to merge visually with the overcast. The crew, having no visual cues from the ground, did not realize the terrain was rising.
btw,
prospector, I don`t see the relevance of Derek Ellis` experience as a Concorde pilot to this subject
