"Perched impossibly on a ridge overlooking a 10,000-foot drop into Tibet, Sano Babu Sunuwar and Lakpa Tsheri Sherpa wait. Heel to toe, connected at the waist by a pair of carabineers that's connected to nothing else, they stare down the North Face of Mount Everest, a red and white nylon tandem paragliding wing fluttering behind them.