There was an alternative route, to the South Magnetic Pole. The alternative route was available if the bad weather was known about before getting to Cape Hallett. After Cape Hallett, the captain had a free hand as to the track and could go to other areas. While heading towards McMurdo Station after passing Cape Hallett, Captain Collins was informed of the bad weather at McMurdo Station.. He was just about to go somewhere else when McMurdo Station offered him a radar- assisted descent. Collins gladly accepted the offer, announced the plan to the passengers, and waited for the radar operator to make contact. While waiting, Collins was told that the weather over the Dry Valleys was perfect. His response? "I prefer here first." So he kept on the track to McMurdo Station and he kept on trying to make contact with the radar operator. Then, he came to a large hole in the cloud layer, so without any discussion with his crew he started descending from 18000 feet in a figure-of-eight track. There had been no contact with the radar operator so there had been no confirmation of his position, but he got around this by pretending to be flying visually. The word "pretending" is accurate because Collins knew about white-out and knew that he would not have visual conditions below the cloud layer. What he was actually relying on was the aircraft's inertial navigation system - but the INS was not to be used to go below the height of a nearby mountain. Why? Because it might be wrong, and in this case, it was.