Verizon and AT&T agreed on January 3 to delay for two additional weeks activation of new 5G C-band wireless transmitters, after initially rejecting calls to do just that from aviation stakeholders and federal regulators concerned about potential interference with critical aviation safety equipment.
The long-simmering dispute between aviation stakeholders and the wireless industry over the potential for 5G C-band transmitters to render radio altimeters (also known as "radar altimeters") unreliable had been on course to significantly disrupt air travel, including airline flights and emergency medical transportation, on January 5. Verizon, AT&T, and the Federal Communications Commission that regulates them had each rebuffed requests to extend a pause in 5G C-band activation—but with pressure mounting, the two companies announced late on January 3 that they would voluntarily hold off on activation of the new transmitters until January 19.
Pilots, airlines, and other operators, including emergency medical transport providers, had grown increasingly concerned that time had run out to effectively plan for the activation of C-band transmitters that could interfere with critical avionics operating on nearby frequencies. The FAA issued airworthiness directives in December setting the stage for notices to air missions (notams) that would impose restrictions on a range of flight operations in poor weather.
Verizon and AT&T paid billions of dollars to license the C-band frequencies during an auction held in 2021. The companies, and the FCC, have long disputed the safety concerns voiced by aviation stakeholders, while operators, avionics manufacturers, and organizations including AOPA have warned that operations could be impacted at scores of airports, and beyond. Emergency medical helicopter operations away from airports could also be halted in poor weather.
Airlines have been coping in recent weeks with significant disruptions caused by winter weather and COVID-19 infections that reduced crew availability and led to thousands of flight cancellations and delays through the holiday travel season.
The voluntary delay was announced on the same day a coalition of aviation industry stakeholders—including AOPA—called on the White House to intervene on January 3:
“We are just hours away from this C-band 5G rollout, yet the aviation industry is still anxiously awaiting details on how aviation will be impacted and on how crew members will need to operate to maintain safety and minimize disruptions," said AOPA and nine other organizations, including the National Business Aviation Association and Helicopter Association International.
The aviation coalition has cited preliminary tests conducted by RTCA, a nonprofit association that develops consensus policies for aviation modernization, as a basis for concern that 5G C-band transmissions are likely to interfere with the only instrument on any aircraft that directly measures height above the ground or obstacles.
The coalition welcomed a voluntary decision announced in November by Verizon and AT&T to delay activation until January 5, but noted then that more time would likely be needed to fully understand the potential impact on the safety of aircraft operating in bad weather with radar altimeters.
Verizon and AT&T on January 2 rejected a request for further delay of new C-band transmitter activations made by U.S. Transportation Secretary Pete Buttigieg and FAA Administrator Steve Dickson. The CEOs of the two telecommunications giants offered temporary mitigations that were deemed inadequate on initial assessment by technical experts working for firms that make radar altimeters. For example, the two companies offered to voluntarily, for six months, "adopt the same C-Band radio exclusion zones that are already in use in France, with slight adaptation to reflect the modest technical differences in how C-band is being deployed in the two countries," AT&T CEO John Stankey and Verizon Communications Inc. CEO Hans Vestberg wrote in their January 2 response to Buttigieg and Dickson's request for delay. "The effect would be to further reduce C-band signal levels by at least 10 times on the runway or during the last mile of final approach and the first mile after takeoff."
Members of the aviation coalition, during a January 3 conference, said that the proposed mitigations do not represent the full extent of aviation-related 5G mitigations actually imposed in France, and aircraft-specific analysis would still be required to ensure that safety would not be compromised when flying in low visibility in the presence of 5G C-band signals.
If C-band activation proceeds this month, the FAA plans to issue notams that would limit operations at many airports in poor weather, compounding air travel delays and cancellations, and also complicating other operations including off-airport landings of emergency medical services helicopters, an issue that the mitigations proposed by the wireless industry do not address.
"We continue to work with our coalition partners to raise awareness of the safety concerns raised by experts as well as the economic impacts that disruption could impose," said AOPA Director of Airspace, Air Traffic, and Security Jim McClay. "We very much appreciate the FAA's diligence in working to protect the safety of the national airspace system. We hope that common sense will prevail so that interests on all sides are protected."