I know there are those who say we should not even discuss any accident until the full investigation is over, and man, I almost hate to weigh-in on this thing. But as a long-time pilot I can't resist offering my thoughts.
What helipilot214 says is true: Who knows what happened! I think we can be fairly sure of only one or two things: 1) John was not sitting way in the back, seat reclined, feet up, not a care in the world. I'd be willing to bet real money that he was right there, between the pilot seats, "coaching" them as third crewmember. I know I would have been.
Secondly, it was *not* CFIT, that much is obvious. The term implies that the aircraft was under control up to the point of impact. But the 139's contact with the water was surely not "controlled." If they hit at such an apparently low forward speed, then neither of the two "pilots" had control of anything, certainly not the airspeed and absolutely not the altitude.
It's a very sad accident if what is alleged is true. We can only wonder after the fact what any of us would have done in a similar situation. (For the record, I often fly over dark-dark areas at night with my unrated boss. He sometimes wants to "take the stick" and see what flying in such conditions is like. I always decline, sometimes forcefully, because I don't want the possibility of him putting us into an attitude from which recovery would be difficult even for me. He grumbles and complains, but it's just too damn bad and it tests my skills of diplomacy to the max, as many of you out there can undoubtedly sympathize.)