Acknowledging the desire by the Federal Aviation Administration (FAA) to continue analyzing the impact of C-band deployments on air safety, AT&T and Verizon agreed to a 6-month period whereby they’ll minimize power coming from C-band base stations.
Their pledge pertains to base stations both on a nationwide basis and to an even greater degree, around public airports and heliports.
The operators outlined their plan in a November 24 letter to Federal Communications Commission (FCC) Chairwoman Jessica Rosenworcel, first reported by The Wall Street Journal. The letter was submitted by Joan Marsh, EVP of federal regulatory relations at AT&T, and Kathleen Grillo, SVP, public policy and government affairs at Verizon.
“AT&T and Verizon are voluntarily adopting the precautionary measures described below despite the absence of any credible evidence that 5G deployments in the C-band will adversely affect radio altimeters in aircraft, as is confirmed by real-world experience around the globe,” they wrote.
Earlier this month, AT&T and Verizon agreed to delay their commercial C-band launches by a month, until January 5. That came after the FAA issued a warning over potential interference to airplane safety systems from upcoming 5G deployments in C-band frequencies.
Big C-band bucks
Verizon and AT&T were big spenders in the FCC’s C-band auction, which brought in a record $81 billion to U.S. coffers. Verizon spent about $45.5 billion, and AT&T spent about $23.4 billion for C-band licenses. Initial deployments in major U.S. markets were expected on December 5 – until the FAA sounded the alarm.
In their November 24 letter to Chairwoman Rocenworcel, AT&T and Verizon said they remain confident that 5G poses no risk to air safety. “5G systems have been deployed in the C-band in nearly 40 countries—with hundreds of thousands of operating base stations—without any reported incidents of harmful interference to radio altimeters and without the FAA expressing any concern regarding the safety of U.S.- registered aircraft operating in those locations,” they wrote.
However, they’re sensitive to the FAA’s concerns and are voluntarily adopting additional precautionary measures to supplement the protections already covered in the FCC’s rules. Since deferring the commercial launch by 30 days, AT&T and Verizon have met with FAA representatives on numerous occasions and “raced to provide the FAA with extraordinary access to their 5G network deployment designs, radiofrequency planning, and equipment performance,” the carriers wrote.
AT&T and Verizon also said they’re committed to continuing to work with the FAA and radio altimeter stakeholders in modeling and testing going forward.
Meanwhile, to alleviate any safety concerns, they worked with FCC staff and agreed on this set of measures that will last for six months – expiring July 6, 2022 – “unless credible evidence emerges that real-world interference would occur if the measures were relaxed.”
Those technical measures include limiting C-band effective isotropic radiated power (EIRP) on 5G base stations to no more than the lesser of: (a) 62 dBm/MHz or (b) 48 + 20 × log10(1/sin(Ɵ)) dBm/MHz, where Ɵ is the elevation angle above the horizontal plane of the base station antenna.
In addition, they’ll limit C-band EIRP for all 5G base stations to no more than 62 dBm/MHz, as well as impose a series of limits near public airports with paved runways.
Analysts assess economic impacts
In a Wednesday note for investors, analysts at New Street Research said from what they can tell, none of the commitments will have a long-term impact on the carriers’ 5G economic performance.
“That is, we don’t think the limitations will affect customers’ general perception of the service and therefore will not affect the value proposition that the customers will assign to the service. Further, given the evidence in the record to date, we don’t think the commitments will continue past July,” wrote New Street’s Blair Levin.
The outstanding question remains whether the FAA is now willing to signal that its concerns have been met, he said. “As we have written before, the FAA has problematic incentives in terms of resolving this dispute, but we think the letter, in conjunction with significant support, we believe, from the White House and the Hill, should move the FAA to declare victory and move on,” he added. “But it may be a week or more before we learn how the FAA views the contents of the letter.”
The fracas over C-band renewed concerns about ongoing problems between federal agencies about spectrum policies. The C-band dispute is the latest example of federal agencies second-guessing the FCC’s decisions on spectrum.