Old but interesting thread. I thought of reviving this thread to share my own experiences. We learn through mistakes of others or ourselves.
I agree with Alvin Ho when he mentioned, "I would say most OOA situations are due to diver error. equipment failure is seldom the issue when you read dive accident reports. ".
There was 1 incident of equipment failure that I came across. The hose burst during the dive, and air escape rapidly.
Coming to my personal experiences, I had 2 OOA situations in the last 2 years. Sounds stupid but here's the experiences.
1. Cebu Moalboal (Feb 2015)
It was my own mistake. One word, STUPID!
In short, I was down to about 50 bars, when we came to this small cave. There were 2 teams ahead of us, and instead of signalling to the guide that i'm down to 50 bars, I was stupid. In short, after that cave, I was down to about 20 bars. I should have immediately told the guide, again, stupidity. We were going shallow, so I presumed we are going for safety stop.
At safety stop, I was OOA. First thought, worse case scenario, shoot up. My buddy happened to face me when I was OOA and I signalled. Due to the initial panic, I took the spare, stuffed it into my mouth and breath! All the precaution learnt were forgotten, I drank 2 mouths of water. Threw that spare, took back my own (very very limited air at most) and drank another mouth of water. Yes, I panicked, I freaked out, I was scared! Luckily, the guide was facing me then, and quickly took his spare and purge water lodge in it, and passed to me. I was on deco too!
That was the stupidest dive! But that was the dive that I learn diving all over again! This could be the scariest moments in my life. I was almost dumbfound after that dive for the next 2 hours (but I did a last dive for that trip after that).
2. Bali, Padangbai (Sep 2016)
This one was fully aware! The dive was at Padangbai, Jetty. It was shallow dive, about 14 meters at most. The whole dive lasted (including safety stop) 84 mins.
From the first bad experience, all dives thereafter, were filled with precautionary. I do constant gauge checks (every 5-10 minutes), dive computer checks, etc. As I approached 50 bars, I was consciously checking gauge every other minute. During safety stop, OOA happened again.
Well, experience... so I was a lot more calm, took the spare regulator of my buddy and complete the safety stop. Throughout the safety stop sharing of a single take, my eyes were glued on the gauge and my dive computer.
In theory, OOA feeling is, we need some effort to breath (air doesn't flow out readily). But in actual, if one haven't experience it, how does it feel like? Try obstruct your lips/mouth with your fingers and breath. You should feel certain resistance.
Early this year, while doing Deep Diver course, my instructor had highlighted the importance of Deep Stop. I wonder if many divers are aware of this (experienced divers, or those who really read/learn would know)? So far, I have not encounter any dive where were were consciously doing deep stop. Perhaps the guides had conducted deep stop but not told divers. It is us, divers, who should be conscious than expect the guide to do it.
Any dives beyond 20 meters, should come with a deep stop (half way mark) for 1 minute. This is a habit I practice since my Deep Diver course. When I did 40m, my instructor then, told me, we will do 2 deep stop, before doing the usual safety stop. So yes, anyone who isn't aware, do practice deep stop in your future dives.