The other question that does not get argued as it should....is when do you stop flying due to the hazards beneath you that make landing out/ditching such a serious gamble? Are we ignoring the patently obivious by putting ourselves in that position? Should we operate in sea states that exceed the certification of the emergency flotation?
SAS raises a very good point that I've oft thought about. How does one go about doing the land immediately thing when flying on top of a fog layer in which the viz is zilch, dead calm water, maybe at night as well. Something you train for? Who of the crew does what in such an event? Mechanics of carrying it out?
So much of what is done in the oil industry would not meet the standards to which airlines operate. Wonder if "land immediately" features in airline checklists.