The U.S. Federal Aviation Administration issued several airworthiness directives Friday for Boeing Co. jets, including 737 Max aircraft and 787 Dreamliners, operating in Canadian airspace that could face interference from 5G radio waves.

Radio altimeters used in thousands of Boeing aircraft could be disrupted by wireless broadband operations in a specific portion of the radio spectrum, known as the 5G lower C-band, that may result in certain airplane systems not functioning properly, the FAA said in the directives, which are effective July 1.

The directives require revisions to existing airplane flight manuals to incorporate limitations prohibiting some operations requiring radio altimeter data when operating in Canadian airspace.

The latest FAA action come just a few years after the airline industry and wireless carriers, such as AT&T Inc. and Verizon Communications Inc., clashed over the expansion of new 5G services.

The FAA said Transport Canada notified the agency in March that beginning July 1 changes to 5G protections, including the elimination of exclusion and protection zones at airports, that had been established by the Canadian government in 2023 “would result in a more severe 5G interference environment in the Canadian airspace.”

According to the agency, Boeing conducted an analysis and in May “reported that certain airplane configurations will not demonstrate tolerance to radio altimeter interference in the new 5G environment in Canada.”

Boeing didn’t immediately respond to a request for comment.

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