Last year, Boeing and Airbus asked the U.S. authorities to postpone the deployment of 5G networks in the C-band because of fears that they might compromise the safety of air communications, a concern that was supported by the U.S. Federal Civil Aviation Authority published a study that found that 5G networks in the C-band did not affect the functioning of sensitive aircraft electronics.
In the course of the NTIA study, aircraft with radio altimeters were used to operate in the C-band; the equipment was tested in real-world conditions on three types of 5G cellular towers used in the infrastructure of the United States telecommunications companies AT&T and Verizon; radio altimeters usually use frequencies ranging from 4.2 GHz to 4.4 GHz; and base stations 5G C-bands range from 3.7 GHz to 3.98 GHz.
In May last year, FAA called on airlines to equip aircraft with radio altimeters with special filters, which the regulator believed should have ruled out the possibility of interference. So far, 90% of commercial aircraft in the United States have installed filters and obtained flight clearance.
The NTIA report states that the FAA filters are operating, the current disturbances are too weak to influence aircraft instruments, and the 5G towers are designed so that most of the signal is transmitted in parallel to the ground rather than up. It is also noted that 5G stations have frequency cuts that prevent them from exceeding 4.0 GHz during operation. According to researchers, unwanted emissions from 5G towers can be minimized even more.
In general, the 151-page NTIA report can be summarized as the only statement: . Simply put, the agency has determined that planes with radioaltimers and 5G stations can survive together if the necessary security measures are taken.