I was involved in a close call back in early June. We were diving off a boat in a lake here in GA. I had never dove with this guy before but he seemed pretty squared away so it was a go. The plan was we'd hit the water, surface swim about 50' away from the boat, drop to 10', do a bubble check and a quick S-drill, then descend to about 65' and work our way back to the boat.
We hit the water did the short surface swim, everything was fine. We or should I say I dropped to 10' and stopped for the bubble check but the other guy just kept descending. My first though was he forgot about the bubble check and S-drill. I waited on him for maybe 5 seconds and then I followed his bubble trail down only to meet him coming back up. I could tell something was wrong by how hard he was kicking. I gave him an OK and he shook his head NO but he didn't indicate his problem.
I followed him up and as soon as we corked he said "help, I can't stay up!". I actually suprised myself- I didn't think, I just acted- I got a good grip on his harness and hit my inflator until my opv started to vent. I remember looking him dead in the eyes and saying "it's ok, I got you, we're cool".
I kept us both up and we swam back to the boat and called it a day. The bad thing about all this was he really hurt his ears as he couldn't equalize on his uncontrolled descent.
What caused all this was that his inflator hose elbow had came off at the wing.