The concept was an instant, albeit theoretical hit, but progress has proved slow due to regulatory red tape at the Federal Aviation Administration. The tension between federal regulators and the e-commerce giant came to a head in March, when Paul Misener, Amazon’s vice-president for global public policy, told US lawmakers that Amazon had begun quietly testing its prototypes in other countries.

Misener’s rebuke came in response to news that the FAA had granted Amazon permission to test its octocopters. The problem? The permission had been so long in coming that the proposed drone technology had since become obsolete.

“We don’t test it any more. We’ve moved on to more advanced designs that we already are testing abroad,” Misener said, according to The Guardian. “Nowhere outside of the United States have we been required to wait more than one or two months to begin testing.”

Now, Amazon has officially received permission to test the new drone prototype. In a letter posted on the agency’s website Apr. 8, the FAA wrote that the testing could move forward, with a few stipulations: the drones cannot fly higher than 400 feet in the air, faster than 100 miles per hour, and must always remain within the operators line of sight.

That last restriction is important, as it represents perhaps the biggest stumbling block currently to Bezos’ ambitious vision of a drone that could deliver packages distances of at least 10 miles, in densely-populated urban areas.

But while Amazon Prime’s reportedly tens of millions of members shouldn’t expect drones dropping in on their doorsteps anytime soon, this latest move suggests the FAA is finally taking the future potential of commercialized unmanned aerial vehicles more seriously.

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