The FAA’s 5G C-band bans, explained

C-band spectrum is highly favorable for 5G, but the FAA is worried it may interfere with cockpit systems.
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5G’s rollout is entering airplane mode.

Last Tuesday, the FAA set flight restrictions for its pilots over fears that 5G carried over C-band spectrum has the potential to interfere with some cockpit safety systems. The FAA order prohibits pilots from operating automatic landing systems and other cockpit systems commonly used in poor weather, over concerns C-band spectrum could hamper their effectiveness.

  • The agency said it would notify airports that might face potential disruptions and interference in the future.

AT&T and Verizon voluntarily put their implementation of 5G C-band spectrum on hold to allow more time for the FAA to study the impact the deployment might have on airplane safety. The original timeline was to activate the new wireless service on December 5, but both companies delayed their rollouts to January 5.

  • The telcos also committed to lowering the power emitted from existing 5G cell towers that use C-band spectrum for six months, another precautionary measure to ease FAA concerns.
  • The FAA also says 5G C-band has the potential to interfere with radar or radio altimeters, which measure the distance between aircraft and the ground.

Telco giants AT&T and Verizon, which collectively spent almost $70 billion in a C-band bidding war in February, in an attempt to catch up to mid-band leader T-Mobile, said the FAA’s claims had no evidence.

  • The FCC, which oversees spectrum auctions and generally regulates radio, television, wire, satellite, and cable transmissions, looked into the issue last year and found no evidence of harmful interference with aircraft.

Uh, what is C-band anyway?

C-band is all frequencies of the electromagnetic spectrum measured between 4 Ghz and 8 Ghz; but the sweet spot of C-band that Verizon and AT&T are buying up is between 3.7 to 3.98GHz. That is used by satellite transmissions, wifi devices, and weather.

  • It’s highly favorable for 5G networks because they need broad, directed channels to enable the fast transmission they’ve promised.

“The thing about mid-band spectrum is that it is very fast, there’s a lot of it, and it covers a lot of geography with just a small number of towers. It’s called the ‘Goldilocks spectrum,’ because it has all of those characteristics,” Mike Dano, editorial director of 5G and mobile strategies at Light Reading, told Emerging Tech Brew.

  • Most 5G phones carried by Verizon and AT&T in 2021 should have C-band support, including iPhone 12s and 13s, Samsung Galaxy S21 series, the Google Pixel 5, and the LG Wing.

Big picture: Despite the delay in the rollout, the FCC has kicked some incumbent operators out of C-band. Satellite operators like Intelsat and SES had until Dec. 5 to vacate the spectrum in order to receive incentives from the FCC. Intelsat and SES are set to receive $4.9 billion and $3.97 billion for their troubles, respectively.

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