Drones used for first time in major search at Grand Canyon

PHOENIX — The desperate effort this week to find two hikers who disappeared at the bottom of the Grand Canyon represented the National Park Service's most extensive use yet of drones in a search-and-rescue mission.The Grand Canyon is the only national park with its own fleet of unmanned aircraft for reaching people who have gotten lost, stranded, injured or killed. Under a program that began last fall, it has five drones and four certified operators.While the aerial search for the two hike