Whole transcript here (Annex C):
Chippindale Report
The point is that he was going down the hole
before the transponder started. At the time that occured, the aircraft was descending from 13000 feet to 10000 feet, already well under MSA. So he definitely ditched the plan.
Vette's attempted explanation is difficult to fathom:
"There was a nagging doubt at the back of Jim Collins' mind, possibly associated with the briefing, that the approach radar would be unable to pick them up above 6000 feet." (Impact Erebus, p130)
There is no evidence of anything like that being said at the briefing, and it would make no sense. The whole point of the radar was to confirm an aircraft's position before it went below MSA.
"A quick mental reckoning put him about ten minutes before the McMurdo Sound waypoint near the Dailey Islands if he continued on the same heading, holding the same height. But there was no point in the exercise. The edge of the main cloud front was drawing closer and he would have to get beneath it before he could make the dog's-leg turn to hook in to the south of the island, and fly visually under radar guidance to the ice runway and the TACAN." (p132)
No point in the exercise? What's wrong with staying above MSA until his position was confirmed by radar, turning left towards Mac Station, and descending through the cloud base under radar guidance? After all, that was how the military pilots did it.