FAA Urges Airlines to Retrofit Altimeters Ahead of 5G Signal Increase

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The FAA on Wednesday urged the chief executives of major U.S. airlines to move quickly to address risks from a 5G wireless rollout by retrofitting their radio altimeters. It’s a bid to avoid potential disruptions at key airports next month.

Acting FAA Administrator Billy Nolen said in a letter reviewed by Reuters that AT&T and Verizon want to begin transmitting 5G operations on C-band frequencies in July using some towers around airports that had been depowered and restoring others to full strength. The carriers delayed those operations twice to give the airlines more time to upgrade or fix radio altimeters. The last delay was for six months, which ends July 5. That date “is rapidly approaching,” Nolen wrote. 

Radio altimeters tell pilots how close the plane is to the ground; they’re crucial for bad weather landings, according to Reuters. Concerns that 5G service could cause harmful RF interference with altimeters on nearby frequencies, led to disruptions at some U.S. airports earlier this year.

Nolen urged airlines to urgently press ahead with retrofitting radio altimeters, saying “there are no guarantees that all large markets will retain the current [safeguards].” He warned that as wireless carriers boost signals, some “less capable aircraft” may be unable to access certain airports without altimeter retrofits during inclement weather.

In recent months, the FAA has been urging airlines to complete retrofits of some airplane radio altimeters that could face interference from C-band 5G operations by the end of 2022. The FAA said it’s in the early stages of working with AT&T and Verizon “to identify markets where either a new tower or an increase in signal power will cause the least disruption,” Reuters reported.

Nolen said in three recent rounds of talks, industry officials identified a pathway to retrofit the first two groups of aircraft with the most vulnerable radio altimeters by the end of the year. Another round of talks is set for today. “We are working toward an equally aggressive schedule that would necessitate the completion of retrofits for the third and largest group in 2023,” Nolen said. He added that “as the situation stands, Verizon and AT&T plan to pursue a full rollout of their networks by the end of 2023.”

Another 19 radio altimeter manufacturers “are expected to enter the market during that time frame, hopefully employing some level of the voluntary mitigations that have enabled our progress so far,” he added.

Verizon said it was working with the FAA, FCC and aviation industry, and was confident it would achieve “robust deployment of C-band without significant disruptions to the traveling public.” AT&T did not comment.

Airlines for America, an industry trade group representing American Airlines, Delta Air Lines, United Airlines and others, said the industry recognized the need “to implement a permanent solution, while continuing to ensure the highest level of safety.” Some airlines have raised concerns about paying to retrofit altimeters only to face paying for a replacement in a few years. Nolen said, “without additional action by the FCC to cap transmissions at currently attainable power levels, the prospect of additional disruption remains and we are not in any position to offer assurances.”

By Leslie Stimson, Inside Towers Washington Bureau Chief

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