"And you run.
Flinging with reckless abandon. Down the ridge, bouncing off trees, following the voice. And you're drenched in sweat. "How far did I just run, I can't even see me campsite from here?" Could have been 5 minutes, could have been 15, could have been 30. and you see her, where she fell, a woman, in the snow, and a child is crying, and a man, maybe husband swaying, holding it together, and he says, she can;t move. and all you have is your thermos just hot water, it was what was in your hands, when you heard it, and hot water, not even tea, and just your jacket, and your headlamp, "OMG my headlamp!" so lucky, because it was approaching dusk"
I have headed out more than once because of the ominous cry for help. But never once was it my firt instinct to start running/snowshoeing/split boarding through the wilderness with out even having the proper tools to help someone(shovel, knife, lighter, head lamp, GPS). Thats like trying to save some one from deadly rapids by diving in after them fully clothed with no life jacket. And while the color of the clothes might help a little your best bet is going to be the emergency whistle... It doesnt require a line of site to be useful and works at night where it would be hard to see no matter what color.
Edit: To be perfectly honest I am usually in no hurry to head out to help some one at night and the attitude is more like "Ugh im so comfortable and ready to be asleep what asshole is lost in the dark this time?" Usually its people that think they are smarter than they are and people that over estimate there ability(Vanity). Neither of which I have patience for. Obviously this is not the case all he time but its the only circustances I've ran into.