Hypothermia could be the ultimate culprit here, it often is when you see people make unfathomable decisions. If the pilot was working for three hours in nearly freezing weather clearing sloppy wet snow, he would have likely been hypothermic without realizing it. Long before you have any of the obvious symptoms, your reasoning power is impaired. It has happened to me and people around me; after foolishly deciding to snorkel in cold ocean water I caught myself towing my kayak back 1/2 mile to the boat rather than either going ashore to warm up or simply getting in the kayak and paddling. There are many, many examples up here in the Pacific Northwest of poor decision making that led to tragedies or near-tragedies that come down to slightly hypothermic people making poor decisions that were obviously wrong even to them in retrospect.