Since the invention of the Remote Tower concept by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in 2002, the idea has made great progress and is now being used for remote air traffic control, initially at small airports in Sweden and Germany. DLR researchers and their international partners have carried out simulations to investigate how a single air traffic controller can control not just one, but multiple airports. “The successful test campaign and its recent results have shown that ‘multiple’ can become a viable concept in the near future,” says Jörn Jakobi from the DLR Institute of Flight Guidance, who is DLR’s Project Coordinator for the European research project ‘PJ05 Remote Tower for Multiple Airports’. Research is opening the door to a paradigm shift for aerodromes air traffic control, when more than one aerodrome is controlled from a single controller working position.
Controlling more than one airport at a time
Remote air traffic control of a small airport can have several benefits. For example, maintenance and operating costs can be reduced and poor visibility conditions can be compensated for by modern camera technology. But to take full advantage of the Remote Tower concept, remote tower centres must be connected to more than one airport. This allows a much more efficient allocation of airports to air traffic controllers. The controllers work flexibly at airports where there is air traffic. In more complex traffic situations, one, two or more controllers can control a single airport, while in less intense traffic situations a single controller can be responsible for one, two or more airports. “Small and regional airports are faced with the challenge of reconciling the high costs of operating an efficient air traffic control tower with the low revenues from landing fees and other flight-related charges when traffic throughput is scarce or only temporary,” explains Jakobi. “The collective control of several airports offers the opportunity for the smaller ones to survive at low cost.”
Whether and under what conditions air traffic controllers can serve more than one airport at the same time raises numerous technical and human factors related questions for researchers and industry. Since 2016, 37 international partners led by the DLR Institute of Flight Guidance in Braunschweig have been researching solutions within the framework of the EU research and innovation programme Horizon 2020. Together with DLR’s partners Frequentis AG, Leonardo Germany GmbH, the Hungarian Air Navigation Service Provider (ANSP) HungaroControl and the Lithuanian ANSP Oro Navigacija, four simulation experiments were conducted at the DLR Remote Tower Laboratory in Braunschweig from November 2017 to December 2018. In the tests, one controller handled the traffic for up to three airports simultaneously.
The participants were confronted with different weather scenarios, changes of runway direction, runway inspections and emergency situations. They had to carry out coordination tasks with the approach controllers, the weather service and the airport operators. Depending on the complexity of the traffic situation, the controllers’ workload can range from totally underloaded to totally overloaded. Both extreme ends happen and should be avoided. ‘Multiple’ addresses this problem by a new ‘split and merge’ procedure. It allows the controllers to split or merge airports between different working positions. The feedback from the controllers indicates that this procedure shows great promise as a way of coping better with the workload in under- or overload situations. “After the trials, the controllers reported that they were able to quickly and easily familiarise themselves with the new concept,” says Jakobi. “They did not experience a single situation in which safety was impaired during all the simulation runs, and were therefore confident that the ‘Multiple Remote Tower’ could become a viable concept in the future."
The invention of the Remote Tower
The idea of a remote or ‘virtual’ tower was first formulated in 2002 by DLR as part of an internal competition for innovative technological ideas. The idea won the competition, and in 2005 the world’s first remote-controlled tower prototype was set up by the DLR Institute of Flight Guidance at Braunschweig Wolfsburg Airport to test the technical and operational feasibility of the concept. This was followed by several national and international research and development activities, and numerous air traffic control organisations, such as the Swedish civil aviation authority (LFV) and the German air traffic control service (DFS), showed interest. In 2014, DLR carried out a technology transfer to industry. In 2015, the first Remote Tower installation in Sweden commenced operations, controlling Örnsköldsvik airport from Sundsvall.
DFS also opted for remote control of the Saarbrücken, Erfurt and Dresden airports from a Remote Tower centre in Leipzig, a concept first tested for safety and operability in a Remote Tower Lab at DLR Braunschweig in a simulation environment. The positive results supported this concept and since December 2018, Saarbrücken, the first airport remotely controlled by DFS, has been in operation. Erfurt and Dresden will follow in the next few years.
The ‘PJ05 Remote Tower for Multiple Airports’ project started in 2016 and will run until 2019. It receives funding from the SESAR Joint Undertaking within Horizon 2020, the European Union Framework Programme for Research and Innovation (grant no. 730195). Further project information can be found on the project homepage: www.remote-tower.eu