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2022: 5G Mobile Communications versus Aeronautical Radio Altimeters – Considerations from Aviation and Industry

FH-Prof. DI Dr. Holger Flühr, FH JOANNEUM

The given keynote can be downloaded here.


Already in 2018, ICAO technical committees discussed possible interference with radio altimeters (RA) caused by upcoming wireless systems on board aircraft as well as by future mobile communications. Detailed interference studies by a “5G Task Force” based in the Radio Technical Commission for Aeronautics (RTCA) on possible impairments of RA function by 5G NR in the C-band (3.70 – 3.98 GHz) revealed the existing risk of interference in all aircraft categories, up to the risk of a catastrophic failure. With the 2021 spectrum auction, the roll-out of 5G NR started in the USA. Several reports of RA malfunctions especially during the landing phase and under poor visibility conditions were published. As a result, the FAA published airworthiness directives (AD) for fixed-wing and rotary-wing aircraft and prohibited certain types of landing procedures based on RA data.

Although there are currently no known reports in Europe, the issue also negatively affects European airlines flying to airports in the United States. Also rescue flights as well as future flight operations within the framework of urban air mobility are equally affected, since high 5G NR field strengths can be expected especially in urban regions. The presentation will highlight both the technical principles of 5G NR as well as avionics using the example of radio altimeters and tries to explain the existing conflict potential as well as possible solutions.

Holger Flühr received his Dipl.-Ing. (M.Sc.) degree from the University of Karlsruhe (TH), Germany and his Dr. techn. (Ph.D.) degree from the Graz University of Technology, Austria. He worked as head of development in a leading company for passive and radio frequency components. Currently, he is a professor at FH JOANNEUM (University of Applied Sciences) in Graz, where he is responsible for teaching and research within the broad area of avionics and ATC technologies. At the Institute of Aviation, his current work focuses on passive radar technologies and future digital aeronautical communication systems. Holger Flühr is author or co-author of numerous scientific publications, contributions to internationally recognized conferences, and patent specifications. He has been involved in a number of projects related to aeronautical electronics including projects funded by Austrian Research Promotion Agency (FFG) or in collaboration with aviation industry.