Back in 2013, when Amazon boss Jeff Bezos unveiled his Prime Air plan for deliveries using drones, many observers assumed the idea was more "publicity stunt" than "serious effort to improve customer service."

But as time went on, Amazon continued talking about its ambitious plan, investing huge sums in related research and development, and putting pressure on the authorities to grant it more freedom to test its technology.

Nearly three years on and most people now accept that the e-commerce giant may one day achieve its dream of a nationwide drone delivery system, its autonomous flying machines criss-crossing communities, getting customers' orders in their hands in under 30 minutes.

Stumbling block

One of the major stumbling blocks for Amazon's plan -- and others like it -- is a Federal Aviation Administration (FAA) stipulation that drones have to stay in the line of sight of the operator at all times.

Of course, this makes it impossible for a drone to fly for more than a few minutes in a single direction, unless the operator is following behind in a vehicle, which would rather defeat the whole idea. And it completely ignores the idea of autonomous drones using built-in technology and GPS to safely fly a pre-programmed route.

In that case, Amazon is hoping for the speedy creation of a nationwide drone-based air traffic control system, something that a number of companies are already working on developing.

In fact, an FAA decision in recent days giving permission -- for the first time ever -- to a company to fly its drones beyond the sight of its operator comes thanks to air traffic control technology.

PrecisionHawk, which manufactures drones mainly for agricultural use, has been given the go-ahead to use its fixed-wing flying machines on farms.

To ensure safe flight, operators use what PrecisionHawk calls a "low altitude traffic and airspace safety system," or LATAS, to enable its drones to automatically avoid other air traffic and obstacles encountered while in the air.

"In agriculture, now that we have an exemption to fly beyond the visual line of sight, we can fly an entire farm, not just one field, efficiently," PrecisionHawk EVP Thomas Haun told TechCrunch.

The company will still have to fly in accordance with other rules as laid out by the FAA in a recently released framework, including keeping away from crowds and flying only during daylight hours, but it's nevertheless a notable step forward for the drone industry.

While Amazon's proposed service is unlikely to be green-lighted by the FAA anytime soon, especially if the company wants to take its drones into built-up areas, this recent development is at least a sign that the FAA is willing to seriously examine applications offering new technology-based solutions.

Amazon likes to start small with new services, so if it can find a location that ticks all the safety boxes, including the use of an effective drone-monitoring system, perhaps the FAA will be persuaded sooner rather than later to allow the company's first-ever Prime Air drone delivery.