They thought they *were* under radar guidance, and so did the Captain (by way of the transponder light blinking on and off).
If you were aware of basic rules and regulations appertaining to this flight you might come up with something better to justify your posts.
Radar descent could not be started until there was direct VHF contact between FLT 901 and McMurdo radar.
VHF contact was never established. All communication was via HF.
This has been stated so many time one wonders if you bother to read any of the posts.
We will try again.
VHF is line of sight, there was no radar contact, there was no reception of the DME from the TACAN and no receipt of VHF communications. They were well within range of these services, they should have had reception but they did not, now what could be the only thing that could stop reception of these services?? they were not where they thought they were because Mt Erebus was between them and the TX stations.