5G and Aviation Safety
The FAA, collaborating with the aviation sector and wireless providers, has completed work to ensure that radio signals from newly activated wireless telecommunications systems can coexist safely with flight operations in the United States until at least January 1, 2028. Voluntary mitigations by the telecommunication operators, combined with aircraft radio altimeter retrofits by aviation operators, have resulted in the fielding of 5G C-Band with minimized impacts acceptable to both industries.
Using this successful collaboration as a blueprint, the FAA and the Aerospace Industry Association (AIA) cohosted a government and industry roundtable on November 7, 2024 at FAA Headquarters in Washington, DC. The purpose of the roundtable was to initiate discussion between government and industry stakeholders in order to ensure continued safe aviation operations and the safe and efficient use of spectrum in the C-Band beyond January 1, 2028. The meeting minutes are available and subsequent progress updates will also be posted.
How the FAA Helped to Integrate 5G
On January 9, 2023, the Federal Aviation Administration proposed an Airworthiness Directive (AD) that would continue to allow aviation and 5G C-Band to safely coexist. The directive requires aircraft in the United States after Feb.1, 2024 to be equipped to safely operate in the vicinity of 5G C-Band wireless signals. The directive would mandate that transport category airplanes used in scheduled passenger or cargo flight operations have 5G C-Band-tolerant radio altimeters, or install an acceptable radio frequency filter.
The agency issued a deadline for airlines to upgrade airplane altimeters by July 1, 2023. The deadline went into effect just before new rules prohibiting certain landings in low-visibility conditions without upgraded altimeters.
This came after the FAA reached a voluntary agreement with Verizon and AT&T to delay some C-Band and 5G usage until July 1, 2023 to allow air carriers time to retrofit aircraft altimeters to ensure they will not face interference. As of the end of September 2023, the entire U.S. airline fleet has upgraded their equipment and the risk of 5G interference has been mitigated.
Collaboration with Wireless Companies
On January 3, 2022 the FAA came to an agreement with AT&T and Verizon, agreeing to a voluntary delay and mitigations which could substantially reduce disruptions to air operations.
On January 7, 2022 the FAA released a list of 50 airports that had buffer zones when wireless companies turned on 5G C-band service. Traffic volume, the number of low-visibility days and geographic location factored into the selection. The wireless companies agreed to turn off transmitters and make other adjustments near these airports for six months to minimize potential 5G interference with sensitive aircraft instruments used in low-visibility landings.
During the January 5-18, 2022 delay period, the FAA:
- Received vital 5G transmitter location and power level information from the wireless companies.
- Facilitated data sharing between avionics manufacturers and wireless companies.
- Worked with airlines to help manage and minimize potential delays and cancellations in affected areas.
- Determined that some GPS-guided approaches may be used at certain airports.
- Educated aviation stakeholders.
- Worked with airlines on how they can demonstrate altimeters are safe and reliable in certain 5G C-band environments. This is known as the Alternative Method of Compliance (AMOC) process.
5G Background
Safety is our mission, and it guides all of our decisions. In the United States, 5G services launched in 46 markets on January 19, 2022, using frequencies in a radio spectrum called the C-band. These frequencies can be close to those used by radio altimeters, an important piece of safety equipment in aircraft. To make sure that this does not lead to hazardous interference, the FAA required that radio altimeters are accurate and reliable.
5G and aviation have safely coexisted in other countries because power levels have been reduced around airports and the industries have worked together prior to deployment. For years, we have been working to find a solution in the United States. The risk of 5G interference to commercial passenger aircraft was successfully mitigated by the end of September 2023.
- Since 2015, the FAA and the world aviation industry jointly raised concerns both industries would need to address to achieve similar results and had ongoing technical discussions. In the World Radio Conference proposal, the proposal only supported an international mobile telecommunications (IMT—i.e., 5G) allocation in the 3.4 to 3.7 GHz spectrum—not the 3.7 to 3.98 GHz spectrum that is the issue for radio altimeters.
- In 2018, Boeing raised concerns and proposed a solution. Additionally, ICAO, the aviation arm of the United Nations, identified that any use of the bands near 4.2 to 4.4 GHz should be contingent upon Radio Altimeter Studies.
- In 2018, the Air Line Pilots Association raised concerns to the FCC.
- In 2020 ahead of the auction for 5G C-Band, the FAA again raised concerns and asked for a postponement to collaborate on a solution. The NTIA, the federal government coordinator on spectrum disputes, failed to put the 2020 letter into the FCC's docket.
- Throughout 2021, the aviation industry continued to ask for additional collaboration and time in anticipation of the complications we now face. The industry also held several meetings throughout the year to find solutions, including in June and October.
- Throughout 2022 and 2023, the FAA, in collaboration with the aerospace industry and wireless communications companies, held roundtables, issued rules and Airworthiness Directives, and educated aviation stakeholders on the changing rules and regulations surrounding 5G C-band deployment.
- July 1, 2023, new legislation goes into effect restricting airlines when performing landings in low-visibility conditions, due to the potential of 5G signals to interfere with planes' altimeters. Airlines are required to either upgrade their equipment or restrict the use of unequipped planes.
- September 2023, equipment upgrades completed on the U.S. airline fleet.
Radio altimeters provide highly accurate information about an aircraft’s height above the ground. Data from these radio altimeters informs other safety equipment on the plane, including navigation instruments, terrain awareness, and collision-avoidance systems.
Because the proposed 5G deployment involved a new combination of power levels, frequencies, proximity to flight operations, and other factors, the FAA imposed restrictions on flight operations using certain types of radio altimeter equipment close to antennas in 5G networks.
The FAA worked to determine which radar altimeters would be reliable and accurate with 5G C-Band deployed in the United States. After the agreement with the wireless companies was reached, the agency made progress to safely reduce the risk of delays and cancellations as wireless companies share more data and manufacturer altimeter testing results arrive.
In the time approaching the July 1 deadline, more than 85% of the domestic commercial airline fleet and about 66% of the international fleet were equipped with radio altimeters that could operate safely in the U.S. 5G C-band environment.
The FAA issued 7 Airworthiness Directives (AD) to provide framework and gather information to avoid potential effects on aviation safety equipment:
- January 9, 2023 – FAA issues proposed Airworthiness Directive that will only allow aircraft with retrofitted radio altimeters to operate in the United States after February 1, 2024
- February 23, 2022 – Boeing 737 Airworthiness Directive
- February 14, 2022 – Boeing 757/767 Airworthiness Directive
- January 27, 2022 – Boeing 737 MAX Airworthiness Directive
- January 25, 2022 – Boeing 747/777 Airworthiness Directive
- December 7, 2021 – FAA releases 2 Airworthiness Directives to provide framework and gather information on potential effects of aviation safety equipment.
The FAA held 8 5G roundtables in 2022 and 2023 which allowed us to collaborate with aviation and wireless industry representatives to address the technical changes that needed to happen.
- DOT and FAA letter to AT&T and Verizon
- SAFO 21007 - Safety Alert for Operators on Risk of Potential Adverse Effects on Radio Altimeters when Operating in the Presence of 5G C-Band Interference
- AD 2021-23-12 - Airworthiness Directive on altimeter interference and airplanes
- AD 2021-23-13 - Airworthiness Directive on altimeter interference and helicopters
- FCC Partial Economic Areas (PEAs) 1-4, 6-10, 12-19, 21-41, and 43-50
- DOT Letter to NTIA re: FCC3.7 GHz Band Auction