Well, Superlyte, that's a horrible story, but one which would never have happened if the basic rules of cave diving had been followed. I had a big argument yesterday with a buddy who was suggesting that it was not necessary to mark intersections, if you knew the cave well; I exploded at him and told him I will never, ever, EVER pass an intersection and not mark the exit direction.
With regards to the original question, I think there are two ways to plan a dive. One is to ensure one has EVERYTHING one might need for any conceivable situation, in one's skill set or on one's person. This is the solo diving approach.
The other is to share some resources. For example, I do not dive with a spare gauge. If my gauge fails, we abort the dive, and exit using my buddy's. Similarly, my spare gas is on my buddy's back. We may not have any one person carrying all the jump spools for the dive; it may be planned that, at some point, the leader will ask for a spool from one of his teammates.
In any dive, I'm reasonably comfortable assuming no more than one catastrophic failure -- and that, if everyone involved responds calmly and appropriately to that failure, no more will occur. Equipment failure, navigation failure, illness or injury are catastrophic failures -- but so is buddy separation. I do not assume both will occur at once. Maybe someday I'll find out that is not conservative enough, but a lot of people I know, who have done far more dives, and more difficult dives than I will ever do, operate under that structure and have done so safely.
With regards to the original question, I think there are two ways to plan a dive. One is to ensure one has EVERYTHING one might need for any conceivable situation, in one's skill set or on one's person. This is the solo diving approach.
The other is to share some resources. For example, I do not dive with a spare gauge. If my gauge fails, we abort the dive, and exit using my buddy's. Similarly, my spare gas is on my buddy's back. We may not have any one person carrying all the jump spools for the dive; it may be planned that, at some point, the leader will ask for a spool from one of his teammates.
In any dive, I'm reasonably comfortable assuming no more than one catastrophic failure -- and that, if everyone involved responds calmly and appropriately to that failure, no more will occur. Equipment failure, navigation failure, illness or injury are catastrophic failures -- but so is buddy separation. I do not assume both will occur at once. Maybe someday I'll find out that is not conservative enough, but a lot of people I know, who have done far more dives, and more difficult dives than I will ever do, operate under that structure and have done so safely.
