Amazon's drone delivery plans appear to have been shot down by U.S. regulators, who have proposed new rules that would require operators to keep the flying machines in their line of sight. The Federal Aviation Administration (FAA) said that operators of commercial unmanned aircraft would need to see the drone with "unaided vision," in draft rules published on Sunday. It also said that small drones must not fly over people – denting Amazon's plans for its Prime Air drone delivery service.

The FAA is now consulting with the public and interested parties, and stressed that the rules would be flexible, giving hope that future revisions to the rules that could benefit companies planning to use drones for commercial purposes. "We have tried to be flexible in writing these rules," FAA administrator Michael Huerta said in a statement. "We want to maintain today's outstanding level of aviation safety without placing an undue regulatory burden on an emerging industry."