As this is a developing situation, ALPA will update this page with additional operational resources and information for pilots as they become available. Learn more about this issue.

In early 2021, the Federal Communications Commission (FCC) awarded the mobile wireless industry radio spectrum to operate 5G transmissions in the “C-Band,” or 3.7-3.98 GHz, adjacent to the spectrum used by radar altimeters. This approval was made despite the aviation industry informing the FCC since 2018 of the need to ensure that radar altimeters are protected from 5G interference. The 5G signals in the United States are at higher power levels than any other deployment currently in use elsewhere in the world and also with closer proximity to airports. 

In the United States, wireless broadband deployment was originally scheduled to begin on December 5, 2021. After high-level talks, mobile wireless has agreed with the Federal Aviation Administration  (FAA) to delay broadcast of C-Band 5G until January 19, 2022, and placed voluntary limitations to C-Band 5G deployment until July 5, 2022, to permit continued access to airport by a substantial portion of the airline fleet. On Friday June 17, 2022, FAA convened a meeting of key aviation stakeholders including ALPA to inform them of FAA’s strategy for future co-existence with C-Band 5G transmissions.  Mobile wireless industry has committed to continue current voluntary limits until January 2023, and relaxed limits until July 2023.  This will prevent significant disruption after July 5, 2022, when the original agreement was due to expire. In conjunction with mobile wireless’s extension, FAA has received commitments from operators of the lowest performing radar altimeters (Embraer regional jets and certain legacy aircraft equipped with particular models of radar altimeters) to upgrade them with Radio Frequency (RF) filters by January 2023.  FAA continues to work with both industries on resolving the significant outstanding issues for the remaining airline fleet for July 2023.    The goal of these upgrades is to eliminate the current Alternate Methods of Compliance (AMOCs) and their associated airport/runway lists that are cumbersome and difficult for airlines and pilots to manage, but it is too soon to tell whether this goal can be met for all aircraft by July 2023.

Canada has also approved 5G in the C-Band, but with restrictions against using C-Band in the vicinity of 26 airports and other measures to ensure aviation safety. Canada has convened a 5G Radar Altimeter Working Group within the Radio Advisory Board of Canada to work through what operational limitations would apply on both mobile wireless and aviation to ensure safety as Canada plans their 5G deployment.

Keep reading for guidance for both U.S. and Canadian airline operations.

Radar altimeter interference from 5G signals can take the form of loss of radar altitude information or, worse, incorrect radar altitude information unknowingly being generated. There have been fatal accidents associated with incorrect radar altitude, most recently Turkish Airlines Flight 1951 in Amsterdam in 2009.

Altitude information derived from radar altimeters has been deeply integrated into aircraft systems and automation, with the latest aircraft using it to change aircraft handling qualities and prepare systems such as ground spoilers and thrust reversers for deployment prior to touchdown. This is in addition to radio altimeter use for autoland and in Category (CAT) II/III and Required Navigation Performance (RNP) AR approaches.

When operating in U.S. airspace, the following operations requiring radio altimeter are prohibited in the presence of 5G C-Band wireless broadband interference as identified by NOTAM (NOTAMs will be issued to state the specific airports where the radio altimeter is unreliable due to the presence of 5G C-Band wireless broadband interference): 

It is further anticipated that, depending on the aircraft, aircraft manufactures may identify additional limitations on specific aircraft. If they do, the FAA may restrict the use of other aircraft systems with additional ADs. The limitations imposed by the ADs protect operations by preventing the most critical hazards from occurring in the case of radar altimeter interference. It is not yet clear how these ADs will change as July 2023 approaches.

The FAA has developed a process by which better performing radar altimeters that are able to reject 5G interference can be approved to operate without regard to the AD and NOTAMs. These AMOC approvals will be specific to a combination of aircraft model and radar altimeter model.

The method of approval will take into consideration the performance of the aircraft/radar altimeter combination, as well as the location and power of the 5G transmitter in the vicinity of the airport. Therefore, the AMOCs are being issued with a list of airports where they are effective.

It is critical for pilots to be aware of and comply with any restrictions imposed via AD, AFM, and NOTAMs by the FAA and airline. The flight manual restrictions from the airworthiness directive coupled with NOTAMs that inform of the presence of 5G (C-Band) or restrictions of specific instrument procedures are important triggers, that pilots must carefully evaluate their aircraft’s ability to be safely operated and determine what additional contingencies must be considered.

During flight planning and advanced preparation, consider whether the weather forecast allows for the use of the available instrument approach procedures, should an alternate airport be required. Alternate airports may need to be selected that are further away from the intended destination and may impact fuel loading plans significantly.

Follow company guidance for operating in the 5G interference areas and actively pursue information from your air carrier when you have questions.

Pilots are also advised to:

If a radar altimeter anomaly is seen in operations:

Canadian Aviation Regulation 605.84 already requires US-type-certificated aircraft registered in Canada to comply with US ADs when operating in the US.  Transport Canada has additionally issued Canadian Airworthiness Directive CF-2021-52 extending this requirement to all Canadian-registered aircraft that fly in the US, and Canadian members are therefore also prohibited from performing the operations listed above on this page when the appropriate NOTAMs are in effect.

Canada has also approved 5G in the C-Band but with restrictions against using C-Band in the vicinity of 26 airports and other measures to ensure aviation safety. Canada is not expected to start 5G service in the C-Band until June 2022 and will initially operate in a lower frequency band (3.45-3.65 GHz). Service in the same frequencies as the United States will start no earlier than 2023.

View an interactive map showing the location and extent of protected and exclusion zones around these airports.

Any additional restrictions on operations by Transport Canada will be added here as they become available.

In December 2021, the Radio Advisory Board of Canada (RABC) stood up a working group chaired by one representative each from aviation and mobile wireless to work through the technical issues on how C-Band 5G and aviation radar altimeters can coexist. The working group is overseen jointly by Transport Canada and Innovation, Science, and Economic Development (ISED) Canada. ISED is the radio spectrum regulator of Canada. ALPA is a member of this working group.

ISED and Transport Canada have worked together to perform laboratory and flight testing of radar altimeter equipment in the presence of C-Band 5G transmissions. As of June 21, 2022, ISED Canada and Transport Canada are performing analyses based on the lab and flight test data and will brief the aviation and mobile wireless working group in the near future.  It is not yet clear whether or how Canada will use information about the FAA’s plan for radar altimeter retrofits in their findings and rules going forward.

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