SEATTLE: Amazon.com Inc Chief Executive Officer Jeff Bezos made a splash on Sunday with his radical plan to deliver goods to millions of its customers' doors by using a fleet of unmanned drones, but the bold vision is not likely to become a reality this decade.

By Bezos' own admission, the technology that would enable electric-powered 'octocopters' to fly to pre-programmed addresses unaided by humans is still early in development, and the United States is not likely to establish rules for civilian unmanned aircraft systems until 2015 at the earliest.

On top of that, the idea faces privacy concerns and was derided by some as merely a publicity stunt.

"I know this looks like science fiction. It's not," Bezos told Charlie Rose on CBS News' "60 Minutes" show on Sunday night, demonstrating video of a buzzing, toy-sized chopper delicately dropping a small package on a customer's patio.

The piece was aired on the eve of "Cyber Monday," one of the busiest online shopping days of the year when it helps Amazon to be on the minds of customers.

Dubbed "Prime Air" by Amazon, the vehicles could be used to deliver packages up to 5 lbs (2.3 kg) in less than 30 minutes within a 10-mile (16-km) radius of Amazon's so-called fulfillment centers, said Bezos.

"This is still years away... I don't want anyone to think this is just around the corner," said Bezos on "60 Minutes," acknowledging that the technology needs years of work, and the US Federal Aviation Administration won't likely have rules on unmanned vehicles until 2015 at the earliest.

But Bezos - renowned for his patience on long-term projects - said he was optimistic on making it a reality sooner rather than later.

"Could it be four, five years? I think so. It will work, and it will happen, and it's going to be a lot of fun," added Bezos.

Safety, privacy concerns

The idea of deliveries by unmanned vehicles is not completely new. Tech news site the Verge reported last month that Australian textbook rental firm Zookal plans to use drones to deliver books in that country next year, possibly expanding the service to the United States later.

But that company, and Bezos, are up against a raft of real-world challenges.

The UK-based Institution of Engineering and Technology (IET) immediately warned that the technology needs refinement.

"There are many challenges to overcome," said the IET's Lambert Dopping-Hepenstal, who is pushing for wider use of unmanned aircraft worldwide. "Top of the list is the need to mature the technologies and demonstrate to the regulators that unmanned aircraft can operate safely in our airspace."

US authorities have recognized the commercial applications of drones, but appear to be in no hurry to set the rules. The FAA currently only allows the use of unmanned aircraft systems (UAS) by public entities on a case-by-case basis.

"Over the next several years the FAA will establish regulations and standards for the safe integration of remote piloted UAS to meet increased demand," the FAA said in an e-mailed statement on Monday.

The FAA plans to begin tests on commercial UAS by the end of this year and to propose a rule for small craft next year, which means no firm regulations will be set before 2015. So far, only a single commercial UAS operator has been approved, in the Arctic.

Broader reaction to Bezos' plan was mixed.

Mark Udall, a Democrat Colorado senator who is pushing legislation that would outlaw domestic surveillance by UAS, raised concerns about privacy.

"Coloradans will accept this technology only if they are certain their privacy is protected and that Americans won't be victims of surveillance or privacy abuse by private unmanned aerial system operators," he said in a statement.

Richard Aboulafia, an aerospace industry expert and analyst at Teal Group, was more blunt.

"It's such an appallingly dumb idea that I presume they're talking about it as a form of clever satire," he said on Monday.