A couple of people hating on this. Despite the obvious fact that you can in fact get lost on a trail, the progress of autonomous rescue drones doesn't just end at following trails.
Once they're able to detect trails and follow them looking for people, the next step would be detecting signs of where they might have wandered off trail, or (especially in snowy conditions) detecting and following where they have started their own trail.
Once they're able to detect trails and follow them looking for people, the next step would be detecting signs of where they might have wandered off trail, or (especially in snowy conditions) detecting and following where they have started their own trail.