Mark, who is suspecting hypoxia; the masses of armchair investigators or the real investigators?
Loss of communication as early as 15 minutes into this flight caught my eye immediately as something potentially other than hypoxia. The small private jet owning community should not be waiting for the final report on this one to have serious conversations with their inner souls about how much they are really saving by conducting single pilot operations. Even with highly experienced pilots as is the case here, they are breaking the redundancy chain. At a minimum, they should have this conversation for the sake of the next, and the next, and the next 2 year old they put on board.