The drones circled over the caves and crevices scattered around the mountain trails in northern Utah, feeding real-time video back to a search team on the ground looking for a missing hiker. Nineteen minutes later, they had her coordinates, bringing the rescue – a drill – closer to conclusion.

“In this kind of environment, that’s actually pretty quick,” said Kyle Nordfors, a volunteer search and rescue worker. He was operating one of the drones, made by the Chinese company DJI, which dominates sales to law enforcement agencies as well as the hobbyist market in the United States.