The Ongoing Dispute Over Mobile C-Band Deployments


If you were one of the many people trying to travel by plane over the past few weeks, you may have experienced a last-minute flight delay or cancellation due not to COVID-19, but a new culprit: a recent planned rollout of 5G wireless services.  You may also wonder why 5G and safety have been buzzwords that have reached the top of news headlines recently, even meriting a reference during President Biden’s press conference a few weeks ago.

Fears of “planes falling out of the sky” and “catastrophic” impacts to flights have been voiced over the past few months due to a dispute that involves a wide range of interested parties, including airlines, airplane manufacturers and wireless carriers, as well as federal agencies, such as the Federal Communications Commission (“FCC”), the Federal Aviation Administration (“FAA”) and the National Telecommunications and Information Administration (“NTIA”) – as well as The White House.  These concerns were raised regarding the potential impact on aviation communications of the imminent deployment of wireless service over a specific range of wireless spectrum frequencies known as the C-band.

The dispute’s origins lie in aviation industry claims that the 5G rollout in the C-band may dangerously interfere with altimeters – airplane equipment that helps airplanes gauge height above ground and safely land – and that accordingly wireless carriers should either not utilize the C-band around airports or take additional precautions to prevent interference that could adversely affect this equipment.  The wireless industry sits on the other side of the debate, rejecting the notion that there is significant potential for interference, and arguing that interference concerns were addressed during the FCC’s open proceeding on the C-band, years before wireless carriers spent billions of dollars on C-band spectrum licenses.

History of the C-band and 5G

The C-band traditionally has been used for satellite and broadcasting services.  In 2020, after a long (and often heated) debate, the FCC adopted rules that repurposed a portion of this spectrum (3.7-3.98 GHz) in the contiguous United States for flexible use services, including wireless communications.  The driving force behind this decision was a desire to increase the amount of spectrum available for 5G, the next generation of wireless communications technology that will permit substantially faster data transfer speeds and potentially enable new applications, such as virtual reality and others.  The FCC has lauded the potential for 5G to “revolutionize healthcare, transportation, agriculture, education, and many other facets of our economy and society,” and noted that the C-band frequencies have favorable propagation characteristics beneficial to supporting 5G services.

The FCC began examining whether C-band spectrum could be made available for 5G use in 2017, and after adopting the new rules, held a public auction for spectrum licenses at the end of 2020.  Mobile carriers spent over $81 billion for spectrum licensing rights to the C-band, with Verizon and AT&T spending the most and winning the highest number of licenses.

The Dispute

As the December 2021 deadline for launching wireless service over the lower portion of the C-band approached, the FAA responded to aviation industry concerns and raised questions about whether C-band wireless services would cause harmful interference to airline services that could lead to “catastrophic” results.  The central focus of this controversy is the claim that use of the C-band by mobile operators could interfere with altimeters essential for safely landing airplanes.  Altimeters operate in the nearby 4.2-4.4 GHz range, generating concern that 5G emissions will interfere with certain outdated equipment.

Though the FCC has acknowledged the importance of preventing interference with altimeters, it previously determined in the C-band proceeding that safeguards adopted therein were sufficient to protect these services.

The different opinions on the impact of the 5G rollout on air traffic have led to mixed messaging and consumer confusion.  The FAA threatened to cancel or reroute aircraft scheduled to land at airports near 5G C-band towers, requesting that mobile carriers delay the rollout of 5G in the C-band to prevent this disruption.  As a result, AT&T and Verizon have twice agreed to delay their nationwide launch of 5G in the C-band to provide the FAA with additional time to assess the issue.  AT&T and Verizon first agreed to a month’s delay, after the FAA threatened to issue regulations that could disrupt air traffic.  Then, a letter from Transportation Secretary Pete Buttigieg and FAA Administrator Steve Dickson on New Year’s Eve requested the companies further delay the rollout another two weeks.  Verizon and AT&T initially pushed back, but ultimately agreed.

On January 19, 2021, AT&T and Verizon finally launched a modified rollout of 5G on the C-band with 90 percent of the initially planned tower deployment.  The wireless carriers voluntarily agreed to postpone the other 10% of its rollout, comprised of towers near certain airports.  Despite this compromise, over 300 flights were still cancelled after the FAA announced that some airports would face restrictions to further protect potentially vulnerable aircraft.

It is unclear what the next steps will be as wireless carriers seek to expand 5G C-band coverage.  According to the FAA, 22 percent of the U.S. commercial fleet still does not have approval for “low-visibility landings” at airports where wireless carriers have deployed 5G in the C-band nearby.  The FAA continues to test and approve altimeters, and does not appear to have categorically rejected any, though it “anticipates” there will be some susceptible to interference.  Though the White House committed to reaching a permanent solution, there has been no announced deadline or any promise that such a solution would include deployment around the airports at issue.

Embedded in this controversy are issues of abiding importance — which federal agency holds ultimate authority when it comes to spectrum regulation and sharing, and how should issues between different governmental authorities be resolved.  Should the FCC, the expert agency when it comes to spectrum regulation, have the final say?  Or, should other agencies, such as the FAA, have some level of parallel authority with regard to spectrum issues affecting their areas of expertise?  As demonstrated above, supported, understandable rules of the road are needed to help prevent these types of issues from arising at the last minute, with all the attendant disruption, and to help ensure compatible promotion of multiple essential goals, such as 5G deployment and safe air travel.

UPDATED 1/28/2022 at 3:30 PM: The FAA announced that AT&T and Verizon have agreed on steps that will permit more aircraft to use airports while permitting more towers to deploy 5G service.  The announcement stated that the FAA is using more precise data provided by the carriers to determine how 5G C-band signals interact with aircraft equipment.

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