Satellites replace radar: Initial tests under way

The US Federal Aviation Authority (FAA) predicted five years ago that there would be some 15,000 drones in the USA by the year 2020. In fact, unmanned aerial vehicles have spread at a much faster rate: At present, 15,000 drones are sold in the USA every month. By late 2014, Deloitte consultants were already predicting that the base of commercial and private drones would exceed one million units by year-end 2015. The CES electronics trade show in Las Vegas counted 26 different exhibitors of unmanned aerial vehicles in 2016, as opposed to only four in 2014.  Although the market for passenger aircraft is developing only moderately in comparison, its growth is still continuous. According to aircraft manufacturer Boeing, the number of aircraft in operation has nearly doubled over the last twenty years to 24,000, while flight hours total 56.5 million per year. This trend is set to continue over the next twenty years.

Mr. Küsters, as different as drones and passenger aircraft are in appearance, both kinds of aircraft – unmanned and manned – are to be subject to similar technical requirements in just a few years' time. Why is that?

The reason is that the European-wide standardisation of air traffic management through SESAR, and its US counterpart NextGen, are going to take effect starting in 2020. Their primary objectives are to make airspace safer, manage it more efficiently and reduce emissions. The Airborne Collision Avoidance System X (ACAS X) plays an important role in this context. It is the first collision avoidance system to exchange data via satellite. The advantage is that all aircraft equipped with this technology automatically avoid each other, without pilot intervention. This is not yet possible at present. ACAS II, the predecessor, although considered very safe, still operates with radar technology. Today, if one aircraft avoids another, the pilot reports the manoeuvre to ground control by radio. Soon, that will no longer be necessary, because ground control will receive the information automatically. One important change in 2020: Even unmanned aerial vehicles, such as drones and small aircraft, will be required to use ACAS X – a critical decision for making airspace safer. 

In the coming year, Amazon and Google are already planning to use drones to make deliveries. Various logistics companies are working on similar concepts. How can this increasing traffic be reliably controlled?

It will be important to reserve flight corridors for package delivery by drones, but also to define no-go zones. As soon as unmanned aircraft enter these off-limit zones, a virtual fence, referred to as a “geofencing” system, calls them back. With a system like this, the drone that crashed directly behind Austrian skier Marcel Hirscher during a downhill competition would never have come into the vicinity of the slope. Starting in 2020, ACAS X will additionally ensure that collisions are avoided and that airspace used mostly by unmanned aircraft remains safe. What is certain is that government authorities will not permit drones in air traffic to any major extent unless safety can be ensured.

Together with satellite-based communication, web-based data exchange, for instance between ground control and the pilots, is playing an increasingly important role. What are the implications of this development and how will it affect the security of the systems?

Until now, closed, proprietary systems have mainly been in use. Their disadvantage is that information is exchanged between systems indirectly at best. The goal of harmonising air traffic management under the plans of SESAR and NextGen requires open standards. In practice, this means for instance that ground control crews can communicate via satellite with pilots. This type of satellite-based air navigation currently is being tested in Canada and Alaska. Currently, errors occur in transmission. In addition, “system-immanent” weaknesses are observed, caused by hardware or software errors, or by electromagnetic and atmospheric influences. On top of that we are seeing potential external threats. For example, a recent cyber threat analysis in the USA showed that flight control systems in aircraft, meaning navigation devices, aircraft management and autopilot – as well as flight management at ground control stations are particularly vulnerable to hackers. What happens when aircraft calculate the wrong route or satellite data are manipulated? In the aviation sector, as in the automotive industry, it still is unclear who can be held responsible for a successful cyber attack. Is it the system or component manufacturer? Or is it the seller or owner? Scandinavian car maker VOLVO recently took the first step, claiming full liability for its products as the manufacturer. The aviation industry will also have to answer this question, at the latest by 2020. But before they do, the corresponding Galileo and GPS II satellites must first be put in orbit for these new services to go into operation.