Representatives from the airline industry reported this week that their discussions with AT&T, Verizon and US government officials have reached a stalemate. As a result, they're asking the White House to step in and extend prohibitions on some flavors of 5G around airports.

And that could have far-reaching implications for a variety of companies, including T-Mobile and UScellular. So far those two companies have managed to remain out of the issue, in part because their C-band holdings won't become available until next year.

Importantly, the airline industry officials reported that the Federal Aviation Administration (FAA) has so far documented over 100 "incidents of potential 5G interference, the majority of which were found to have a direct RA [radar altimeter] impact resulting in safety alerts by systems such as the Terrain Avoidance Warning System."

Figure 1: (Source: frans lemmens/Alamy Stock Photo)

That's up from the roughly 80 incidents reported by IEEE Spectrum in October.

AT&T and Verizon started launching their 5G networks – using their new C-band spectrum holdings – in January 2022. However, that launch was marred by a noisy public relations debacle that involved worries by the airline industry that 5G operations in C-band spectrum could interfere with some aircraft radar altimeters. As a result, AT&T and Verizon have agreed to delay the launch of their C-band 5G networks around some airports – an important concession by the operators considering airports remain a hotbed of cellular traffic.

'It could have caused a crash'

The question of whether 5G interferes with aircraft radio altimeters has been a hot topic of discussion among spectrum experts for years. However, the IEEE Spectrum report sheds some real-world light on the issue.

For example, the publication reported that, in March 2022, a commercial jet landing on autopilot at Los Angeles International Airport suddenly began descending rapidly when it was just 100 feet above the ground. "I took control of the aircraft and raised the nose and landed," its pilot reported, according to IEEE Spectrum. "It was a very alarming pushover by the autopilot. In [other] conditions, it could have caused a crash."

The publication reported on dozens of other apparent cases of interference to aircraft altimeters, as reported by pilots themselves. IEEE Spectrum reported that the FAA declined to provide the full details of the reports, but that it appears to have received around 550 pilot reports between January and October, a much higher figure than in previous years. As of October, the FAA had reviewed over half of the reports, and was unable to rule out 5G interference in around 80 incidents.

Delays and compromises

Top officials from the US government, the US wireless industry and the global airline industry have held meetings on the topic since the beginning of November, according to Reuters. But in a new letter signed by a wide range of airline officials, "progress appears to be at a stalemate."

As a result, the airline officials are calling on the Biden administration to extend some deadlines beyond 2023 and to permanently change other guidelines, though the details were not included in the letter. At the heart of the issue is the airline industry's inability to quickly upgrade some altimeters so they won't be affected by 5G in C-band spectrum. The airline industry offered a variety of reasons for the delays, including a lack of regulatory guidance on some issues and some supply chain troubles that are delaying the necessary parts.

Officials from Verizon, AT&T and the CTIA – the US wireless industry's main trade association – did not respond to Light Reading requests for comment on the new letter.

The issue is pressing in part because "additional wireless providers that have not been part of these interim voluntary efforts" are planning to launch their own 5G services in C-band spectrum, according to the airline industry. The airline industry's letter didn't name any specific providers, but both T-Mobile and UScellular have hinted at their desire to launch 5G services in their own C-band spectrum holdings at some point in 2023.

A T-Mobile representative didn't immediately respond to requests for comment on the situation from Light Reading. "All Americans deserve to get connected as quickly as possible. It is time to get to work on their behalf — the operational challenges can be addressed, and any delay will be off the backs of Americans who need urgently to connect to the things that matter most. At UScellular, our mission is to connect the unconnected and we invested in C-Band spectrum to ensure that rural and regional areas have the highest-quality home and mobile broadband," Adriana Rios Welton, head of legal and government affairs at UScellular, said in a statement to Light Reading.

More and more moving parts

To be clear, the airline industry's C-band fight hasn't been the only contentious issue dogging that particular spectrum band.

For example, Intelsat and SES loudly battled with US regulators prior to the FCC's big C-band auction in 2021. That's because Intelsat, SES and some other satellite operators have been working to modify their existing systems in the C-band in order to free up roughly 300MHz for 5G operations.

After more than a year of debate, the FCC issued rules in 2020 designed to help pay the satellite operators the billions of dollars they would need to modify their systems in order to make way for 5G.

And so far, SES, Intelsat and others have reported relatively few hiccups in their work to free up C-band spectrum for 5G – aside from some complaints about sluggish and inconsistent US government reimbursements for their work.

Roughly a third of the C-band was released to 5G providers in 2021, and the remainder is scheduled to be freed up and released by 2023. That's the portion of the band owned by the likes of T-Mobile and UScellular.

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– Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano