Verizon, AT&T and T-Mobile collectively spent almost $100 billion on C-band spectrum licenses for 5G earlier this year. Now, just a few months before that spectrum is scheduled to be put to use commercially, a large group of major aerospace and airline companies is warning the FCC that 5G operations in that spectrum band could have disastrous effects on the nation's air travel.
"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.
The group's basic concern centers on how 5G operations in C-band spectrum could affect radio altimeters in aircraft. The wireless industry has generally rejected such interference concerns.
Nonetheless, the development casts a cloud over the hopes of AT&T and Verizon to supercharge their 5G aspirations with spectrum that would undoubtedly improve their services. While Verizon and AT&T today offer 5G services that generally aren't much faster than 4G, midband C-band spectrum promises to support much speedier connections across wide swaths of the country. Already T-Mobile is using similar midband spectrum – in the 2.5GHz band, just below the 3.7GHz C-band – to offer 5G download speeds around 350 Mbit/s.
That's likely why the FCC's C-band spectrum auction raised a record $81 billion in total bids – a figure that doesn't include billions of additional dollars operators are spending to free the spectrum quickly and to install C-band transmission radios around the country.
However, at least a portion of all that spending could be threatened by the aerospace and airline industry, which is warning that 5G transmissions in C-band spectrum could interfere with radio altimeters used in everything from helicopters to commercial aircraft.
"Such harmful interference could lead to an escalation of negative outcomes, from missed approaches, delays, diversions and flight cancellations, to the shutting down of runways on an indefinite basis," wrote a large number of airline and aerospace trade associations and companies including Aerospace Industries Association, Airlines for America, American Airlines, The Boeing Company and Lockheed Martin Corporation, among others. In meetings with FCC officials, the group also "discussed the critical role of accurate radar altitude during escape maneuvers that can be required by large commercial air transport and other aircraft during wind shear events and that occur near the ground. Loss of, or incorrect, radar altitude due to flexible use interference would greatly reduce chances of a successful safe outcome."
Radio altimeters help measure the altitude of an object and are common in aircraft of all types.
Dismissing the concerns
In previous filings to the FCC on the topic, the wireless industry has generally rejected such interference concerns. "The commission correctly determined that C-band 5G can operate without causing interference, let alone harmful interference, to neighboring services in nearby bands," the CTIA, the main trade group representing AT&T, Verizon and other major wireless companies, wrote in an April filing to the FCC. "The commission should dismiss the aviation industry's unsupported claims."
Importantly, the aerospace and airline companies argued that they're working to prevent interference by upgrading their radio altimeters with new filters, but that such efforts won't be enough. They said 5G network operators will also have to make modifications to their systems to prevent interference.
The aerospace and airline companies said the 5G industry has been unwilling to negotiate on the issue, and as a result they're calling on the FAA and FCC to step in to prevent "public harms."
This isn't the first time the FCC has made 5G spectrum rulings only to face warnings of interference afterward. For example, the FCC auctioned the 24GHz spectrum band for 5G only to be dealt concerns later that 5G operations in that band would affect weather forecasting. And Southern Company recently reported that operations in the 6GHz band – recently released by the FCC for unlicensed operations – could affect fixed wireless microwave connections.
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