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Technical Disagreement Grounds 5G Rollout

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Technical Disagreement Grounds 5G Rollout

November 17, 2021

A disagreement between the Federal Aviation Administration (FAA) and Federal Communications Commission (FCC) on spectrum interference has hit a wall leaving plans to roll out a 5G frequency band in limbo.

Wireless carriers had originally planned to begin rollout of 5G services on December 5th, but agreed to a one month delay as the FAA and FCC work to address safety concerns. At issue is whether or not planned deployment of 5G services in the C-band might interfere with aeronautical radar altimeters (RAs) which are essential to safely takeoff and land.


On November 2nd, the FAA, which has reportedly been in discussions with the FCC over this concern, issued a Special Airworthiness Information Bulletin (SAIB) regarding 5G. The Bulletin “recommends that radio altimeter manufacturers, aircraft manufacturers, and operators voluntarily provide to federal authorities specific information related to altimeter design and functionality, specifics on deployment and usage of radio altimeters in aircraft, and that they test and assess their equipment in conjunction with federal authorities.” In short, the FAA has begun collecting the information necessary to verify this safety concern that the aviation industry has raised for years.

On one side, the FAA, the Radio Technical Commission for Aeronautics (RTCA), and other aviation groups have urged the FCC to further delay 5G deployment. A 2020 RTCA report cited by the SAIB claims to “reveal a major risk that 5G telecommunications systems in the 3.7–3.98 GHz band will cause harmful interference to radar altimeters on all types of civil aircraft.” The report further claims that “this risk is widespread and has the potential for broad impacts to aviation operations in the United States, including the possibility of catastrophic failures leading to multiple fatalities, in the absence of appropriate mitigations.”

On the other side, the CTIA, which represents the wireless communications industry, has heavily criticized the RTCA report, citing “fundamental defects” in the report and significant “evidence that RTCA’s assertions are not supported by sound science.” Most notably, the CTIA points out that over three dozen countries already operate 5G services in the C-band spectrum “without causing harmful interference to aviation equipment.” The CTIA and telecom industry assert that, if the RTCA’s claims of interference were correct, we would already have seen significant failures in other countries.

For their part, the FCC has been working on a framework for 5G since 2016, and licenses for the particular subset of the C-band spectrum in question (3.7-3.98 GHz) were auctioned off back in February.

The FCC has also been examining the specific issue of RA interference as far back as 2019 when it commissioned the Aerospace Vehicle Systems Institute (AVSI) ⎼ a preeminent research cooperative at Texas A&M University backed by practically all major aviation companies including Airbus and Boeing ⎼ to produce a report on 5G interference with radio altimeters. The final report, which was released in early 2020, examined “the majority of RAs currently in use” and found that they “demonstrate some resilience to [out-of-band interference].” The AVSI report continues on to state that “this does not guarantee absolute protection,” and encouraged regulators to develop “rules and operational characteristics for new allocations in this frequency band” to ensure safe operation.

In response to the AVSI report, the FCC decided to put in place several safeguards, including a 220 MHz “guard band” to separate aviation equipment from potential 5G interference. The RTCA, and the FAA by extension, now claim that these safeguards are insufficient.

As we saw during the COVID-19 pandemic, access to high-speed internet has increasingly become a necessity not only for businesses but also for the American people. While broadband internet connections are an essential piece of keeping Americans connected, we are increasingly turning to mobile smartphones that require strong wireless connectivity. Polling by Pew Research Center shows that 85 percent of Americans now own smartphones, up from only 35 percent a decade ago. Whether you wish to stream the latest video content or collaborate with coworkers on your mobile device, 5G promises to untether Americans from their traditional fixed wireless connections. In addition to the expected increases in efficiency and productivity as a result of faster connections, 5G will also grant Americans greater mobility.

Pausing deployment for a single month is far from a death knell for 5G. The greater worry is that this delay will extend far beyond the postponement agreed to by wireless carriers. Waiting for manufacturers to voluntarily report crucial information on altimeters could drag on well into the new year. What’s more, with the holiday season approaching, it is unclear whether the FAA and FCC can reach a resolution before the scheduled deployment of 5G in January.

Rapid Resolution

Airplanes will continue to fly, and wireless carriers intend to move forward with the rollout of 5G in January. Thus, the question becomes how to resolve this conflict in the most rapid and efficient way.

Towards this end, Congress could assert its fact finding role and bring both sides to the table publicly. A hearing that brought the FAA, FCC, and various industry groups together to mediate the discussion could be helpful in coming to a resolution. More importantly, such a hearing would require the relevant federal agencies to address the public and answer lawmakers’ questions on this issue. Such a public discussion would also allow for scientific experts to discuss the details of the FAA’s recent SAIB, further elucidating the validity of these warnings.

The most important area of inquiry for such a hearing would be the claim by the CTIA that other countries have safely operated 5G with fewer safety measures and no reported interference. Since it appears that the FAA has yet to directly answer this claim, lawmakers could take the opportunity to question the agency on this point. Doing so could tease out any distinctions between countries that operate 5G services safely and the current approach being taken by the FCC. If there are notable differences, it would be worthwhile to learn from the experiences of European countries in particular that have been operating these services for much longer than here in the US.

It might also be useful to have the National Telecommunications and Information Administration (NTIA) take part in the hearing. Though less heavily involved than the FAA and FCC, the NTIA has already weighed in this debate in a limited way. In December 2020, when the FAA and Department of Transportation reportedly sent a letter to the NTIA requesting that they urge the FCC to delay the spectrum auction that included the 3.7-3.98 GHz band, NTIA refused to do so. According to the Wall Street Journal, then-acting NTIA head Adam Candeub stated that “career NTIA engineers concluded that FAA’s data failed to demonstrate a serious threat, and the determination was made to move forward with the auctions after consultation with Commerce officials at the highest level and White House staff.”

Given the NTIA’s role as the principal executive advisor on all things telecom, it would make sense to include them in any congressional inquiry. Since very little of NTIA’s analysis of 5G interference with RAs has been made public, Congress could use its fact finding capabilities to examine why the NTIA refused to advise the FCC to delay the spectrum auction. It might be incredibly enlightening to learn what NTIA engineers uncovered in their analysis of this issue.

With regard to the FCC, Congress could probe whether or not there are reasonable technical solutions that might mitigate the risk of interference. Among other things, Congress could clear up the debate around the guard band, clarifying whether 220 MHz is a sufficient safeguard to prevent interference.

With Congress approaching the holiday recess, the most apparent issue with seeking a hearing is time. This is especially true given that both the House and Senate are still engrossed in debate around the budget for FY 2022 with the current continuing resolution set to expire on December 3rd. Presuming that wireless carriers intend to move forward with deployment on January 5th, lawmakers would need to hold a hearing before heading home for the holidays.

Federal lawmakers and regulators should do everything they can to broker a resolution on this issue as soon as possible. While it is essential that we ensure planes can operate safely without RA interference, it is also important that the United States not needlessly delay the deployment of 5G. Reports have shown the massive economic potential of this technology, and the United States is already lagging in deployment of 5G. Hopefully, the FAA and FCC can reach a conclusion to their disagreement before January 5th.

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