For years, there's been a cardinal rule for flying civilian drones: Keep them within your line of sight. Not just because it's a good idea — it's also the law.
But some drones have recently gotten permission to soar out of their pilots' sight. They can now inspect high-voltage power lines across the forested Great Dismal Swamp in Virginia. They're tracking endangered sea turtles off Florida's coast and monitoring seaports in the Netherlands and railroads from New Jersey to the rural West.
