it sounds like a great deal of planning DID go into the dive.
The primary mistake that was made was that the circuit was not set up as we learn it in cave class.
A circuit usually requires three dives. The short version is this:
During dive number one the circuit is set up. The team places a jump line to connect to the circuit, swims along the circuit line and places a cookie on the line when turn pressure is reached.
On dive number two the jump is put in at the other end of the circuit line and the team swims into the circuit from the other direction until it gets to the cookie or hits turn pressure. If the turn pressure is reached before getting to the cookie, the dive is obviously turned.
During dive #3 the jumps are removed and the circuit that has been set up is cleaned up.
In this case the dive was not set up. John could have been on a completely different line leading to some place not being the exit. That in itself would not be a problem, had the team turned when reaching turn pressure to return on the exact path. As I understand, the team continued in the hope that their line was actually the one leading back towards the exit, which luckily turned out to be the case.
---------- Post added January 13th, 2016 at 11:16 PM ----------
1. Did your cave training discuss anxiety? Did it talk about how to avoid it? Did it talk about how to manage it once it appears? If it doesn't should it and how?
2. Is this something that divers are wary of talking about? Should it be discussed more?
3. Do others find that hypercapnia is a factor? What other factors are relevant?
4. What do you do when anxiety appears?
1. Yes, my training did cover it. We talked about how to avoid anxiety and how to resolve it. A good start is, as you said, to stop and relax. Resolve any problems that might exist before continuing with other tasks. Problems tend to stack up. Preferably end the dive and don't risk pushing onward in the hope that your anxiety gets better.
Usually it will not get better. Accept the way you feel, call the dive and try again another day
2. Yes, I feel it needs to be talked about more. Many people will not admit to it, but my take is that the majority of all cave divers (and even divers in general) have experienced anxiety situations like you describe
3. Hypercapnia is a major factor and needs to be avoided at all cost. Another contributor can be nitrogen narcosis.
4. As detailed in 1. Also try to clear negative thoughts out of your head and replace them with positive thoughts. Don't let thoughts like "if I don't find the line again, I'll die" control you. Think positive, relax and solve the problem if there is one. You need to regain control of the situation. OK'ing the line, as you did, is a good start, as may be getting in touch contact with your buddy if the vis is poor and that is of concern to you.
The usual procedure is to overcome anxiety is to advance progressively dive by dive. As your diving progresses, your comfort level will increase greatly.