The world is eagerly embracing 5G technology, the fifth generation wireless network that gives communications service providers the ability to deliver ultra-fast “intelligent connectivity.” Offering greater bandwidth and low latency, 5G can transfer huge amounts of data potentially 100 times faster than 4G, allow applications to connect and share data in real time, and enable networks to handle 100 times the number of connected devices.

More than a data network upgrade, 5G is widely described as the essential platform of the fourth industrial revolution (4IR), or Industry 4.0, which heralds the digitization of manufacturing and represents a major change in how the world is connected. This significant transformation is disrupting industries worldwide with emerging and evolving technologies like the Internet of Things (IoT), augmented reality and artificial intelligence.

5G’s high throughput and quality of service is already enabling rapid advancements in telemedicine, autonomous vehicles, collaborative robotics, and smart traffic control, which depend on data and machine learning in order to function effectively. With 5G, the average consumer’s experience is also enhanced by high-quality connectivity that enables working remotely, faster content streaming, and access to greater services.

Aviation itself is one of the industries that has most to gain from the advanced connectivity delivered by 5G. “Ever since 2G has been available, cellular data connectivity has been used to harvest aircraft operational data in bulk, which is automatically and routinely analyzed to improve flight safety,” said Willie Cecil, director, aircraft data and edge solutions for FLYHT Aerospace Solutions Ltd.

“Now there is increasing demand for ever-increasing amounts of data to feed maturing predictive maintenance, operational efficiency, and business intelligence applications enabled by artificial intelligence and machine learning technology. In the past, 3G and 4G technology have fallen short in their efforts to harvest the higher data volume available from new aircraft, but 5G provides the data rates and capacity that is needed,” said Cecil.

The United States’ deployment of 5G C-band services has not been smooth, but the FAA and other aviation stakeholders are working with wireless carriers to keep the focus on flight safety.
The United States’ deployment of 5G C-band services has not been smooth, but the FAA and other aviation stakeholders are working with wireless carriers to keep the focus on flight safety.

With so much at stake and so much to gain from 5G, countries around the globe have been eager to roll out 5G networks to gain a competitive advantage and “win the race to 5G.” To date, many countries, including Brazil, Canada, France, Japan, and Thailand, have successfully deployed their 5G networks without issue, while also including mitigations to preserve aviation safety and uninterrupted services — but by comparison, the U.S. rollout has been rockier.

microwave spectrum

During its annual general meeting in June, the International Air Transport Association (IATA) used the U.S. 5G experience as a cautionary tale. IATA Director General Willie Walsh urged governments to work closely with the aviation industry to ensure that aviation and incumbent aviation safety systems can safely co-exist with new 5G services. “We must not repeat the recent experience in the United States, where the rollout of C-band spectrum 5G services created enormous disruption to aviation, owing to the potential risk of interference with radio altimeters that are critical to aircraft landing and safety systems,” said Walsh.

The U.S. 5G Rollout

In the United States, 5G has already been widely deployed, including at airports in low-band frequencies previously used by earlier-generation networks, giving long range with data rates a little faster than 4G LTE; at mid-band frequencies providing much higher data rates; and at high-band “mm Wave” 5G frequencies, which are short range but provide ultra-fast data rates.

The first 5G mobile networks in the U.S. began rolling out in early 2019, when Verizon was the first telecommunications carrier to offer commercial 5G service in designated areas near Chicago and Minneapolis before expanding to other major cities. T-Mobile and AT&T soon followed suit with their own 5G networks. Later, T-Mobile was the first of the three carriers to establish the widest mid-band 5G coverage in the U.S. nationwide, including at airports, using sub-6 GHz frequencies that don’t conflict with aircraft radio altimeter frequencies.

This map, interactive on the website, shows the percentage of the U.S. commercial fleet and aircraft types that can land at U.S. airports with low-visibility approaches or a high-volume of aircraft with systems that could be adversely affected by 5G. FAA image.
This map, interactive on the website, shows the percentage of the U.S. commercial fleet and aircraft types that can land at U.S. airports with low-visibility approaches or a high-volume of aircraft with systems that could be adversely affected by 5G. FAA image.

The 5G rollout in the U.S. proceeded largely without incident until 2020, when — despite safety concerns voiced by the aviation sector — the U.S. Federal Communications Commission (FCC) auctioned off rights to a higher bandwidth range from 3.7 to 3.98 GHz, known as the C-band radio spectrum, frequencies adjacent to those used by radio altimeters.

It’s well documented that the FAA and other aviation stakeholders, including manufacturers and trade associations, had been consistently warning the FCC for many years about the potential for 5G C-band interference with radio altimeters. For example, A4A filed comments in 2018 raising those concerns in response to an FCC public notice about the potential use of C-band frequencies. Nevertheless, the FCC sold the C-band spectrum rights to telecommunications carriers for about $80 billion, and leading carriers Verizon and AT&T began building infrastructure to support their plans for 5G C-band services.

In late 2021, the FAA raised the alarm about the risk of potential adverse effects on radio altimeters, and a multi-stakeholder group comprising aviation trade associations and manufacturers contacted the FCC with concerns about the potential for 5G C-band interference with aircraft radio altimeters.

In support of safety considerations for U.S. flight operations, Verizon and AT&T agreed with the FAA on Jan. 18, 2022, to deploy 5G C-band on Jan. 19, 2022, except around key airports, and also to continue working with the federal government on safe 5G deployment at those airport locations. These voluntary agreements averted widespread disruption to the National Airspace System, the traveling and shipping public, the global supply chain, and the U.S. economy.

Airlines for America (A4A) published a report estimating that if the FAA had not agreed to work with manufacturers and wireless carriers on mitigation efforts, but instead gone forward with implementing safety restrictions on the operation of all types of civil aircraft in response to anticipated 5G interference issues, those actions potentially would have been disruptive to the U.S. air transportation system in the following ways:

• Impacting 32 million passengers

• Delaying, diverting, or cancelling 345,000 airline flights and 5,400 cargo flights

• Costing airline passengers $1.59 billion per year in disruption costs in the form of lost time, productivity and wages

Both of the wireless carriers agreed to the temporary and voluntary power mitigations near airports to minimize flight disruptions in the United States until July 1, 2023 — an offer contingent on the aviation industry’s measurable progress in improving radio altimeter resilience in preparation for wireless operators to raise their network power to the 62 dBm level previously authorized by the FCC.

Implications for the International Community

Airlines based outside the U.S. have been concerned about how the U.S.’s approach to 5G C-band implementation might delay or otherwise hamper their operations to the U.S. as the July 2023 milestone approaches. “Foreign airlines operating in U.S. airspace will have the same obligation to comply with the upgrade/retrofit deadline as domestic carriers, and as such, will be in the same type of queues for the necessary tools and avionics maintenance resources as other carriers,” said Amit Malhotra, spokesperson for 5G and avionics testing provider VIAVI Solutions.

FAA image.
FAA image.

In mid-2022, a coalition of the eight international airline associations representing almost all of the more than 100 foreign airlines that serve the U.S. market submitted a letter to FAA Acting Administrator Billy Nolen expressing their strong concern regarding the decision by the FAA to require that specific large commercial aircraft be retrofitted with new or modified radio altimeters by July 2023 in order to continue to utilize Category 2 and 3 low visibility procedures when landing at most major U.S. airports.

“As presented to the industry, this mandate will have a negative impact on the ability of major foreign carriers to maintain normal operations to the United States, as well as potentially impact other global operations, where U.S. airports are selected as destination alternates,” stated the coalition, made up of the African Airlines Association, Airlines for Europe, Arab Air Carriers’ Organization, Association of Asia Pacific Airlines, Association of South Pacific Airlines, Latin American and Caribbean Air Transport Association, International Air Transport Association, and National Airlines Council of Canada.

The coalition listed many concerns questioning the viability of a July 2023 deadline, including:

• The lack of any formal regulatory process from the FAA requiring air carriers to retrofit by July 2023

• Supply chain issues that might affect the ability of radio altimeter manufacturers to deliver enough retrofit kits to airlines in a timely way

• How the FAA will certify any retrofit solutions being offered by radio altimeter manufacturers

• The lack of FAA formal guidance or regulatory guidance on performance specifications for current and/or future radio altimeters with regards to 5G interference

• The potential exclusion of foreign carriers from U.S. markets due to an inability to meet the retrofit deadline, which raises potential issues under relevant U.S. bilateral air service agreements

As of this writing, IATA reports that the FAA has addressed at least some of the coalition’s stated concerns, but it still wants the FAA to do more. “Most recently, FAA has acknowledged that at most, 75% of all impacted aircraft will be retrofitted by the deadline. They are recommending that foreign airlines segment their fleets,” said Doug Lavin, IATA vice president of member and external relations, North America.

“We need a formal regulatory process with a mandate to underpin this entire exercise,” Lavin said. “This is particularly important for foreign airlines that are state-owned, because state-owned airlines’ governments will not necessarily permit their carriers to spend money on requirements from a foreign government (i.e., the U.S. government) without an accompanying formal mandate in the form of a rulemaking or some other regulatory action. We have done a survey of non-U.S. carriers, and it is become increasingly clear for the reasons outlined in the letter that it will be very difficult for a significant number of them to meet the deadline,” he concluded.

A Realistic Deadline?

During IATA’s annual meeting, Walsh expressed doubt in the U.S. timeline, noting that “FAA’s unilateral decision to require airlines to replace or upgrade their existing radio altimeters…by July 2023 is deeply disappointing and unrealistic.” However, other industry stakeholders have stated that the July 2023 deadline is reasonable and attainable.

“In general, the U.S. service providers are implementing C-band responsibly, as we have significant experience supporting them in meticulously testing networks before and during deployment,” said VIAVI’s Malhotra. “The general public has seen substantial benefits from this implementation, including wider coverage and faster and more reliable connectivity. Ultimately, the government’s upgrade/retrofit deadline will be met if industry can furnish the tools and the aviation industry can affordably schedule their deployment by July 2023.”

In Nolen’s response to the IATA-led coalition of airline associations, he wrote: “The FAA firmly believes that the most effective way for airlines to stay abreast of this situation is to work directly with aircraft manufacturers and suppliers through their existing relationships. The manufacturers are best positioned to assist their customers in determining how to meet the goal of ensuring specific fleets can continue to operate safely in U.S. airspace beyond July 1, 2023.”

For example, avionics manufacturer Thales has introduced an innovative band-pass filter design solution for its radio altimeters, which provides immunity to 5G signal interferences that otherwise impact safe aviation operations. “These upgraded radio altimeters have already begun to be deployed in airlines’ fleets operating in the USA, on track to complete all impacted Thales customers by or before the deadlines set forth by the FAA and 5G stakeholders,” according to the company.

“We understand that significant effort will be required to complete this work on the domestic and international fleets,” said Nolen in his letter. “Encouragingly, an increasing number of operators have placed orders for retrofit kits to protect their aircraft before the expiration of the mitigations. The FAA remains in close contact with OEMs and radio altimeter manufacturers to quickly identify and address any obstacles that might hinder this progress.”

Filters and replacement units for the mainline commercial fleet should be available on a schedule that would permit the radio altimeter retrofit work to be largely completed by July 2023, according to the FAA. The altimeter retrofits are designed to protect aircraft in the signal environment that the FCC has authorized for all licensees around major metropolitan areas.

The agency notes that Verizon and AT&T agreed to extend their voluntary mitigations to July 2023, even though they are legally able to turn on their systems at full FCC-approved power today, if they wanted to. However, 19 other companies licensed by the FCC are also prepared to activate their 5G networks by the end of 2023, and none of them are covered by this same voluntary agreement.

Airlines for America (A4A) graphic.
Airlines for America (A4A) graphic.

“Because the FAA has no authority to prevent or otherwise limit any wireless provider from operating in accordance with the FCC’s 2020 Rule and Order [expanding flexible use of the C-band for 5G], the aviation industry must rise to the challenge of completing the retrofits as soon as possible,” said Nolen.

Radio altimeter manufacturers have worked at an “unprecedented pace” with Embraer, Boeing, Airbus, and Mitsubishi Heavy Industries to develop and test filters and installation kits for these aircraft, according to the FAA. Customers began receiving the first kits in the summer, and in most cases, the kits can be installed in a few hours at airline maintenance facilities.

With respect to retrofit approvals, the National Civil Aviation Agency of Brazil has approved the retrofits to Embraer aircraft, and the European Union Aviation Safety Agency recently approved a specific radio altimeter retrofit on some Airbus models. The FAA has approved both retrofits and also is tracking the progress of additional approvals in the coming months.

Looking ahead, the FAA has reconvened the Safety Review Board to assess risk once the wireless providers raise power levels, which will inform any actions the agency must take to ensure continued safety in U.S. airspace. Nolen anticipates the agency will make the results of that evaluation public in the last quarter of 2022.

Why U.S. 5G Deployment Differed

Prior to their voluntary agreement with the FAA in January 2022, U.S. telecom providers Verizon and AT&T had been poised to activate new 5G services at higher power levels and on more critical radio frequencies than anywhere in the world without the necessary safety mitigations near airports. Many have asked, how did the U.S. land in this situation when all other countries so far have not?

According to Airlines for Aviation, comparisons of international examples versus U.S. 5G deployment are apples-to-oranges. Unlike the disconnect experienced by the FCC and FAA in the U.S., governments in other countries heeded aviation industry concerns and addressed them through mitigations in advance of their 5G rollouts.

A4A also reported that the allocated frequencies for 5G internationally are generally farther away from the radio frequency band used by radio altimeters. In addition, the permitted power levels are often significantly lower than those authorized in the U.S. Many other countries have also effectively utilized a combination of exclusion zones around airports, lower power levels and directional changes to antennas to mitigate interference.

The FAA likewise noted that deployments of 5G technology in other countries often involve different conditions than those proposed for the U.S., including:

• Lower power levels

• Antennas adjusted to reduce potential interference to flights

• Different placement of antennas relative to airfields

• Frequencies with a different proximity to frequencies used by aviation equipment

Ultimately, though the path hasn’t always been smooth, the FAA says it continues to hold itself and the aviation sector to the highest safety standards while addressing its unique 5G deployment challenges.

For more information about 5G and aviation safety in the U.S., visit the FAA website at