A free-flowing regulator leads to an out-of-gas ascent
The wreck was in water 127 fsw (38 msw) deep. The currents were very strong that day, with water temperatures in the 80's F (high 20's C). We descended in pairs; my partner and I both had 3000 psi (207 bar) of air. During the dive we explored the ship and compartments, I checked my gauge and had 1500 psi (~100 bar) when we were on the far end away from our surface rope. As we began our swim to the rope I was watching my gauge and noticed it had dropped below 1000 psi (70 bar), I did a quick check and found my alternate air source blowing air. I attempted to get it to stop with no luck. I let my partner know and then I breathed from my alternate air source to make the most of the air I was losing. At 90 fsw (27 msw) I ran out of air, my partner gave me his octopus and we continued our ascent. At our safety stop we had 500 psi (35 bar) so we were forced to cut our safety stop short and surface. We made it back onto the boat and were happy to be back.
Prior to any dive, divers should have a gas management plan, even if it just a rough idea of how fast the gas should be consumed based on the dive depth, conditions and previous experience. This diver kept a cool head when he discovered lower remaining pressure than expected. He signaled his buddy and they commenced an ascent, then his buddy donated air on the way up. Here is yet another clear example of when diving with a buddy has prevented a rapid ascent when something unexpected happened. It is also a reminder to regularly practice emergency air sharing.