fantome,
Oops, sorry, missed that one, at the top above the cover of another publication.
But why does not the requirements for descent, that states absolutely nothing about invitations from Air Traffic Controllers, VMC maintaining own terrain separation, or any other debatable points, get so little traction in this thread.
"Delete all reference in briefing dated 23/10/79. Note that the only let-down procedure available is VMC below FL160(16000ft) to 6000ft as follows:
1. Vis 20 km plus.
2. No snow shower in area.
3. Avoid Mt Erebus area by operating in an arc from 120 degree Grid to 270 degree Grid from McMurdo Field, within 20 nm of TACAN CH 29.
4. Descent to be coordinated with local radar control as they may have other traffic in the area."
Which one of these requirements was met??
It is very clear, it states exactly what the requirements for descent are, it states nothing about unless you find a hole in the cloud then you may design your own descent procedure, and there can be no debate that the crew were not aware of its existence, a copy was found in the wreckage of the cockpit.