I'm probably going to regret crawling out of my hole to post, but it's late, and I'm bored. I've seen a link to this flow chart before, I can't remember if it was here or TDS. I'll admit up front that I'm a novice Apprentice Cave diver, but I'm pretty sure the last thing I want to think about if I have a gas problem is this flow chart. I'd much rather isolate first and go from there, and then the worst case is that I've saved half my remaining gas which is enough for me to exit, even if I dove to thirds and was at my maximum point of penetration when the problem occured.