The Federal Aviation Administration may be preparing to issue a warning to pilots and airlines about potential interference from new midband 5G networks, according to a report. And that situation could create a potentially significant obstacle to Verizon's overall hopes to dramatically improve its 5G network.

The Wall Street Journal reports that the nation's federal aviation regulatory agency is drafting a special bulletin warning that 5G transmissions in C-band spectrum could interfere with the radio altimeters used in everything from helicopters to commercial aircraft.

However, according to the report, the draft has not yet been finalized. An FAA spokesperson told the publication that the agency is working with other government officials "so that aviation and the newest generation of 5G cellular technology can safely coexist."

And an FCC spokesperson told the publication that the agency remains committed to ensuring air safety "while moving forward with the deployment of new technologies that support American business and consumer needs."

Verizon's C-band plan

Nonetheless, the possibility of a warning creates a major overhang for Verizon, which hopes to begin putting its vast C-band spectrum licenses to use as early as December. The company spent around $50 billion acquiring the licenses in an FCC auction earlier this year, and has committed another $10 billion toward equipment to put the licenses to use.

The reason for Verizon's massive spending is clear: Midband spectrum like the C-band appears ideal for 5G. Such spectrum supports both speedy connections and vast coverage areas. That's noteworthy considering US operators so far have mainly deployed 5G in low-band spectrum (widespread coverage but relatively slow speeds) and high-band, millimeter wave spectrum (fast but only available in small areas).

And the issue is key for Verizon considering its rival, T-Mobile, is already more than a year into its own deployment of midband 5G. T-Mobile said it covers around 180 million Americans with average speeds of 200 Mbit/s and above. Verizon can't match that without its C-band spectrum.

FCC vs FAA

The FCC's auction of C-band spectrum earlier this year raised a record $81 billion in winning bids, mainly from Verizon but also from AT&T and T-Mobile. Prior to that auction, the FCC said aviation operations should not suffer from "significant interference" from 5G in the C-band. However, after the close of the auction, a large group of major aerospace and airline companies began sounding the alarm that 5G in the C-band would indeed affect radio altimeters.

"Major disruptions to passenger air travel, commercial transport and critical helicopter operations can be expected from the rollout of 5G under the commission's order," the group wrote to the FCC recently.

According to the WSJ, the White House has begun mediating discussions on the topic between the FCC and the FAA. But if the issue snowballs into a major public relations issue, Verizon's plans to switch on 5G services in its C-band spectrum could be imperiled. And that would undoubtedly affect the company's wider 5G aspirations, from smartphone services to fixed wireless offerings.

"We look forward to a resolution," a spokesperson for Airlines for America told the WSJ.

Vendors ranging from Qualcomm to Ericsson have been discussing possible remedies.

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano