A Parallel Air Traffic Control System Will Let Delivery Drones Fly Safely

Engineers are figuring out how to let drones fly beyond visual range

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In 2013, shortly before Christmas, Amazon.com released a video depicting its plans to speed packages to their destinations using small drones. Some commentators said it was just a publicity stunt. But the notion began to seem less far-fetched when Google revealed its own drone-based delivery effort in 2014, something it calls Project Wing. And in the early months of 2016, DHL actually integrated drones into its logistics network, albeit in an extremely limited way—delivering packages to a single mountaintop in Germany that is difficult to access by car in winter.

“It started to get momentum after serious players came in,” says Parimal Kopardekar, NASA’s senior engineer for air transportation systems, who has been researching ways to work these buzzing little contraptions into an air traffic control system created for full-size aircraft. “We need to accommodate drones.”

This past August, the U.S. Federal Aviation Administration (FAA) introduced Part 107, also known as the Small UAS Rule, which allows companies to use small drones in the daytime (or during twilight) and within visual line of sight of the pilot, so long as they are not flown over people who aren’t participating in these operations.

This year promises to see the FAA’s drone rules loosen even more. At the InterDrone conference in Las Vegas this past September, FAA head Michael Huerta explained that his agency was drafting rules to allow drones to be flown over random bystanders (the FAA calls them “non-participants”) and that it plans to release proposed regulations to that effect by the end of 2016. “We’re also working on a proposal that would allow people to fly drones beyond visual line of sight,” he said. Such a move would open the door to the use of small drones to deliver packages, among other things.

Of course, when you start flying drones where you can’t see them, you need to put technology in place to be sure that they don’t hit anything or injure anybody. While the details of how exactly to do that remain to be hammered out, there is no shortage of ideas.

One of the companies working on this challenge is PrecisionHawk, based in Raleigh, N.C. It’s one of just two companies to have obtained a waiver from the FAA allowing it to fly small drones beyond the operator’s visual line of sight. For such flights, the FAA does, however, require that an observer be posted to look out for full-scale aircraft.

Still, the waiver increases the range of the company’s drone operations from how far away you can see a small aerial vehicle—typically a kilometer or less—to how far away you can see a full-size plane—6 to 7 kilometers. The waiver does not allow “a 200-mile straight-line flight from A to B,” notes Thomas Haun of PrecisionHawk. Nevertheless, he’s heartened by the “much broader area” the exception permits. The engineers at PrecisionHawk obtained that waiver in part because it had created a system to help drone pilots safely operate a vehicle that they can’t directly see.

Avoiding a collision with a full-size aircraft is job No. 1, of course. But the more typical danger is much more mundane—running into a tree or a wall. To avoid that, PrecisionHawk uses satellite imagery to create a detailed terrain model, one of sufficient resolution to capture how high each tree and building is. Its system continually updates that model as new satellite imagery becomes available. Flight-planning software or even the autopilot on the drone itself can then use this information to avoid obstacles.

PrecisionHawk has also worked out a mechanism for drone operators to get updates through Verizon’s cellular network on the location of full-size aircraft—the same sort of information that air traffic controllers have. And PrecisionHawk’s drones report their positions over that same wireless network, so air traffic controllers and pilots can, in principle, know where these machines are. “What we’re providing as a product is primarily the software and data,” says Tyler Collins, the creator of this system, which goes by the acronym LATAS (Low Altitude Traffic and Airspace Safety). “We want LATAS on every drone.”

PrecisionHawk’s system mimics the strategy that is increasingly being used to manage full-size aircraft, whereby those aircraft determine their positions using GPS or some other form of satellite navigation and broadcast that information by radio to everyone else. The equipment for this form of air traffic management, called ADS-B (for Automatic Dependent Surveillance-Broadcast), will be mandatory on most U.S. aircraft by 2020.

While it might seem sensible to include small drones in the upcoming ADS-B regime, doing so could easily overwhelm that system, given the huge and growing number of drones—they’re selling at a rate of about 2 million a year in the United States alone, according to the FAA [PDF]. With those numbers growing so fast, an independent scheme for drone-traffic management seems inevitable.

NASA, Google, and Amazon have all been contemplating what such a system should entail. While the concepts that have been outlined vary in many ways, they are all similar in that they would restrict drones to the first few hundred feet above the ground and to locations that are well separated from any airports—that is, to parts of the sky full-size aircraft rarely visit.

At an airport in Reno, Nev., this past October, NASA and various industry partners carried out trials meant to help establish detailed technical requirements for a drone traffic-management system, one that would allow deliveries like the one depicted in that 2013 Amazon video. So whether or not it was a publicity stunt, perhaps this indeed is what the future holds. Haun of PrecisionHawk says, “We actually don’t think the future is very far off.”

This article appears in the January 2017 print issue as “Air Traffic Control for Delivery Drones.”

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