Situation: My buddy and I are sidemount diving on a summer's day at Madison Blue. It is late afternoon, so the spring basin is chock full of swimmers. This will be the last dive of the day, so we don't want to leave anything in the cave.

Plan: We decide to enter at Martz sink to avoid the crowds and then traverse to the basin where it is easier to exit. The line at Martz runs to open water; we will visual the gap from the Martz sink line to the main line, then install a jump line at the first left to the banana room, install a gap to get across the banana room and do the Godzilla circuit. We will take the same path back out, cleaning up our spools as we go. Based on time and prior nitrogen load, this is a planned deco dive. We will carry our O2 bottles with us, but drop them after installing the first jump to avoid damaging the narrow passage. I didn't want to leave the O2 bottles out on the main line, so the plan is to clip the O2 bottles on top of the line anchors; this will prevent stirring up the silty floor in our chosen path.

The Dive: All goes well getting to the main line and installing the jump. I smoothly unclip my O2 bottle while floating near the ceiling. I go head-down to clip my bottle to the anchor and the trouble begins. I had adjusted the angle on my inflator before the dive (I dive a Nomad with an inverted inflator, so it fills from the bottom and dumps up top) and hadn't secured it properly. As soon as I went head-down, I started plummeting towards the floor. I jammed on my wing and drysuit inflators but still ended up on the floor. While there I had the presence of mind to clip off my O2 bottle to the line and free my other hand. Then the effects of my rapid inflation kicked in and I rocketed towards the ceiling.

As I struggled to control my buoyancy and troubleshoot my wing, my buddy clipped of her O2 and wisely decided to get out of the siltout by proceeding slightly forward. Meanwhile, I managed to get under control and get my inflator screwed back on right. I'm floating near the ceiling and can't really see anything. I decide to wait it out, and after a minute or so I am rewarded with the sight of the line and and the glow of my buddy's light.

As I proceed towards my buddy, her primary light fails. She deploys a second primary light (we had discussed this contingency) but is now short one light. The passage we are now in is too tight to get side by side, but I recognize the situation and hand her my #3 backup light from behind. She stows this light and we continue towards the banana room. Once we get into more open cave, we have a quick hand-signal discussion and decide to continue to dive as planned. We complete the rest of the dive and deco without incident.

Discussion: Our planned route may have been a little convoluted. Once making it to the Monkey room, out quickest and easiest exit would have been the basin, but we didn't have a continuous line going that way. Once back on the mainline from where we jumped, out shortest exit was Martz sink, but our visual jump meant we no longer had a continuous guideline to that point.

It probably would have been better to leave the O2 bottles on the main line. Clipping them to the line anchors on a silty floor was unnecessarily complex. The O2 really wasn't even necessary for the deco we had planned, but it was desirable for safety. Another option would have been to just keep the bottles on throughout the dive. Our route through the cave wasn't THAT tight.

I should have tested my wing better after making the adjustment. Even after the dive, I found it still wasn't seated right. Fully inflating the wing would have caught my mistake.

We chose to dive with my buddy using an iffy primary light. As per Murphy's law, it failed at the most inopportune time. The plan was for her to carry an extra primary and switch to it if necessary, but somehow she overlooked carrying the necessary backup lights for executing the plan.

Both of us just about thumbed the dive. The chain of events was quickly building to a possible accident. Instead, we took a minute to calmly evaluate the situation and made the decision to continue the dive. I contribute this to a well-briefed plan, familiarity with the cave, confidence in equipment and skills, and plenty of cave dives as a team.