That is actually not a bad idea, and is something we don't think about too often. Like Frank, I typically have my phone on my belt, as well as a small flashlight in my pocket that I find very handy for all sorts of things.

I once worked night shift in a windowless factory that made dot matrix printers. One night the power went out and there was about a 30 second delay before the backup generator kicked on. It was the darkest dark that I think I had ever experienced, a total utter lack of any light as this was long before we all carried battery powered doo-dads of all sorts on our persons. You really didn't dare move as the place was like a rat maze of roller track and benches. That thirty or so seconds seemed pretty long.