The U.S. Federal Aviation Administration has introduced new operating limits for aircraft flying into Canadian airspace if their radio altimeters have not been proven resistant to potential interference linked to 5G networks in the lower C-band. The measures take effect on July 1, 2026, the same day Canada removes part of the protective zones around airports that have so far reduced the risk of possible 5G signal interference with aircraft systems.

The radio altimeter is one of the key systems used during the final phases of flight, providing the aircraft with precise information about its height above the ground. This data is used by a range of automated and safety systems, especially during approach and landing, including autoland functions, advanced warning systems and certain operations in low-visibility conditions. According to the FAA, unreliable or incorrect radio altimeter data can increase crew workload and affect automation during critical phases of flight.

The new rules primarily apply to aircraft that have not yet been modified or certified as tolerant to 5G C-band interference. For such aircraft, operators must include new limitations in their flight documentation before continuing operations in Canada. These restrictions include a ban on certain CAT II and CAT III approaches, autoland operations, HUD landings to touchdown and some operations using enhanced flight vision systems.

For U.S. air carriers operating scheduled passenger or cargo services, the requirements are even more specific. Aircraft operating in Canadian airspace must have radio altimeters that meet FAA interference tolerance standards or must be equipped with appropriate filters. Aircraft already compliant with earlier FAA requirements related to 5G do not require additional modifications under the new directive.

The reason for the new measures lies in a change to Canada’s regulatory environment. In 2023, Canada introduced protective measures during the rollout of 5G networks in the 3.45–3.90 GHz frequency range. These included protection and exclusion zones around airports, signal direction limits near certain runways and nationwide restrictions on emissions toward aircraft. Transport Canada informed the FAA that part of these measures would change from July 1, 2026, creating a more demanding electromagnetic environment for aircraft without the necessary protection.

The FAA estimates that the broad directive could affect around 1,000 U.S.-registered aircraft, although the agency says it does not have a final figure for how many have already received the required upgrades or external filters. The directive applies to a wide range of transport and regional aircraft equipped with radio altimeters, including aircraft manufactured by Airbus, Boeing, Embraer, Bombardier, ATR, De Havilland Canada and Gulfstream.

Separate directives have also been issued for several Boeing types, including the 737 Classic and Next Generation families, older 747 variants, the 747-8, 777 and 787. In the case of the Boeing 787, the FAA specifically highlights the risk that unreliable radio altimeter data after landing could affect the aircraft’s ability to correctly detect the transition from air mode to ground mode. This could have consequences for thrust reverser activation, speedbrake deployment and engine idle behavior, potentially increasing the required landing distance in certain circumstances.

For passengers, the measure does not currently mean a general ban on flights to Canada or automatic route cancellations. Its impact will depend on the specific aircraft and its configuration. Modernized and compliant fleets will be able to continue operating without additional restrictions, while non-compliant aircraft will mainly face limitations during operations that depend on precise radio altimeter data, particularly in more demanding weather conditions.

Although the issue of interference between 5G networks and aircraft radio altimeters has gradually been addressed in recent years through equipment upgrades and regulatory adjustments, the FAA’s latest move shows that the matter is not yet fully closed. Rather than being a one-off issue linked only to the introduction of 5G networks in the United States, the topic is now resurfacing in Canada, where changes to airport protection measures require airlines to clearly confirm the technical compliance of their aircraft.