Last year saw temporary airport 5G restrictions imposed after safety concerns were voiced over potential interference with radio altimeters on airliners. A body representing the aviation industry has now called for these restrictions to be made permanent.

It’s the latest development in what began as an embarrassing clash between two different government agencies …

Background

Widespread adoption of cable and fiber-based TV services saw the effective demise of satellite TV. That meant that the frequencies previously used for those broadcasts could be freed-up for alternative use.

The usage of radio frequencies is controlled by the Federal Communications Commission (FCC), which decided that the frequencies were suitable for 5G use, and auctioned off the rights to use them. Verizon and AT&T jointly spent $68M on acquiring the rights to what was then labeled 5G C-band.

Another government agency, the Federal Aviation Administration (FAA), appeared to discover this fact after the event. It said that there was a risk of 5G C-band spectrum interfering with radio altimeters.

Radio altimeters on board airliners and some other aircraft bounce a radio signal off the ground and time the return signal to determine the altitude of the plane. This is much more accurate than pressure-based altimeters, and is used during the final approach and landing. It plays an especially important role in conditions of poor visibility.

The FAA had been voicing concerns about the potential risks of C-band interference since 2015, but it seems that the agency didn’t directly communicate these to the FCC until very late in the day.

The result was a very public and embarrassing argument between the two. It did seem clear that only older radio altimeters were at risk, and there was limited evidence even for these. After a series of proposed delays and compromises, an eventual deal was done, imposing temporary 5G C-band restrictions around 50 major airports. This gave the aviation industry until July 2023 to check their older aircraft, updating radio altimeters as required.

Airport 5G restrictions could be made permanent

However, a body representing the aviation industry has now called for the restrictions to be made permanent.

A letter has been sent to the FCC by a legal firm representing Aviation Spectrum Resources, Inc. (ASRI) – which was itself representing the views of a wide range of aviation bodies and businesses that met with the FCC earlier this month. Namely:

  • Aerospace Industries Association
  • Airlines for America
  • Air Line Pilot Association International
  • American Airlines
  • ASRI
  • Collins Aerospace
  • Regional Airline Association
  • Garmin International
  • National Air Carrier Association
  • Thales

The letter notes that the temporary restrictions do not appear to have had any downside, and asks for some of them to be made permanent.

Verizon told CNET that it was continuing its discussions with the FCC, “and progress is being made.” The carrier didn’t directly comment on the ASRI letter.

Preventing antennas pointing 90 degrees above the horizon, and maintaining the wireless spurious emissions in the 4200-4400 MHz band consistent with current mitigations, would appear to not compromise wireless operators’ actual use cases while further assuring aviation safety and providing a workable RF environment against which future radio altimeters can be designed and built.

Photo: Dragoș Grigore/Unsplash