Amazon has moved a step closer to its goal of one day delivering packages by drone. The Federal Aviation Administration on Thursday issued an “experimental airworthiness certificate” to Amazon, allowing the company to test its unmanned aircraft. The certificate comes with some restrictions. Amazon will only be able fly its test drones during daylight in clear conditions. Drones can't fly out of sight of the pilot, who must have a private pilot’s certificate, and an observer. The company's drones are also not allowed to fly higher than 400 feet above the ground.

Amazon CEO Jeff Bezos first announced the company's Prime Air project while on "60 Minutes" in December 2013, but its plans were soon deflated by the FAA. In China, Amazon already has some competition, as online retail giant Alibaba is testing drones that deliver tea.

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Amazon moves one (tiny) step closer to drone delivery thanks to a special certificate from the FAA http://t.co/iI1uTta7G8 — Rebecca Borison (@borisonr) March 19, 2015

Amazon just got permission from the FAA to start testing its delivery drones in the US http://t.co/Fgoto1w7sL pic.twitter.com/uT2DvcUdtQ — The Verge (@verge) March 19, 2015

— Keith Wagstaff