"The CP, more than likely, thought he was VMC"? Demonstrably not true. He had already summarised sector whiteout; "Very difficult to tell the difference between the cloud and the ice." He knew that from flying sorties for the RNZAF out of Wigram in the 1950s. He knew full well that he would not be VMC below the cloud layer. The reason for has expressly declaring that he was VMC was because he was actually relying on the AINS to confirm his position, contrary to rules that he also knew full well. Mahon placed great significance on his locking the aircraft back onto the nav track at 1500 feet. So do I, but to the opposite effect. Wasn't he supposed to be VMC? (I apologise for not concluding this post with some feigned politeness and another ******** comment about flight safety.)