Representatives of the aviation industry met with staff at the FCC earlier this week to discuss steps the industry has taken to harden radar altimeter hardware in “thousands of aircraft” to ensure better performance near C-band wireless operations.

However, they’re also asking the agency to consider more permanent changes on the part of C-band licensees – namely, AT&T and Verizon – ahead of the next round of 5G C-band deployments in July and December of next year.

The FCC auctioned off C-band spectrum between 3.7-3.98 GHz in 2021, with Verizon and AT&T spending more than $45 billion and $23 billion, respectively, before clearing costs. But later in the year, the battle with the Federal Aviation Administration (FAA) and aviation industry turned into a fiasco, with aviation groups warning about potential plane crashes due to interference from C-band signals.  

The culprit: old radio altimeters in the 4.2-4.4 GHz band that lack proper filtering technology, despite a 220-megahertz guard band. The airline industry is racing to replace the old technology with modern, more precise equipment.

In June, the FAA announced that it would take another year to solve problems with altimeters on major airlines.

Now the airlines and aviation officials appear to making a bigger ask of the wireless carriers. 

In an October 3 filing with the FCC, the aviation industry said it’s “working hard to reach retrofit deadlines,” and that “codifying limits to telecom can help aviation make investments in retrofits safe and not at a risk.”

Airlines for America, Air Line Pilot Association International, American Airlines and Garmin International were among those represented in the meetings with staff from the FCC’s Office of Engineering and Technology, Office of General Counsel and the Wireless Telecommunications Bureau.

“Reasonable 5G network/equipment limits are feasible and would avoid aviation implementing costly additional mitigations that are unnecessary given 5G’s operational use cases,” the airline officials said in bullet points presented to the commission.  

The aviation industry listed some examples of what they think could be considered ahead of the next round of 5G deployments in July and December of 2023. Among them, under the heading “5G Antenna Uptilt Limit,” are:

• 25+ dBi gain makes a significant difference to interference calculations with aircraft if pointing up or down

• Temporary FAA/5G mitigations have applied an uptilt limit with no apparent issues

By way of background, the aviation officials said that on January 19, 2022, A Block licensees AT&T and Verizon agreed to maintain lower power levels and antenna tilt downs near major airports until July 2023. The service turn-up date in the B and C Blocks in the 46 Partial Economic Areas (PEAs) and in the A, B and C Blocks in the remaining 360 PEAs is December 5, 2023.

With those deadlines in mind, the FAA and the aviation industry (including airlines, airframe manufacturers and avionics manufacturers) have been implementing retrofits of radio altimeters to protect them from 5G interference, the filing stated.  

Verizon didn’t have a lot to say about the matter when Fierce asked for comment. “We are engaging in ongoing conversations with the FAA and are making good progress towards our goals,” the company said in a statement. Fierce also reached out to AT&T and will update this story with any comment from them.

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