Firefighters are battling to control a series of major fires in the Los Angeles area that have killed five people, ravaged communities from the Pacific Coast to Pasadena and sent thousands of people frantically fleeing their homes.

In the aftermath the FAA promised severe punishment for anyone caught flying drones in a way that interferes with firefighting, with penalties of up to 12 months in prison and $75,000 in fines. But the uncomfortable reality is that there is little that authorities can do to prevent illegal drone flights,