FAA order to avoid interfering with 5G C-Band services; RootMetrics touts coverage vs performance advantages for 5G

The FCC’s C-Band spectrum (between 3.7 GHz and 4.2 GHz) auction earlier this year raised a staggering gross total of $81.17 billion [1.], smashing the previous auction record of $44 billion raised in the AWS-3 auction that ran in 2014-2015 and raised nearly $45 billion. The mid-band spectrum acquired by AT&T, Verizon, and T-Mobile, could mark a fundamental shift to the 5G landscape in the U.S.

Note 1. Verizon spent a jaw dropping $45B at the C-Band auction, AT&T invested about $23B, while T-Mobile spent $9B to augment its already substantial mid-band holdings.

However, there is a huge controversy over use of that band by wireless telcos.  The FAA and aviation industry groups say the new 5G service could interfere with radar or radio altimeters, gauges that measure the distance between aircraft and the ground. Information from those aviation devices feeds a number of cockpit safety systems used to land planes, avoid crashes and prevent midair collisions.

Today, the FAA warned that interference from planned use of 5G wireless spectrum posed an air safety risk and could result in flight diversions.

FAA outlined flight restrictions that will take effect on January 5, 2022 when new 5G C-Band services make their debut, even as regulators work with telecom and aerospace companies to avoid U.S. air traffic disruptions.  The FAA order would restrict pilots from operating automatic landing and other cockpit systems commonly used in poor weather, to avoid possible interference from 5G in the spectrum range known as the C-band.

The airports that would face potential disruptions will be identified in future notices, according to the FAA order, known as an airworthiness directive. Regulators and technical experts have been working to address concerns about potential safety risks to resolve a long-running dispute between the aviation and telecom industries.

“The FAA plans to use data provided by telecommunications providers to determine which airports within the United States have or will have C-band base stations or other devices that could potentially impact airplane systems,” the agency’s order said.

Data pertaining to 5G signals’ power levels and location are expected to help air-safety regulators limit disruptions, current and former government officials have said. Aviation industry groups have warned of potentially “debilitating impacts” from such flight restrictions, saying in a Nov. 18 letter to the FCC: “Air cargo and commercial air travel will likely cease at night and in any weather where the pilot cannot see the runway.”

  • The FAA said it was coordinating with the Federal Communications Commission and wireless companies and has made progress “toward safely implementing the 5G expansion.”
  • The FCC said it looks forward to further guidance from the FAA that takes into account a recently proposed solution from telecom companies.

The FAA said the new 5G service could interfere with gauges that measure the distance between aircraft and the ground.



AT&T and Verizon previously agreed to delay by a month their activation of the fifth-generation wireless service, which provides faster broadband speeds for a range of mobile devices. The 5G C-Band services had previously been due to go live Dec. 5, but the companies agreed to hold off because of the FAA’s aviation safety concerns.

On November 24th, AT&T and Verizon offered to limit the signal power of certain 5G base stations as an additional safeguard. On Monday, a representative from the Aerospace Industries Association told the FCC in a letter the carriers’ proposed limits were “inadequate and far too narrow” to address flight safety concerns.

The U.S. telecom industry has maintained that the new 5G service doesn’t pose a safety threat to aircraft, pointing to other countries’ experience with similar wireless services.

  • A Verizon spokesman said today that “there is no evidence that 5G operations using C-band spectrum pose any risk to aviation safety, as the real-world experience in dozens of countries already using this spectrum for 5G confirms.” The person added it was confident the FAA ultimately will conclude C-Band 5G use “poses no risk to air safety.”  Verizon says it’s on track to reach 100 million Americans with the new service in the first quarter of 2022 and was confident the FAA’s further analysis will find C-band service “poses no risk to air safety.”
  • An AT&T spokeswoman said today that the carrier recognizes the “paramount importance of air safety, and our use of the C-band spectrum will not undermine that imperative.”

In its order, the FAA said it determined that “no information has been presented that shows radio altimeters are not susceptible to interference” by the new 5G service. The FAA’s order said it affected an estimated 6,834 U.S.-registered airliners and other aircraft. A similar FAA order, also issued Tuesday, affects an estimated 1,828 helicopters.

The FAA also warned that interference from planned use of 5G wireless spectrum posed an air safety risk and could result in flight diversions.  Another FAA directive on Tuesday said the “unsafe condition” posed by the planned use required immediate action before the Jan. 5 deployment “because radio altimeter anomalies that are undetected by the aircraft automation or pilot, particularly close to the ground … could lead to loss of continued safe flight and landing.”

The FCC said it “continues to make progress working with the FAA and private entities to advance the safe and swift deployment of 5G networks … We look forward to updated guidance from the FAA in the coming weeks that reflects these developments.”


Dave Andersen of Rootmetrics believes that although it will likely take a year or two before C-Band spectrum gains widespread traction in the US, carriers are already planning (or using) new branding strategies to differentiate their various flavors of 5G. He states that mid-band spectrum in the 3.7 GHz to 3.98 GHz range should ultimately provide users with speeds much faster than those on existing LTE or nationwide low-band 5G networks, while offering an optimal blend of coverage plus performance that other types of spectrum can’t match.
The following table looks at how each carrier has dubbed its various 5G offerings, as well as the icons users can expect to see on smartphones when accessing different types of 5G. Note that T-Mobile plans to launch C-Band sometime in 2023.  Its current 5G mid-band service uses 2.5 GHz spectrum, rather than the 3.7 – 3.98 GHz of C-Band.  T-Mobile already covers 210 million people nationwide with Ultra Capacity 5G and 310 million with Extended Range 5G.
U.S. Carrier 5G branding and icons:
Carrier Low-band C-Band/mmWave Smartphone icon
AT&T Nationwide 5G 5G+ 5G+
T-Mobile Extended Range 5G Ultra Capacity 5G 5G UC
Verizon 5G Nationwide Ultra Wideband 5G 5G UW

As the table shows, the carriers’ branding strategies combine mid-band (including C-band) and mmWave into one moniker, which is a logical choice as both mid-band and mmWave 5G can deliver much faster speeds than the low-band 5G networks that carriers currently use to provide nationwide 5G service. In simple terms, when users see those icons on their phones, they should also see faster speeds.

Here’s a look at the three frequency bands being used for 5G services:

Andersen says, “mid-band spectrum can give users a level of 5G service that other types of spectrum can’t: a combination of broad coverage plus excellent speeds, rather than just one or the other, which is the case with low-band (broad coverage but slower speeds) or mmWave (super-fast speeds but small coverage areas).”

Looking ahead to when C-Band might become the dominant spectrum for 5G, Andersen wrote (emphasis added):

C-Band has always been a few years away from becoming the dominant flavor of 5G in the US, and its rollout has been delayed for a bit as the FAA analyzes any possible effects the spectrum could have on aviation. That said, the good news for AT&T and Verizon users is that both carriers will soon begin C-Band deployments, as they pledged to minimize power output from C-Band base stations, especially those close to airports.

The bottom line is that while C-Band will likely be available in some cities in early-to-mid 2022, before it can be rolled out on a broad scale, wireless carriers will need to add new towers, install new hardware and software, and update existing network infrastructure in cities across the country.

All of that takes time, so users likely won’t see a major boost in 5G performance from the C-Band auction for another year or two. But given the results we’ve already recorded on mid-band 5G in the US and other countries, the performance gains C-Band can offer could very well be worth the wait.

We’re looking forward to testing C-Band as rollouts begin and seeing its impact on the end-user 5G experience. In the meantime, keep checking back with RootMetrics for more 5G and mobile performance insights.

Airlines for America, an industry trade group representing major U.S. passenger and cargo carriers, said it would continue working with aviation and telecom regulators “to enable the rollout of 5G technology while also minimizing any disruption” to U.S. air traffic.

4 thoughts on “FAA order to avoid interfering with 5G C-Band services; RootMetrics touts coverage vs performance advantages for 5G

  1. Good update, Alan,

    I wonder if the resolution to this issue will include retrofitting and/or the replacement of radio altimeters? If so, one would think it would come from the windfall that the U.S. Treasury received from the C-Band auction. It will be interesting to see how it unfolds.

  2. US aviation groups are warning that the deployment of certain 5G mobile networks in the country could result in disruption to flights, including delays to air cargo shipments.

    The Aviation 5G Coalition, an industry consortium representing airlines, manufacturers and associations, said that AT&T and Verizon will activate their C-Band 5G on January 5.

    The group is not against the use of 5G but claimed that transmissions in the “C-Band” could interfere with radar altimeters when deployed close to airports.

    In response, the FAA has issued an order prohibiting many flight operations related to poor weather landings when C-Band 5G networks are within a certain range of airports.

    “Airlines operate safely in these conditions today but will be prohibited from operating in them if C-Band 5G is transmitted near the airport,” the group said.

    Potential impacts include delayed and cancelled passenger flights; delayed air cargo shipments; significant schedule disruptions; and inability for first responders, military, and law enforcement to fly helicopter missions.

    In a joint statement, the members of the Aviation 5G Coalition said: “Time is running out before millions of air travellers and the shipping public experience significant disruptions such as flight delays, flight cancellations and backups to the already-stressed supply chain.

    “We implore the Federal Communications Commission, Federal Aviation Association (FAA) and National Economic Council to continue meaningful discussions in good faith and to identify mitigations and reach a successful implementation plan that will ensure new 5G technologies can safely co-exist with the aviation industry.

    “We strongly believe that by working together these groups can create a win-win situation for all stakeholders – the telecommunications industry, the aviation industry and most importantly the millions of customers who depend on our services every day across the country.”

    The group has tabled its own set of counter proposals that it hopes will offset the concerns.

    HKSG Media Ltd.

  3. Dec 23, 2021 Update from Bloomberg:

    U.S. aviation regulators on Thursday expanded their warning about 5G service set to launch Jan. 5 on new frequencies, saying potential interference could have a broad impact on aircraft safety systems.

    The Federal Aviation Administration issued a Safety Alert for Operators warning that “a wide range” of aircraft safety devices could malfunction and laid out the process it will follow in coming days to potentially issue specific restrictions on flights.

    he FAA actions come as telecommunications and aviation companies agreed on Wednesday to share more data in an attempt to head off what has become a tense standoff over whether the 5G service could disrupt airlines and helicopter operations.

    “The FAA is working with the aviation and wireless industries to find a solution that allows 5G C-band and aviation to safely coexist,” the agency said in a statement that accompanied the release of the alert and a Special Airworthiness Information Bulletin.

    In the alert, the FAA identified 17 different safety systems and aircraft functions that could fail if 5G airwaves interfere with radar altimeters, which use radio waves to calculate an aircraft’s altitude.

    As talks with the telecommunications industry are underway, the FAA is preparing what are known as Notices to Air Missions that may restrict flights in dozens of locations, it said.

    The wireless industry and the Federal Communications Commission have said the new high-speed wireless service on the so-called C-band of spectrum don’t pose a threat, but the FAA and airlines are warning that there could be flight disruptions including delays and the diverting of planes to different airports. C-band airwaves are near the frequencies used by altimeters.

    “We share the FAA and FCC’s confidence that we can and will have safe flights and robust and reliable 5G,” Nick Ludlum, a spokesman for the CTIA telecommunications trade group, said in an email. “We continue to work closely with the aviation industry and we look forward to joining the nearly 40 countries already operating 5G in the C-band on January 5th.”

    A radar altimeter’s data is fed into numerous systems on aircraft, from basic help to pilots during landing to multiple safety devices, according to the FAA. Its data is used to prevent crashes into the ground and mid-air collisions, for example. But it also feeds aircraft automation that control throttle settings, takeoff guidance, windshear alerts and thrust reversers that help stop after landing.

    “Anomalous (missing or erroneous) radio altimeter inputs could cause these other systems to operate in an unexpected way during any phase of flight – most critically during takeoff, approach, and landing phases,” the FAA said in the safety alert.


  4. Another update: AT&T, Verizon Refuse FAA Request to Delay 5G Launch

    AT&T and Verizon rebuffed a request from federal transportation officials to voluntarily delay the launch of new 5G wireless services, extending a showdown that could lead to potentially disruptive U.S. flight restrictions as soon as this week.

    The cellphone carriers on Sunday offered a counterproposal that would further dim the power of their new 5G service for six months to match limits imposed by regulators in France, giving U.S. authorities more time to study more powerful signals’ effect on air traffic. The companies had planned to launch the service Wednesday in as many as 46 of the nation’s largest metropolitan areas.

    “If U.S. airlines are permitted to operate flights every day in France, then the same operating conditions should allow them to do so in the United States,” the chief executives wrote in a letter reviewed by The Wall Street Journal.

    The Federal Aviation Administration has been preparing to issue flight restrictions that could go into effect around the country as soon as Wednesday. The limits could restrict pilots from using certain automated systems to help land aircraft in bad weather, a move that could disrupt air travel and cargo shipments.

    “U.S. aviation safety standards will guide our next actions,” the FAA said Sunday. The agency declined to comment about when it might issue the flight limits in official notices to air missions.

    Telecom-industry officials have pointed to dozens of countries, including France, that have already allowed cellular service over parts or all of the frequencies in question, known as C-band. France is among the countries that have imposed wireless limits near airports while regulators study the effect the signals have on aircraft.

    The letter by AT&T CEO John Stankey and Verizon CEO Hans Vestberg was in response to one sent by Transportation Secretary Pete Buttigieg and Federal Aviation Administration chief Steve Dickson late Friday. The New Year’s Eve missive asked the carriers to postpone their planned 5G launch by “no more than two weeks” while officials worked to address the wireless services’ effect on specific airports over the coming weeks.

    Air-safety regulators have said the new cellular services could confuse key cockpit safety systems and have been preparing to impose potentially disruptive flight restrictions.

    AT&T and Verizon, which combined serve more than half of all U.S. cellphone connections, disputed officials’ claims of air-safety risks. The companies postponed a planned December debut of the new signals to provide more time for telecom and aviation regulators to share information about the wireless infrastructure and aircraft equipment in question.

    Wireless companies later pledged to limit C-band signals for another six months through early July. The letter Sunday proposed even stricter 5G limits over the same period.

    But the telecom CEOs said transportation regulators’ latest delay request would be to “the detriment of millions of our consumer, business and government customers.” The CEOs added that carriers spent more than $80 billion to acquire the licenses in a Federal Communications Commission auction that closed in January 2021.

    FCC authorities padded the spectrum they auctioned with a swath of buffer frequencies to prevent interference with cockpit systems. But air-safety regulators have expressed concern that more sensitive altimeters could mistake cellular transmissions for terrain.

    AT&T and Verizon have spent the past year preparing to turn on new signals to provide new fifth-generation wireless technology, a faster and more capable mobile service. Wireless companies in other countries already use similar frequencies, but the spectrum wasn’t available to U.S. providers until recently.

    Without a resolution to the dispute, Messrs. Buttigieg and Dickson warned the FAA’s flight limits would bring severe economic consequences.

    “Failure to reach a solution by Jan. 5 will force the U.S. aviation sector to take steps to protect the safety of the traveling public, particularly during periods of low visibility or inclement weather,” they wrote in their Dec. 31 letter.

    Airlines have been bracing for significant flight cancellations and diversions due to potential FAA flight restrictions because of the regulator’s aviation-safety concerns. Pilots and airlines had been awaiting details of potential FAA flight restrictions that limit the use of systems that rely on radar altimeters.

    Over the past week, U.S. air travel has been snarled by a mix of winter storms and staffing challenges because of increasing ranks of airline crews calling in sick with Covid-19 as the U.S. deals with a surge by the Omicron variant. Thousands of flights have been canceled and delayed.

    The competing proposals are the latest in a flurry of behind-the-scenes work by aerospace manufacturers and wireless companies, their regulators and senior White House officials. As they attempted to hammer out solutions to allow the new 5G service to go live without prompting severe flight restrictions, the trade group Airlines for America asked the FCC to consider an emergency request to delay the wireless rollout.

    The airline trade group said Sunday it continued to urge the FCC and telecom industry to work with the FAA and aviation industry to reach a compromise.

    The FCC is an independent agency that acts outside the Biden administration’s direct authority. The commission hasn’t shown an interest in limiting licenses that it found safe to grant in a 2020 order authorizing the 5G auction.

    An FCC spokeswoman declined to comment on the airline group’s request but said the commission remained optimistic that “by working together we can both advance the wireless economy and ensure aviation safety.”


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