US proposes drone rules for commercial use

The Federal Aviation Administration proposed requirements that commercial operators must meet, such as passing a knowledge test administered by the agency as well as a federal security check, in order to fly small drones, defined as weighing less than 25kg.

It's likely to be two or three years before the rules are made final, but federal officials said once they are in place the economic and safety benefits of unmanned aircraft are expected to be enormous.

Among the chores that officials envision drones performing: Aerial photography and mapping, crop monitoring, and inspections of cell towers, bridges and other tall structures. But the proposal includes safety restrictions such as keeping drones within sight of operators at all times and no night flights. Drones would also have to stay at 8km away from an airport.

Flights over people except those involved in the drone's operation would be prohibited.

They could travel as fast as 160km/h, but flights would be limited to 150m in altitude or below. Flights over crowds would also be prohibited.

The agency is researching technology that he hopes will eventually enable small drones to fly safely beyond the sight of operators, Huerta said.

He emphasised introduction of commercial drones into the national airspace will be a staged process.

The government is also looking ahead to how larger drones might be allowed to fly in airspace shared by manned aircraft, for example, he said.

One of the key safety concerns is that without a human on board the ability to "see and avoid" other aircraft is limited. Another concern is the link between the operator and a remote control aircraft can be broken, causing the drone to fly away until it loses power or collides with something.

Cases of flyaway drones getting stuck in trees or hitting buildings are rampant. Last month, a drone that its operator lost control of flew over the White House fence and crashed on the lawn before Secret Service agents could block it.