You are talking about two different things. VMC is visual meteorological conditions, VFR is Visual Flight Rules. The flights were, to the best of my knowledge, always operated under IFR, Instrument Flight Rules.
My mistake saying VFR rather than VMC. The flights had a VMC segment, that was the scenic part of the flight. How are the pax going to view the scenery, the entire purpose of the flight, if the aircraft is not in VMC conditions. So using the correct terminology, what conditions were considered to be VMC?
In your,
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.
you forgot to mention that the descent from 16,000 to the minimum of 6,000 had to be in VMC. So what were the stipulated VMC limits? There is nothing in the report that I can find, though the regs in force at the time state 8Km vis, 1 mile horizontally & 1,000 feet vertically.
Since the NDB was out presumably they had to identify McMurdo by a combination of DME read out and INS.
For those asking about maps.
Topographical maps were not issued for use on the flight. With the exception of a Photostat copy of a small insert enlargement of a map of Ross Island (1:1,000,000), these were not issued to the crew until the day of the flight, and were of a relatively small scale i.e. 1:5,000,000 and 1:3,000,000.
More importantly, the strip map of the route from Christchurch to McMurdo issued on the day of the flight also had two tracks printed on it both depicting a passage to the west of Ross Island. Positive reinforcement of the track the Captain had taken the trouble of plotting in his atlas.