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Drones in cities: balancing big benefits against real dangers


BRUSSELS – The mainstream media may have missed it, but an extraordinary event recently occurred in aviation history.

From mid-March to early April, Swiss Post and drone developer Matternet completed 70 test flights of a remotely piloted aircraft system (RPAS) between two hospitals over the city of Lugano, Switzerland. The drones flew a bit less than two kilometres, a bit beyond an operator’s line-of-sight, and carried laboratory samples. The flight was automated, although a remote pilot remained on stand-by in case of a malfunction.

Aviation observers believe these flights may have been among the world’s first sanctioned uses of a commercial drone over an urban area.

At an April 7th workshop at Eurocontrol’s HQ here, drone practitioners and experts greeted the news with excitement, but also trepidation. For the vast majority of regulators and commercial operators, recreational drone use in urban areas remains, and will remain, taboo. But the security-related and commercial potential of ‘urban drones’ remains enormous in activities ranging from crisis response and policing to taking outside pictures of high-rise apartments for the real estate market.

First off, urban areas are treacherous places for any aircraft. The streets between buildings are like canyons, where wind gusts and unexpected turbulence can throw a large craft off course, or even bring it down. Immediate weather conditions can vary without warning.

For relatively lightweight drones, these dangers are multiplied. Tall buildings can scramble or block the GPS signal upon which most drones depend. Urban drones must also avoid conflict with other denizens of the air, including helicopters and even flocks of birds. If one fell from the sky, it would need a parachute to help it land without incident — assuming the chute opened properly. Where it fell would depend upon where it was allowed to fly: over a city river, for example, or a park, or a major highway.

Operators shook their heads when they considered the obstacles. “If you have UTM [Unmanned Aerial Vehicle Traffic Management] in a city, then the UTM should be flying the plane, and not the person,” one expert said. Another commented: “A small street, from a meteorological point of view, is completely different from a wide street” and would necessitate a different flight path. “All systems rely on GPS signals, but GPS can have issues.

The thought bounced around the table: What does a drone do when it loses its signal? Just hover? And for how long when the maximum battery time for large copter-drones can be half an hour?

One operator discussed how the definition of ‘line-of-sight’ becomes blurred in an urban environment. “If a professional sees a dot in the sky, it means VLOS [visual line of sight],” he said. “But [in an urban environment]…if a large truck comes down the street, you don’t see the drone anymore.”

Other issues discussed included ‘separation’ versus ‘segregation’. Would drones keep their distance by simply separating themselves in the air, automatically? Or would temporary segregation give a drone the exclusive right to a corridor of airspace during certain hours or minutes of the day?

Other sessions during the workshop tackled drones that operate beyond the visual line of sight (BVLOS). A few countries — including France, the UK, Spain, and the Netherlands — are testing or experimenting with BVLOS drones. Australia is actually doing it, deploying BVLOS drones that can travel a distance of many kilometres above 500 feet, descending to inspect a site such as a mine and then climbing above 500 feet for the trip home. But one operator from Australia mentioned problems with drone cybersecurity. “We’ve had numerous examples of people trying to hack into the vehicle and take it over,” he said.

The conference concluded with discussion of the potential safety requirements for urban flight. These should include a safety risk assessment and redundant systems, particularly for C2 communications, along with hard-and-fast rules for a variety of scenarios. In the same vein, emergency procedures must allow for safe landings in the event that a drone plunges from the sky. Finally, remote pilots must be sufficiently trained to take over an automated drone at a moment’s notice.

As for BVLOS flight, participants grouped the requirements into ‘segregated’ drones (i.e., those with exclusive flight paths) and ‘non-segregated’ ones. Segregated BVLOS drone flights should meet a risk assessment, with their status determined on a case-by-case basis. Non-segregated flights — which could potentially come much closer to one another — would require a longer list of requirements, including airspace and risk assessments, flight notification and planning, licensed pilots, and dedicated unmanned aerial vehicle traffic Management.

     THE UPSHOT: To a person, workshop participants stressed the need to ‘get it right’ regarding urban drones, with multiple redundant systems reducing to zero the chance that a large commercial drone could fall on someone’s head. But as seen in the commercial flight industry, no matter how many redundant systems are put in place, catastrophic failure will happen anyway.
     Big planes fall out of the sky, and people die. So will it be with urban drones, although the overall benefit will still be positive as the Lugano drones’ life-saving delivery of laboratory results clearly showed. The best solution will be risk management. But industry has to be realistic about this: talking less about “never failing” and more about what to do when failures occur.
     Another problem here, as with other drone issues, will be the junction where UTM intersects with traditional ATM. In urban areas, UTM would be mostly automated, with a pre-designed flight path punched into the drone, with a trained pilot on stand-by. One workshop participant suggested that above 500 feet, ATM would ‘take over’ the drone. But it’s hard to imagine ATM workers assuming command of a drone that pops up on their screens at a moment’s notice. Presumably, they have enough work to do in cities with large airports nearby. Safe to say, issues surrounding urban UTMs will probably remain a hornet’s nest for years to come.


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