FAA Goes in Hard to Kill Mid-Band 5G

The Federal Aviation Administration (FAA) pulled a near-nuclear option to stop the rollout of $80 billion in new 5G airwaves yesterday, with new regulations that could cause widespread flight delays.

The new regs, as The Verge reports, would limit airplanes' ability to land at airports near C-band 5G equipment in poor weather, based on the agency's assertion that the new 5G frequencies will imperil the use of radio altimeters, which measure airplanes' distance from the ground.

C-band frequencies are key to Verizon and AT&T having any kind of differentiated 5G performance from their 4G systems. Currently, both carriers' “nationwide” 5G runs on former 3G or 4G airwaves, making their 5G performance not much different from 4G, as our Fastest Mobile Networks tests found.

C-band, and its sibling spectrum in the 3.45-3.55GHz range, which is currently being auctioned, were supposed to solve that problem by letting the carriers use larger, 5G-exclusive channels. Verizon has previously said it intends to cover 100 million Americans with C-band by the end of the first quarter of 2022, including many of the nation's largest metro areas.

No proposed mitigation so far can solve the problem, the FAA asserts, even though AT&T and Verizon have offered to reduce power levels.

This could all be performative. FAA Administrator Steve Dickson told the Senate Commerce Committee on Nov. 3 that “we will figure this out so 5G and aviation safety can coexist,” which implies a different position than “kill the 5G or we're shutting down flights.”

Similar frequencies are currently used for 5G in more than 40 countries without any noticeable effect on air traffic. There is a 220MHz guard band between the 5G frequencies to be used in the US and the frequencies the altimeters are supposed to detect. Conflicting reports from the US aviation and wireless industries assert that C-Band 5G either will or will not interfere with aircraft.

The FAA's move came on the same day new FCC Chair Jessica Rosenworcel was confirmed by the Senate. The FCC seems caught on the back foot by the FAA's obstinacy on the issue.

None of this controversy was priced into the C-band auction, the nation's most expensive at more than $80 billion, when it was conducted in late 2020 and early 2021. At the time, then-Chairman Ajit Pai's FCC blew off FAA concerns and declared smooth sailing on the C-band.