The experimental airworthiness certificate gives the online retail giant an opportunity to begin testing a design that one day could lead to a delivery network of drones.

Share story won approval from the Federal Aviation Administration (FAA) to test a specific drone design outdoors that the company hopes will lead to the deployment of a drone-delivery system.

On Thursday, the FAA issued a so-called “experimental airworthiness certificate” to a design that Amazon Logistics had submitted for approval. The certificate allows Amazon to conduct research and development on the submitted drone design and train a crew to fly the craft.

Amazon Chief Executive Jeff Bezos unveiled the company’s drone-delivery plans just before the holiday-shopping season in 2013 in an interview on CBS’s “60 Minutes.” At the time, Bezos said drones would carry as many as 5 pounds within a 10-mile radius of an Amazon warehouse, aiming for delivery within 30 minutes.

“It will work, and it will happen, and it’s gonna be a lot of fun,” Bezos told CBS’s Charlie Rose.

Bezos estimated that the company could start using drones within four to five years, pending FAA approval.

Since then, though, Amazon has been frustrated by the agency’s process. The FAA proposed rules in February on the commercial use of small drones, that requires companies to fly only during daylight and keep their drones in sight. The proposal began a process that could take as long as two years to come up with final rules regarding commercial-drone use.

When those rules were proposed, Paul Misener, Amazon’s vice president for global public policy, criticized the agency’s slow pace.

“The FAA needs to begin and expeditiously complete the formal process to address the needs of our business, and ultimately our customers,” Misener said. “We are committed to realizing our vision for Prime Air and are prepared to deploy where we have the regulatory support we need.”

In December, The Wall Street Journal reported that Misener threatened in a letter to the FAA that Amazon would move its drone development to the United Kingdom, which has more relaxed rules regarding drone flight. Amazon has already tested drone designs there.

Amazon didn’t immediately respond to questions about the new certificate from the FAA. Under the provisions of that certificate, Amazon is required to keep all flight operations below 400 feet, and it must conduct them during daylight hours. The drone must remain within site of the pilot and an observer. And the pilot must have a private pilot’s certificate, as well as current medical certification.

The agency is also requiring Amazon to provide monthly data reporting the number of flights conducted, pilot duty time per flight, unusual hardware or software malfunctions, any deviations from air traffic controllers’ instructions and any unintended loss of communication links.