Interviews

“Lower frequency bands are used in Switzerland.”

For some time, the US aviation industry has warned about the potential hazards to air traffic posed by interference between aircraft technical systems and 5G transmitters. In the United States, there are fears that these frequencies could disrupt aircraft altimeters. We discussed the situation in Switzerland with Peter Fritschi, Swisscom’s expert in the measurement of non-ionising radiation.

By Armin Schädeli

21 January 2022

Peter Fritschi, in the US, there are fears that 5G mast frequencies might interfere with aircraft altimeters, giving rise to hazardous situations. Is this possible?

First off, this is not so much an issue of different mobile generations such as 5G or 4G but rather the frequencies in use. Aircraft altimeters operate in a frequency range of between 4.2 and 4.4 GHz. In the US, 5G technology has been authorised to operate in the 3.75-3.98 Ghz frequency range, giving rise to fears that it could interfere with aircraft radio altimeters. Of course, it is not for Swisscom to assess the situation in the US. According to the Federal Office of Civil Aviation, no interference has occurred to date in this country and the situation in Switzerland is not comparable to that in the US. The Federal Office of Civil Aviation (FOCA) states that, to date, there have been no incidents recorded anywhere in the world in which 5G masts have led to the impairment of aircraft safety functions.

What is the situation in Switzerland?

Swisscom has acquired frequencies between 3.58 and 3.7 GHz. Adaptive antenna array systems transmit within this frequency range and are thus below the US values. This means that there is a greater margin of safety. Moreover, due to strict installation limit values, our antennas are restricted in their performance in comparison to American systems. OFCOM[1] and FOCA[2] are taking the issue seriously however, and we are in contact with the relevant authorities and federal offices.

At European level, a study has been commissioned into whether interference could occur. What does this mean for Switzerland?

While there is no indication at present that the frequencies used for 5G interfere with aircraft altimeters, it is nonetheless sensible for detailed expert investigations to be carried out into the issue. Ultimately, we all want safe aviation – from the public authorities to the mobile providers and above all, of course, the passengers.

Would Swisscom act if evidence of a threat were found?

This is, of course, a hypothetical question. There is currently no evidence to point to that. However, in such circumstances, the public authorities would of course react, and we would follow their guidelines. What is it they say in the aviation industry? Safety first!

[1] Federal Office of Communications
[2] Federal Office of Civil Aviation

Peter Fritschi

Experte für die Messung von nichtionisierender Strahlung und Innovation, El.-Ing. HTL/MBA

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