5G still disrupts 1,000 planes in the United States

Civil aviation in the USA gives airlines one year to adapt to 5G. 1,000 planes need to be upgraded.

A year. This is the deadline that the Federal Civil Aviation Administration (FAA) plans to give airlines to put an end to interference between 5G and planes. As of February 1, 2024, aircraft must have benefited from an overhaul to make them insensitive to the frequencies used in the USA for the new generation of mobile telephony.

This upgrade affects one in eight aircraft in the United States, according to FAA estimates in a document highlighted by Ars Technica on January 10. There are nearly 7,000 aircraft on the US registry that is already equipped to filter 5G on their devices (or are in the process of being equipped). But there are still a good thousand to update.

Interference between radio altimeters and 5G

The problem lies with the radio altimeter. This device is used by an aircraft to assess its altitude relative to the ground, via the emission and reception of radio waves. It is an important tool during a sensitive phase of the flight, which is landing because it helps the crew to determine the correct trajectory of the aircraft in relation to the runway, in particular at night or in bad weather.

According to the FAA, there are 180 aircraft in need of altimeter replacement. As for the remaining 820 planes, filters should be enough to prevent 5G from disturbing the onboard instruments. All of this will come at a cost to airlines, estimated at just over $26 million ($26,000 per aircraft on average).

“Some radio altimeters can already demonstrate tolerance to 5G C-band emissions without modification,” comments the FAA. “Others may need to install filters between the radio altimeter and the antenna to increase the tolerance of the radio altimeter.” Those for whom this measure will be insufficient will have to be replaced by a more efficient model.

The FAA estimates the number of aircraft suitable for the arrival of 5G at 7,000. But there are a thousand more in need of an update. // Source: Olivier Cabaret

The difficult coexistence between 5G and radio altimeters is caused by the significant proximity between the two uses. 5G in the USA uses a band called C, which ranges from 3.7 to 3.98 gigahertz (GHz). However, not far away is also a band that is used for the air sector, in particular for communication. This band goes from 4.2 to 4.4 GHz. There is barely a 200 MHz difference.

In Europe, this problem does not really exist: first, the difference is greater (400 MHz). Then, additional arrangements were made. In this case, the signals from the 5G antennas were directed downward in the vicinity of major airports. Thus, air traffic is less affected by the arrival of mobile ultra-high speed.

Other rules have also been put in place to modulate the power of the waves according to the location of the antennas at the airports (there are thus two zones, one for security and another for precaution). In addition, the radio altimeters are also updated if necessary. The risk of interference is therefore much lower on this side of the Atlantic.


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