The Federal Aviation Authority has published draft rules to allow the routine commercial use of unmanned drones. But a key restriction means plans for delivery services will have to remain on hold.

The rules would mean that unmanned aircraft weighing less than 55 pounds could fly without special permission or licensing. However, the operator would need to be certified and pass an aeronautical knowledge test every two years. The drone itself would have to be registered, but officials would not inspect the plane for airworthiness: that would be the responsibility of the operator.

Flights would only be allowed during daylight hours, with a maximum airspeed of 100 mph and a maximum altitude of 500 feet.

The two big limitations are that the drone must remain within the line of sight of the operator (who must be able to see it without any special equipment such as binoculars), and that it cannot fly over anyone not involved in the operation. The FAA says it isn’t prepared at this stage to allow operators to rely on on-board first-person-view cameras to control the device.

Both of those mean plans by firms such as Amazon and Google to deliver goods by drone would be unworkable. (A Chinese firm has already tested drone deliveries to customers.)

The FAA says it’s open to discussion on the line of sight issue and is inviting feedback on the proposals. One possibility is that it might allow an operator to control the drone without being able to see it, as long as they are in contact with somebody who could. Another possibility is an exemption for drones below 4.4 pounds, though that would severely limit the goods that a delivery drone could carry.

[Image credit: FAA]