The rollout of 5G in the United States has caused concerns in the aviation world for a few years now. Since the end of the last year, 5G has been a topic of regular discussion and there have been numerous updates to the 5G / Aviation saga. Let's see what is going on with 5G in the aviation industry.

5G continues to raise concerns

In December 2020, the FCC (Federal Communications Commission) hosted an auction for C-band frequencies that it was purchasing from satellite providers in the United States. At the time, industry aviation experts began to raise concerns saying that redeployed spectrum could pose a risk to aircraft coming in to land.

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Some industry groups argue the proposed auction of bandwidth presents a safety risk to aircraft. Photo: Miami Dade Aviation Department

At the time, the FCC along with the CTIA (a trade association that represents the wireless communications industry) argued that the new technology would not be an issue and risk passenger safety. A report from the Radio Technical Commission for Aeronautics (RTCA) titled "The Assessment of C-Band Mobile Telecommunications Interference Impact Low Range Radar Altimeter Operations" concluded,

"The results presented in this report reveal a major risk that 5G telecommunications systems in the 3.7–3.98 GHz band will cause harmful interference to radar altimeters on all types of civil aircraft...

The results of the study performed clearly indicate that this risk is widespread and has the potential for broad impacts to aviation operations in the United States, including the possibility of catastrophic failures leading to multiple fatalities, in the absence of appropriate mitigations."

5G was set to roll out in December of last year. The technology was going to roll out on the C-band spectrum, using frequencies just a couple of hundred megahertz below the protected aeronautical spectrum. Both IATA and the FAA raised the same concerns raised by industry experts in December 2020, that 5G equipment could interfere with sensitive aircraft equipment such as the radio altimeter. The FAA even issued a Special Airworthiness Bulletin on the issue.

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The radio altimeter measures the aircraft's altitude above the terrain by bouncing beams of radio waves to the ground and back and measuring how long the return takes. Photo: Getty Images

Countries all over the world had already begun rolling out the new cellular technology, and the United States was the only country that was raising concerns. The reason concerns were raised in the US was that the 5G spectrum would run from 3.7-3.98GHz, dangerously close to the global aeronautical band of 4.2-4.4GHz.

New airworthiness directives

The FAA released a pair of airworthiness directives in December 2021, recommending revisions to aircraft operating manuals. The FAA stated,

"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."

Specifically, the directives may have meant that only certain operations would be restricted when aircraft would have to use automatic and guided landing systems. A perfect example of a situation where an aircraft would use automatic and guided landing systems is low visibility. The FAA added,

"The FAA believes the expansion of 5G and aviation will safely co-exist. (...) The FAA is working closely with the Federal Communications Commission and wireless companies, and has made progress toward safely implementing the 5G expansion."

Gogo tower US authorities request a delay in 5G rollout

On December 31 of last year, Federal Aviation Administration Administrator Steve Dickson and United States Transportation Secretary Pete Buttigieg asked wireless providers to postpone the rollout of 5G which had already been delayed to January 5. In addition, the Airlines for America trade association also raised concerns about the new cellular technology.

FAA and US Department of Transportation (DOT) leadership asked for the delay, not meant to last more than two weeks,

"We ask that your companies continue to pause introducing commercial C-Band service for an additional short period of no more than two weeks beyond the currently scheduled deployment date of January 5."

Cell providers rejected the FAA's request

AT&T and Verizon, two of the US' largest cellular providers rejected the FAA's request to delay the rollout of 5G. Although the cellular providers rejected the request to delay the rollout, the companies agreed to maintain safety buffering C-band exclusion zones around airports for six months, a system that was already in place in France. The FAA issued a response to the communication, stating,

"We are reviewing the latest letter from the wireless companies on how to mitigate interference from 5G C-band transmissions. U.S. aviation safety standards will guide our next actions.”

5G rollout delayed by two weeks

Although initially rejecting the two-week delay, cellular companies ended up agreeing to the delay after the Air Line Pilots Association (ALPA) and Association of Flight Attendants-CWA (AFA) applied some pressure. In response to the cellular companies agreeing to the delay, the FAA said,

Safety is the core of our mission and this guides all of our decisions. The FAA thanks AT&T and Verizon for agreeing to a voluntary delay and for their proposed mitigations. We look forward to using the additional time and space to reduce flight disruptions associated with this 5G deployment."

Shortly after the cellular companies agreed to the delay, the FAA shared a list of airports that would have buffer zones when the 5G bands were switched on. Even with the buffer, the FAA warned that the deployment of the new technology would increase the risk of disruption during low visibility.

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Verizon is most impacted by the decision not to run on 5G antennas located close to airports. Photo: Verizon

Ongoing 5G drama attracts the attention of US Congress

In February, the administrator of the FAA, Stephen Dickson, testified before a Congress Subcommittee hearing in Washington DC. In the hearing, he had to explain why the agency was not prepared for the rollout of the new technology. Dickson stated that the first priority of the FAA was the safety of the United States airspace.

"We are confident we will work through this issue safely with minimal disruptions, but we acknowledge that some altimeters—especially older models used by certain segments of the aviation industry—may not receive approval as being safe in the presence of 5G emissions and interference, and may need to be replaced." - Stephen Dickson

Boeing 737s

In late February, the FAA released another airworthiness directive warning airlines that operated the Boeing 737 that interference from the 5G frequencies could affect radio altimeters. The directive applied to all Boeing 737 except the 200 and 200-c variants.

"This AD was prompted by a determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G C-Band), and a recent determination that, during approach, landings, and go-arounds, as a result of this interference, certain airplane systems may not properly function, resulting in increased flight crew workload while on approach with the flight director, auto-throttle, or autopilot engaged, which could result in reduced ability of the flight crew to maintain safe flight and landing of the airplane. This AD requires revising the limitations and operating procedures sections of the existing airplane flight manual (AFM) to incorporate specific operating procedures for instrument landing system (ILS) approaches, speed brake deployment, go-arounds, and missed approaches, when in the presence of 5G C-Band interference as identified by Notices to Air Missions (NOTAMs). The FAA is issuing this AD to address the unsafe condition on these products." - FAA

It is important to note that this was not a flight ban from the FAA, but rather, a warning.

FAA wants 5G sensitive aircraft equipment replaced

Last week, Simple Flying covered a story about the FAA wanting to remove 5G sensitive equipment from aircraft. The FAA is set to have a meeting to discuss how to ensure that 5G technology will not interfere with aircraft equipment after the six-month buffer ends on July 5. An FAA spokesperson told Simple Flying,

"The FAA hosted a roundtable discussion with about 40 aviation and wireless industry representatives on Wednesday to consider the next steps in the continued safe coexistence of aviation and 5G C-band wireless service. The groups had a wide-ranging and positive discussion and will continue to collaborate as they work to address the remaining technical challenges."

This is a roundup of the 5G aviation saga in the United States. As always, Simple Flying will continue to update our readers on the latest developments.