AT&T and Verizon agree to 5G power limits to resolve FAA safety concerns

AT&T and Verizon Communications are voluntarily agreeing to take further precautions to make sure cell towers transmitting 5G signals using newly acquired midband spectrum won't interfere with aircraft signals. The companies laid out their plan in a letter sent to the US Federal Communications Commission on Wednesday afternoon, in a move meant to defuse a conflict between the wireless and aviation industries. 

In the letter addressed to the FCC's acting chair, Jessica Rosenworcel, the companies said they plan to lower the power levels nationwide on their cell towers that'll transmit 5G signals over the so-called C-band of wireless spectrum. Additionally, they said they'd impose even stricter power limits on the use of this spectrum near regional airports and public helipads, according to the letter, which CNET reviewed. The companies proposed taking the action for a period of six months "while additional evidence from radio altimeter manufacturers is evaluated," AT&T said in a separate statement.  

"While we remain confident that 5G poses no risk to air safety, we are also sensitive to the Federal Aviation Administration's desire for additional analysis of this issue," the companies said in the letter. 

Earlier this month AT&T and Verizon agreed to temporarily pause rolling out 5G service on midband spectrum until Jan. 5. The move came in response to an FAA warning about potential interference between key cockpit safety devices and cell towers on the ground transmitting 5G signals. The FAA says towers on the ground transmitting 5G over the C-band of wireless spectrum could interfere with automated cockpit systems such as those that help planes land in poor weather. 

The Federal Communications Commission applauded the companies' efforts. 

"These technical mitigations represent one of the most comprehensive efforts in the world to safeguard aviation technologies," an agency spokesman said. "With these measures in place, the FCC will continue to work productively with the FAA so that 5G networks deploy both safely and swiftly." 

The dispute between the FAA and the wireless industry has called into question whether the 5G deployment plans of companies like AT&T and Verizon will be slowed. The wireless industry spent more than $80 billion on this wireless spectrum, which can transmit 5G signals further than ultra-high-frequency millimeter wave spectrum but still maintain faster download speeds of low frequency spectrum. But telecom specialists, such as Blair Levin, a former FCC official turned equities analyst, said Wednesday's developments make it more likely the issues will get resolved with little impact on carriers' 5G plans. 

"From what we can tell, none of these commitments will have a long-term impact on the economics of the carriers' 5G economic performance," he said in a research note to investors. "We believe that the carriers think these efforts are more than reasonable and therefore, they are planning on turning on the service, as currently planned on January 5. We think the letter increases the odds of that result."

The companies said in their letter that they'll continue to comply with the FCC's C-band rules that had been "carefully crafted to allow for C-band 5G use to safely co-exist with aviation." They added that they were taking the precautionary measures "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."

The telecom industry has argued since the FAA made public its concerns that there's no evidence of interference issues with respect to the C-band spectrum and flight equipment. CTIA, the wireless industry lobby group, said in a filing to the FCC earlier this month that "nearly 40 countries have already adopted rules and deployed hundreds of thousands of 5G base stations in the C-Band at similar frequencies and similar power levels -- and in some instances, at closer proximity to aviation operations -- than 5G will be in the U.S."

Still, the issue has caught the attention of members of Congress. Last week, Reps. Peter DeFazio, chair of the House Transportation and Infrastructure Committee, and Rick Larsen, chair of the Aviation Subcommittee, sent a letter to the FCC, accusing the agency of a "deploy now, fix later" strategy that "roll(s) the dice with safety." They have asked the FCC to provide more data to the FAA and have also asked the FCC to prohibit any 5G broadband transmissions on the C-band spectrum until the FAA has concluded a risk assessment.

But there are signals that a deal is being worked out. At her confirmation hearing in the Senate last week, Rosenworcel noted that discussions were ongoing in response to a question about the dispute, saying, "You asked if I have confidence in our ability to resolve these issues with mitigation. The answer to that is yes."

Levin also said in a research note earlier this week that the White House has been hosting meetings among the stakeholders, which he believes increases the likelihood that the two sides will come to an agreement. 

Former FCC Chair Tom Wheeler agrees that a solution is close at hand, he said in a blog post for the Brookings Institution on Monday. He said the Biden administration's involvement, in conjunction with the work done by the FCC's engineering office to examine the technical issues, should be enough to put the issue to rest. He added that the FCC has a history of effectively dealing with interference concerns of older applications when new swaths of spectrum are allocated for commercial use. 

"The physics involved in this situation are well known," Wheeler said. "The mitigation techniques are well known. The standard-setting process is well known. The importance of getting 5G up and running while protecting flyers is well known."

Wheeler continued, "The science here is pretty clear -- it is hard to repeal the laws of physics. The real politick of this comes down to the costs of fixing the altimeters, just like the wheelchairs, hearing aids, and pacemakers were fixed."