UPDATE After all the noise from aviation quarters last week about 5G on C-band when AT&T and Verizon launched their new service, things seem to be settling down. That’s because the FAA says it cleared 78 percent of U.S. planes for landing in low-visibility conditions. Now, airline CEOs sound more upbeat about the issue, reports Ars Technica.
Late last week, the FAA cleared 13 more radio altimeters that can filter out 5G transmissions from the C-band spectrum that is licensed to wireless operators. The list, which will likely grow again soon, now includes some regional jets.
For now, airline CEOs seem to be satisfied, even though the FAA hasn’t said definitively that altimeters will continue working after the temporary 5G limits around airports are lifted. “It’s taken a while to get to the right spot, but I feel like we’re in the right spot,” American Airlines Doug Parker told CNN. “I don’t think you’re going to see any material disruption going forward because of this.”
“While I wish it happened earlier, the good news is we now have everyone engaged, the FAA and DoT at the highest levels, the… aircraft manufacturers, airlines, and the telecoms,” United Airlines CEO Scott Kirby said. “While we don’t have a final resolution quite yet, I’m confident we’ll get there.”
“The technical experts that are working on it tell us it’s really not that complicated once they all are able to share information and work on it,” Parker also said. “So they seem encouraged that we’ll be able to address this in a way that allows for full deployment of 5G, including near airports. I don’t expect until we get to the point that everyone is really comfortable that you’ll see anything turned on near airports, because no one wants to go through this again.”
These statements marked a sudden shift, coming just days after Parker and Kirby signed a letter claiming that 5G on C-band would cause “catastrophic disruption” to air travel, Inside Towers reported.
Recently, the FAA started a process to evaluate and approve altimeters after saying that 5G on C-band (3.7 to 3.98 GHz) would disrupt altimeters that use spectrum from 4.2 GHz to 4.4 GHz. The FCC created a 220 MHz guard band to protect airplane equipment; older or poorly built altimeters may be unable to filter out transmissions from other spectrum bands.
The FCC approved use of C-band for 5G in February 2020, and auctioned the spectrum to wireless carriers in February 2021. The FAA didn’t start evaluating altimeters until recently, after arguing that 5G deployment should be blocked after carriers started preparing their equipment and towers to use C-band.
Expert Input
Harold Feld, a long-time telecom attorney and senior VP of consumer-advocacy group Public Knowledge, told Ars the FAA should have started setting up the process to evaluate altimeters shortly after the FCC approved the use of the spectrum for 5G—at the latest, after the $81 billion spectrum auction went forward.
“They spent their time relitigating the whole thing,” Feld said. “It was rash and reckless for the FAA to proceed without any kind of plan B. Had not Secretary [of Transportation Pete] Buttigieg personally intervened and the White House personally intervened and forced the FAA to actually stand this process up, then they still wouldn’t have stood it up on their own.”
Nearly two years ago, the FCC said its research showed C-band was safe to use. It still imposed power limits in the 220 MHz guard band. C-band spectrum is also being used for 5G in about 40 other countries without reports of interference to altimeters.
The aviation industry says the 5G power levels are lower in those other countries.
But Is It Really Solved?
The issue could spring back to life later this year when AT&T and Verizon lift temporary 5G restrictions around airports. One of the FAA’s statements last week seems to indicate its altimeter approvals are good for only as long as those voluntary restrictions are in place. Asked if that’s the case, the FAA didn’t answer Ars directly, but said. “The buffers around airports reduce 5G signal strengths and allow aircraft to land safely in low visibility conditions. Prior to these buffers, the signal strength was too strong in certain areas for low visibility landings to safely occur.”
Feld was disappointed in the FAA’s response, saying “it looks very much like a non-answer, which unfortunately has been consistent with everything the FAA has done until now.”
AT&T has said: “We will notify the FAA before any towers are activated within the additional buffer zone announced [last] Tuesday. We are continuing to engage with the FAA, FCC, and other stakeholders—including providing details about our deployments—to help facilitate the FAA’s technical assessments and clearance of aviation equipment.”
By Leslie Stimson, Inside Towers Washington Bureau Chief
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