IRAP Administrator
08-03-2007, 11:07 PM
It was the final day of Intro class, and it was time for the lights out air share drill. Diver A and B and instructor proceed into Peacock I and up the Peanut line to the breakdown room to see the drop-off. After some sightseeing, we turned the dive and returned down the bedding plane. At the 400' arrow, we began the drill. This is the area of the cave where you have to cross over the line several times in the relatively tight bedding plane. We started on the left side of the line, with Diver A leading and breathing from B's long hose. The tunnel goes to the right, and we performed a successful line side change, and proceed on. The tunnel goes back to the left, and we switched over again. Then it became really interesting.
Diver A felt as if it is time to switch back to the right, due to the rocks on the left side. Diver A removed B's hand, and pushed B backward, indicating the switch. Diver A then moved across the line, swapping hands holding the line, and waited for Diver B. Diver B recognized the line had stopped moving, and executed the line switch as well. B grabbed A's arm and gave a gentle nudge to signify move forward. Diver A moved and "bang" the tank hits the ceiling. B wondered what was taking so long, and pushed again, thinking that A didn't feel or understand the signal. A tried to move forward again, and became wedged further between the ceiling and the floor. B was oblivious to this, and pushed again, wedging A even further in while A is feverishly trying to gain traction in reverse.
A thinks "What the heck is going on here, I know it wasn't this narrow coming in!" B thinks "What the heck is taking A so long?" By this time, A decides to turn and push B back, to try and un-wedge. In the process of turning, the regulator is yanked out of A's mouth and falls away. Unable to locate the fallen regulator, A decides to abort the drill, desperately grabs the necklace reg, and pops the light on. B sees light, notices the reg bouncing off of the bottom and thinks "oh s^^^ we really f^^^^d this one up." Viz is crap from all the jostling on the rocks, and the instructor is trying to maneuver into place to try to resolve the issues. We decide to abort and proceed out of the cave because B is low on gas, completely dejected and frustrated. None of us has any clue what happened, and only after half an hour of debrief and reflection on the surface did we figure it out.
Here's what happened: In Peacock I on the Peanut line, the line makes a 90 degree turn right to exit the bedding plane. But the line also goes straight and wraps around a rock to hold it into place. The passage going straight is way too narrow for a backmounted diver to squeeze into.
Diver A, in the process of switching sides of the line, had one hand immediately before the line heading to the right, and the other hand immediately after it. Diver B, in switching sides and getting back into touch contact with Diver A, completely missed the line with the right hand, while the left hand remained before the turn. Because of the cave configuration, the instructor was unable to move into a position to provide any assistance. In turning, because the hose was routed very poorly to get to Diver A's mouth, it snagged on something and was yanked out.
What we learned:
1) Any time you switch hands on the line, ALWAYS make sure you grab your hand first, and follow the line right where it comes out of your other hand. Otherwise you may miss that critical "T" and go down the wrong path.
2) When the following diver resumes contact with the lead diver, always feel the line from your hand all the way up to the lead diver's hand, to ensure a line was not missed. Otherwise, the "backup brain" can not function properly.
3) Hose routing is critical. Both divers should always have one hand on the hose. It should preferably be in the hand that is on the line, and should always go underneath the lead diver's body, not over it. It's difficult to visualize, and even more difficult to try out unless you are horizontal in the water, but it works. If you don't know this intuitively, or if it's confusing you, try it out next time; you'll be surprised. We were. Try switching sides during an S-drill and see what happens.
The worst part of the OOA drill was that if it was for real, then diver A may not have survived. The best part about it was that we learned a whole lot; probably a lot more than we would have if we had done the drill perfectly.
Through this experience, it strongly reinforced that a simple S-drill is not sufficient for OOA practice. You need to practice air sharing regularly, WHILE routing your hose properly underneath your body, WHILE holding the hose and the line, WHILE ensuring you don't bash your head on an invisible rock in the darkness ahead of you. On the way out of the cave, we occasionally practice this situation to ensure we have it right, so we won't be stressed out in a true OOA situation.
I hope this has been valuable, and has at least started some of you thinking; any feedback is welcomed via the main forum.
Diver A felt as if it is time to switch back to the right, due to the rocks on the left side. Diver A removed B's hand, and pushed B backward, indicating the switch. Diver A then moved across the line, swapping hands holding the line, and waited for Diver B. Diver B recognized the line had stopped moving, and executed the line switch as well. B grabbed A's arm and gave a gentle nudge to signify move forward. Diver A moved and "bang" the tank hits the ceiling. B wondered what was taking so long, and pushed again, thinking that A didn't feel or understand the signal. A tried to move forward again, and became wedged further between the ceiling and the floor. B was oblivious to this, and pushed again, wedging A even further in while A is feverishly trying to gain traction in reverse.
A thinks "What the heck is going on here, I know it wasn't this narrow coming in!" B thinks "What the heck is taking A so long?" By this time, A decides to turn and push B back, to try and un-wedge. In the process of turning, the regulator is yanked out of A's mouth and falls away. Unable to locate the fallen regulator, A decides to abort the drill, desperately grabs the necklace reg, and pops the light on. B sees light, notices the reg bouncing off of the bottom and thinks "oh s^^^ we really f^^^^d this one up." Viz is crap from all the jostling on the rocks, and the instructor is trying to maneuver into place to try to resolve the issues. We decide to abort and proceed out of the cave because B is low on gas, completely dejected and frustrated. None of us has any clue what happened, and only after half an hour of debrief and reflection on the surface did we figure it out.
Here's what happened: In Peacock I on the Peanut line, the line makes a 90 degree turn right to exit the bedding plane. But the line also goes straight and wraps around a rock to hold it into place. The passage going straight is way too narrow for a backmounted diver to squeeze into.
Diver A, in the process of switching sides of the line, had one hand immediately before the line heading to the right, and the other hand immediately after it. Diver B, in switching sides and getting back into touch contact with Diver A, completely missed the line with the right hand, while the left hand remained before the turn. Because of the cave configuration, the instructor was unable to move into a position to provide any assistance. In turning, because the hose was routed very poorly to get to Diver A's mouth, it snagged on something and was yanked out.
What we learned:
1) Any time you switch hands on the line, ALWAYS make sure you grab your hand first, and follow the line right where it comes out of your other hand. Otherwise you may miss that critical "T" and go down the wrong path.
2) When the following diver resumes contact with the lead diver, always feel the line from your hand all the way up to the lead diver's hand, to ensure a line was not missed. Otherwise, the "backup brain" can not function properly.
3) Hose routing is critical. Both divers should always have one hand on the hose. It should preferably be in the hand that is on the line, and should always go underneath the lead diver's body, not over it. It's difficult to visualize, and even more difficult to try out unless you are horizontal in the water, but it works. If you don't know this intuitively, or if it's confusing you, try it out next time; you'll be surprised. We were. Try switching sides during an S-drill and see what happens.
The worst part of the OOA drill was that if it was for real, then diver A may not have survived. The best part about it was that we learned a whole lot; probably a lot more than we would have if we had done the drill perfectly.
Through this experience, it strongly reinforced that a simple S-drill is not sufficient for OOA practice. You need to practice air sharing regularly, WHILE routing your hose properly underneath your body, WHILE holding the hose and the line, WHILE ensuring you don't bash your head on an invisible rock in the darkness ahead of you. On the way out of the cave, we occasionally practice this situation to ensure we have it right, so we won't be stressed out in a true OOA situation.
I hope this has been valuable, and has at least started some of you thinking; any feedback is welcomed via the main forum.