Communication Breakdown: T&I Hearing Shows Differing Perspectives Between FAA and FCC on 5G and Aviation Safety

Reminiscent of a certain Led Zeppelin song, all witnesses and Representatives agreed on the utter lack of communication and coordination between the Federal Communication Commission (FCC) and Federal Aviation Administration (FAA), with the National Telecommunications and Information Administration (NTIA) in the middle regarding the issue of if/how 5G affects aviation.


Panel I:

Panel II:

FAA Administrator Dickson chose to have a kind-of “kumbaya” attitude, not wanting to point fingers or place blame, emphasizing communication and transparency while working together with the FCC and the telecommunications providers. But there was plenty of appetite in the hearing for blame-casting.


The FAA is reported to have been researching 5G since at least 2015. Dickson remarked that FAA engineers have been analyzing 5G since about 2018. FCC became interested in auctioning off parts C-band (at the behest of Congress, which always wants to be able to spend the billions of dollars brought in by spectrum auctions), and since they are a public agency, in 2018 had a public review period where anyone could submit comments. They received thousands of submissions, many from airlines and other aviation stakeholders, concerned about plans to auction off parts of the spectrum. In its comments, Boeing requested a “buffer zone” of empty airwaves between 5G spectrum and the aviation spectrum. The FCC typically has buffers of 5 to 10 MHz. Boeing asked for 100 MHz. The FCC made it 220 MHz: this is a very large compared to the buffer zones between other frequencies.

According to CNN, FAA did not submit comments to FCC during this review period. FAA only wrote to FCC in 2020, a year after the FCC had finalized its 5G airways authorization plan. This is after the FCC had spent two years soliciting information.

However, another key player is the NTIA. NTIA serves as the president’s advisor on telecommunications issues, and is also facilitate interagency communication on spectrum issues. Many representatives blamed the NTIA’s poor leadership under the Trump administration, as it was led by five temporary heads. In December 2020, the FAA and DOT sent a letter to the NTIA detailing its concerns of 5G deployment on aviation safety. This has become a controversy as NTIA Chair Adam Candeub left for a new DOJ job a few days after the letter was sent, and the letter was never delivered to the FCC. Candeub told CNN this was purposeful, because his “agency’s engineers disagreed with the letter’s conclusions,” an action which one former FCC official thinks is “disturbing.” While NTIA should have forwarded this letter to the FCC, FAA could have directly submitted the letter to the FCC, but chose not to.

Nevertheless, while the FAA did not communicate directly with the FCC, other aviation stakeholders were still advocating directly to FCC about 5G concerns. DePete and T&I chairman Peter DeFazio (D-OR) both remarked that airlines, pilots, manufacturers, the T&I subcommittee, and many other stakeholders voiced their concerns to the FCC. In November 2019, Rep. DeFazio wrote a letter to FCC Chair Ajit Pai, urging him to reconsider auctioning off C-band due to aviation safety concerns. Even though the NTIA did not deliver the letter from FAA to FCC, the FCC was clearly aware of this issue, argued Chair DeFazio. Yet, it there was no mention as to why the FAA did not write in during the FCC’s public request period in 2018.


Radio altimeters used on aircraft operate at 4.2 to 4.4 GHz. The FCC auctioned off part of the C-band, from 3.7 to 3.98 GHz, an attractive frequency because it has good coverage and power levels, noted Baker.

While the FAA has cleared 90 percent of altimeters, the remaining 10 percent are not cleared – most of these are smaller, older aircraft, mostly affecting regional airlines.

Roberson explained that older altimeters were made when there were very large buffer zones in the spectrum – therefore, engineers did not pay as much attention to spectrum limits. This means older altimeters have more potential for interference, as they can pick up signals from far outside the 4.2 to 4.4 GHz realm.

Timeline for altimeter replacement

Many Representatives asked about a timeline process for replacing altimeters prone to interference with new altimeters. However, Dickson said that will require a long testing and certification process before they can replace older models, estimating it would take at least a year, and possibly two, to certify altimeters that can replace older models prone to 5G interference. Even then, there will be questions on which altimeter models only need a new spectrum filter, and which ones need full replacement.

There could be an opportunity for funding – the FCC did this before when they paid TV broadcasters to move frequencies. Baker agreed that there is precedent for the FCC to use part of $81 billion to fund new altimeters. (Ed. Note: Congress may swoop in and direct the FAA how to use the windfall. Congress loves to order spectrum auctions to pay for new policies without raising taxes – directed spectrum auctions were a “pay-for” for the 2015 bipartisan budget deal and even last year’s infrastructure bill.)

Dickson confirmed that the FAA’s priority has been approving altimeters in large, commercial carriers. Because of this, regional airlines have been disproportionately affected as their smaller aircraft are still waiting for altimeter approvals.

In addition to the altimeters themselves, 5G interferences poses problems when there are low-visibility or otherwise sub-optimal landing conditions – also referred to as Category (CAT) II & III approaches. This is problematic because even if the FAA has cleared an altimeter itself to fly in a 5G zones, if there are low-visibility conditions along with 5G interference, it could make the aircraft unable to land safely, resulting in a flight diversion, told Black.

5G in the U.S. versus abroad

There was also much focus on how the 5G in the U.S. is more powerful than anywhere in the world (a fact that Baker denies). 5G is operative in France, Canada, the Czech Republic, etc., but all have more mitigation measures, said Rep. DeFazio and other witnesses. In France, said DePete, antennas are pointed down, stations transmit 1/3 of the power, and runway buffer zones are 2.5 times larger. Rep. DeFazio showed this chart, noting the differences between France and the U.S. DeFazio also noted that the U.K. believes 5G poses a “viable” threat to altimeters.


FAA has granted some commercial aircraft AMOCs (alternative method of compliance) – these are temporary (30-day orders but can be renewed) alternative safety measures that can be used to address an unsafe situation. However, the FAA must put out hundreds of AMOCs for specific aircraft models, landing approaches, even each airport. Calio criticized the constant churn of information how every 30-day changes where you can fly, when you can fly, what runway you can fly on, etc. Rep. Kahele (D-HI), as a commercial pilot himself, remarked how confusing this constantly changing information is, and advocated for a long-term solution instead of 30-day periods of flux.

While the FAA has published AMOCs for most large aircraft/conditions, Black argued that they have left regional carriers behind as 14 percent of the regional airline fleet has no AMOCs, and 40 percent of fleet has very limited AMOC. This affects 70 airports, many of which are regional hubs predominantly served by smaller aircraft.


There was also discussion on how 5G impacts helicopters. Particularly for air ambulance, many are currently flying in areas with significant 5G interference, said Viola.

FAA has not issued any AMOCs for helicopters. Because of this, HAI lobbied FAA for an “HAI exemption” where helicopters can operate in areas with 5G, given increased training and by using night vision goggles. Viola said 97 percent of the 1200 helicopters used for ambulance now are using the HAI exemption.

5G exclusion zones

The telecommunications firms considered the location of 5G towers to be proprietary information, said Rep. DeFazio, making it impossible for the FAA to analyze possible interference. By the time the airline industry found out that signals would be close to airports, the towers were already built.

At the urging of the FAA, the airlines, and the White House, the telecommunication firms agreed to voluntarily suspend 5G towers near airports for the next six months, with airlines asking for a two-mile buffer zone (or the equivalent of the last 20 seconds of flight). However, some have plans to turn more on before that (though this is mostly because of working with the FAA to refine buffer zones).

Almost everyone in this hearing was pro-buffer zone except for Rep. Chuy Garcia (D-IL). Because his constituent within the two-mile zone around Chicago Midway are primarily Black and Latino with very poor broadband access, 5G is essential as cell phone service is their primary way of accessing the internet.


Many in the hearing blamed this debacle on the differing cultures and priorities of the FCC and FAA. The difference in departmental ethos is dramatic: while the FCC believes that 5G is safe until proved otherwise, the FAA believes that because 5G has the potential to interfere with aircraft altimeters, the technology is unsafe for use until it is absolutely proven that there is no interference. The FAA not willing to risk the lives of the flying public.

Many referenced the 2020 RTCA study – Baker and Roberson claimed that the study was flawed as it included all the worst case scenarios. Larsen and DeFazio sharply criticized this view, with Rep. Larsen (D-WA) saying aviation is “business of improbable scenarios.” Rep. DeFazio mentioned how the 737-MAX tragedies were considered worst case scenarios until they became reality.

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