Nothing rattled Keith Echelmeyer. Come back from rappelling into blue glaciers in Antarctica, teach a university class the next day. Crawl out from a plane crash with a broken leg, head to Greenland in a cast the next week. Bag an iconic Alaska peak for a first winter ascent over the weekend, stroll into work on Monday. He flew his single-engine plane like most of us drive cars. The mileage of his glacier flights equalled a few trips around...