Mine was when I was diving commercially. I was at 250' on surface supplied with limited bail-out and the console operator wasn't suppling the +10' gas supply. Didn't know if it was a malfunction. The stage was not working so I couldn't count on doing Sur "D", my Comm was out and I was facing the distinct possibility of having to surface with out proper Deco. They were able to fix the gas supply but I had to do In-water Deco. Scared the crap outta me.
Emeralds are real Gems!