How do you come to that conclusion when the photographic evidence says otherwise?
What photographic evidence?? there were no photos of Mt Erebus, the only photo of Ross Island showed rock cliffs around the coast, below the cloud base at 1,500ft, the rocks that would not give a radar return according to Mahon.
It was obviously VMC out to the West where the flight was advised to go, and behind them, that showed up Beaufort Island, but why no photo to the south, could it be that no one wanted to waste film taking shots of cloud?