Originally Posted by
Pastor of Muppets
This crew “believed” they were visual so descent was acceptable both legally and professionally.
Gordon Vette subsequently educated us on sector whiteout and the limitations of then GPWS.
Share the cause. Learn. Move on.......
Even if you completely accept Vette's whiteout hypotheses (and why would you - it was almost completely made up by him and his brother and you'll find nary a scientific paper written on the subject) it was only ever going to be an explanation for what happened at 1500'. There was no "whiteout optical illusion" between 16,000' and 2,000'. What there was, however, immediately to the south enough cloud layers to completely obscure a 13,000' mountain. There was cloud all around and I therefore find it impossible to believe they maintained VFR at all times during the descent from 16000' to 2000'. Which is also evidenced by the fact Collins kept rearming NAV mode after every orbit, which is not consistent with a pilot who is truly VFR and "knows" where he is.