I have experienced this state many times in life, it usually triggers when I'm deeply focused on a task. In this state things become easy and time seems to fly by. There is another state though and that one has only triggered in "life and death" situations for me. One was during an actual life and death situation involving a rock slide and the other when playing Counter-Strike and my whole team got wiped out and the opposing team converged on my position.
In both of those occasions you have your usual emotional detachment but instead feel as if you are watching yourself do the actions instead of feeling like you are doing them. Time slows down though, and even though you are relaxed and calm you feel the performance difference from what you are normally able to do and your fear is the knowledge that if you come out of this state before the danger is over you are done for.
That second state feels different and I'm sure its the 'flow' people that do extreme sports talk about. Is there a different name for that state? or is that too just called 'flow' aswell?.