Airlines Face 5G Compliance Deadline on July 1

Since 2020, airline industry officials have voiced concerns that interference caused by 5G signals could possibly compromise radio altimeters aboard airliners, which can constitute a safety hazard in low-visibility situations.  

Data supplied by radio altimeters gives the pilot information about the aircraft height above terrain and supplies information for several other systems aboard sophisticated aircraft used by airlines. When this data is suspect, the aircraft cannot land.

Last week, Transportation Secretary Pete Buttigieg warned the nation’s airlines by letter that flights could be disrupted because some transport aircraft lack updated equipment to prevent interference from transmissions by 5G, The Associated Press reported. Buttigieg said that only planes retrofitted with the right equipment will be allowed to land when visibility is poor.

Wireless carriers AT&T (NYSE:T) and Verizon (NYSE:VZ) maintain that 5G is necessary as cellular data needs increase.

For the better part of two years, the manufacturers of radio altimeters have been working with OEMs Embraer, Boeing, Airbus, and Mitsubishi Heavy Industries to develop and test filters and installation kits for these aircraft. The kits are installed at the respective airline maintenance facilities, however, airlines have reported that supply chain challenges are making it difficult to meet the proposed deadlines for 5G activation.

In early 2022, a coalition of top aviation stakeholders, including Embraer, Boeing, Airbus, and the International Air Transport Association, asked for an extension of the July 1, 2023, deadline for large transport aircraft compliance.

As a stopgap measure, in January 2022 the wireless companies agreed to voluntarily reduce the power of the 5G towers near airports to help protect air traffic while the industry focused on developing protection for altimeters and later retrofitting the aircraft against interference.

In January 2023, the FAA proposed an airworthiness directive (AD) to require passenger and cargo aircraft in the U.S. be equipped with 5G C-Band tolerant altimeters or appropriate radio frequency filters by February 2024. The AD went into effect in May.

This was the second AD issued to address 5G issues in recent years as  AD 2021–23–12 "required revising the limitations section of the existing airplane/aircraft flight manual (AFM) to incorporate limitations prohibiting certain operations requiring radio altimeter data when in the presence of 5G C-Band interference as identified by Notices to Air Missions (NOTAMs)."

The current AD, as published in the Federal Register and effective as of May 26, supersedes the previous mandate, making the retrofits mandatory and requiring airlines to update their aircraft/airplane flight manuals "to incorporate limitations prohibiting these same operations at all airports for non-radio altimeter tolerant airplanes. For radio altimeter tolerant airplanes, the prohibited operations would be allowed at 5G C-Band mitigated airports (5G CMAs) as identified in an FAA Domestic Notice."

The airlines contacted by FLYING reported they will meet the FAA's Saturday deadline for 5G activation.

"All of American’s mainline in-service aircraft retrofits are complete, and we expect no operational impact," American Airlines said in a statement.

United Airlines also expects to have its mainline fleet fully retrofitted by the deadline.

Alaska Airlines completed upgraded radio altimeter modifications on all its Alaska and Horizon aircraft in June "ahead of the FAA’s July 1 deadline," the airline told FLYING. "It's an important safety milestone for us and critical to the reliability of our summer operations."

Carriers that have not yet finished the updates on their entire fleet, such as Delta Air Lines, will be turning to operational restrictions until they do.

"What this means for Delta is that some of our aircraft will have more restrictions for operations in inclement weather," the airline told FLYING in a statement. "Safety of flight will never be in question, and Delta will adhere to all directives and regulations from our regulators. Many Delta teams have been working to insulate any additional delays from our customers and people through strategic aircraft routing. While we expect minimal operational impact, we continue to work with our supplier to see that every Delta aircraft is equipped with updated radio altimeters.”

The Federal Communications Commission has previously stated that 5G will not interfere with airline traffic or compromise safety, but the FAA is taking a more cautious approach, publishing a web page with information about the impact of the cellular technology on air traffic. 

Wireless companies have pointed out that 5G is already in use in Europe and Japan with no issues. The FAA notes the conditions for 5G deployment in those countries are different than in the U.S. because of lower power levels, antennas differently placed and adjusted to reduce potential interference to flights, and frequencies with a different proximity to those used by aviation equipment.