FAA Ignores FCC, Limits U.S. 5G Over Unsubstantiated Safety Concerns

from the weird-standoffs dept

We’d already noted that the FAA had been pushing to impose limits on 5G deployments in certain bands due to safety concerns. The problem: the FCC, the agency with the expertise in spectrum interference, has repeatedly stated those concerns are unfounded based on the FCC’s own research. Worse, the FAA has proven a bit intractable in providing the FCC with data proving their claims of harm. The FAA claims that deploying 5G in the 3.7 to 3.98 GHz “C-Band” will cause interference with certain radio altimeters. But the FCC has shown that more than 40 countries have deployed 5G in this band with no evidence of harm.

That didn’t seem to sway the FAA, which prodded both AT&T and Verizon to pause deployment in the C-band. The FAA’s refusal to listen to the FCC, or be transparent about sharing any data to support its claims, has pissed off the FCC. To the point where a bipartisan coalition of six former agency commissioners and bosses wrote a joint letter politely tut-scolding the agency for being bull-headed:

We are concerned about the Federal Aviation Administration?s (FAA) recent efforts to revisit the FCC?s 2020 decision? to free airwaves for the fast 5G mobile service that?s to start next month, the six said in a letter dated Monday obtained by Bloomberg News.

?The FAA position threatens to derail the reasoned conclusions reached by the FCC after years of technical analysis and study,? the signers, a mix of Republicans and Democrats, said in the letter. They are Ajit Pai, Tom Wheeler, Mignon Clyburn, Julius Genachowski, Michael Copps and Michael Powell.

The weird thing is even one of the FAA’s own recent bulletins (pdf) states there are no “proven reports of harmful interference” with C-Band 5G deployments anywhere in the world. Despite no evidence of harm, the FCC was careful to set aside a 220 MHz guard band that will remain unused as a buffer to prevent this theoretical interference — technically double the amount manufacturers like Boeing requested. The FAA continues to maintain its claim, but so far has refused to provide the FCC with data proving it (but did manage to find time to leak its claims to the Wall Street Journal).

It’s a fairly bizarre feud caused by a stubborn agency that’s understandably so concerned about the faintest threat to public safety, it’s refusing to transparently work with the one agency that actually understands how the technology works. Harold Feld, who probably knows more about U.S. wireless spectrum policy than anybody in the country, has written a long primer here for anybody who’s interested.

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Comments on “FAA Ignores FCC, Limits U.S. 5G Over Unsubstantiated Safety Concerns”

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This comment has been deemed insightful by the community.
Ehud Gavron (profile) says:

FCC, FAA, and focus

Disclosure: I hold licenses from the FCC and certificates from the FAA.

The FCC’s focus is on communication, and safety isn’t even an afterthought since communication nowadays mostly works. Handheld GPS radio+SMS devices are sub $300… no problem.

The FAA’s focus is on aviation, and safety is a huge concern. The FAA has many programs to improve flight safety.

If the FCC makes an error, a communication may be affected. That doesn’t mean 40 countries doing something for a few months is anything other than anecdotal. Worse, a failure to communicate often results in a retransmission, not an incident report.

If the FAA makes an error, people could die (and no, I’m not being melodramatic here), and some of those PEOPLE DYING COULD BE CHILDREN. Collecting valid statistical data to prevent incident and accidents weighs a bit more heavily than "Oh, I guess you can’t hear me. I’m in a bad area. Let me try again."

So while I don’t think the FAA is flawless… nor do I think anything that the Ajit Pai FCC and its dregs is flawless… one is entrusted with with the lives of billions of flying public throughout the year, and the other is entrusted with enriching duopolies.

Not the same thing, and they should not be judged by the same gravitas of criteria.


This comment has been deemed insightful by the community.
hij (profile) says:

Re: FCC, FAA, and focus

You are right, if the FAA makes an error then it is catastrophic. That is the reason they should be forthcoming with their evidence of potential harm. As a federal oversight agency that safeguards people’s lives they should be diligent in gathering evidence and open to sharing their evidence in order to be transparent about their decisions. To make a decision that is contrary to the experience and practice of other countries and agencies without demonstrating harm is capricious and erodes confidence in an important agency.

TKnarr (profile) says:

Re: Re: FCC, FAA, and focus

I think one problem there is the standards used. The FCC uses the standard of "no evidence of harm", ie. things are assumed safe until proven otherwise. The FAA’s standard is "evidence of no harm", ie. things are assumed not-safe until proven safe. The FCC’s standard is fine when the worst that can happen is people are inconvenienced, but when lives are on the line you don’t want to hear a company saying "Well, there’s no proof our stuff was responsible.".

Scary Devil Monastery (profile) says:

Re: Re: FCC, FAA, and focus

"That is the reason they should be forthcoming with their evidence of potential harm."

As Tknarr has it, the FAA operates on a whitelist. The Napoleonic code, if you will. Their job description is literally to make sure every technology used within their bailiwick is proven safe beyond reasonable doubt.

That being the case when new tech is introduced their job is actually to say "You say this is safe? Prove it". Not for them to produce indications that it’s unsafe.

Objectively they have a point. Tech suppliers and OEM’s have been known to cut corners in myriads of "interesting" ways.

Also objectively; it’s still true that the FAA is a bureaucratic mini-empire, a state within the state and that being the case there will be bosses whose primary motivation is to flex.

Anonymous Coward says:

Re: FCC, FAA, and focus

Here is a commercial pilots explanation of the potential problem. It only affects fully blind auto landings, where the pilots do not expect to see the runway until they land on it. The radar is only used for the last few hundred feet of decent. Rather than a blanket ban, restrictions under flight paths would be more reasonable.

This comment has been deemed insightful by the community.
Al_D (profile) says:

Re: FCC, FAA, and focus

I’ve working in commercial aerospace for decades and first received the FAA bullet on this topic several months ago and recognized it as an obvious issue that would likely be resolve one of two ways.

  1. Manufactures of effected Radar Altimeters would asked to tested for interface when exposed to 5G transmitters, or more likely
  2. 5G transmitters would simply not be allowed within some distance of airport approach/departure routes, as this is the only time these devices are active.

Additionally, 5G only has a range of approximately 1000 feet and radar altimeters that are installed in private and commercial aircraft only provide valid data at altitude of 2500 feet of less. So simply restricting placement of 5G transmitters to within 5000 feet of airport’s approach and departure routes eliminates any chance of interference.

But why find a common-sense solution, when millions of tax dollars can be wasted?

Ehud Gavron (profile) says:

Re: FAA AD issued 20220126

Update: The FAA has issued an airworthiness directive (AD) to operators of Boeing 747 and 777 aircraft. This will require updates to procedures, the pilot’s operating handbook (POH), and training.

For all the "but it works in Europe" people the difference is that in the US the frequencies are different, provide less of a "buffer" (guard band) between 5G and radar altimeters, and the US regulator (FAA) is more rigorous in testing.

This AD should pretty much end the debate on whether 5G interferes with radalts. Yes, it does.

Chris-Mouse (profile) says:

The FAA isn’t concerned about finding data proving something is dangerous. They need to find data proving it is safe. The lack of proof does not mean lack of danger.

On the other hand, I can see why the FAA might be reluctant to accept any data from the FCC, given that organizations recent history of ignoring obvious fraud or basing decisions on bogus data

This comment has been deemed insightful by the community.
James Burkhardt (profile) says:

Re: Re:

You can’t prove something is safe. "safe" is a subjective assessment of risk. It can never be known if a 1 in a quintillion error would happen, and so any designation of safe is actually a determination that the risk of danger is low enough that we reasonably don’t expect danger. The scientific answer to "is this safe?" for something you or I considered safe would be that the evidence doesn’t establish that ‘this’ is dangerous. The claim that they have found no evidence of danger is the accurate statement.

Saying something is safe would be definitive, something we can’t genuinely know. Saying there is no evidence of danger means we have studied the danger posed and found the concerns wanting for evidence. In this case, over 40 countries have already implemented 5g in the bands indicated with no issue and we built a safety buffer double the size requested by the engineers. We don’t have to trust just FCC data, we can trust the FAA data, gathered from countries around the globe. It already is being done without issue. As noted above by an AC, restricting 5g deployments from the approach path would be all that is needed if there really was an interference issue….but again the data is in and the data does not show an interference issue. if the FAA has different data, it needs to show the reciepts.

JMT (profile) says:

Re: Re:

"The FAA isn’t concerned about finding data proving something is dangerous."

I’m pretty sure they are in fact concerned about finding data proving something is dangerous. It’s a pretty important part of their job.

And when a government agency claims something is dangerous, as the FAA is doing here, it is totally unacceptable to withhold the evidence of those claims from other agencies and the public. What possible legitimate reason could they have for doing so?

freelunch says:

time is needed for testing and making planes safe: 2008-2019

The multiband nature of 5G standards has been out there for over a decade. I first heard of it in 2008, and I don’t do this every day. Interested parties, such as the airline industry, weighed in on the FCC rules for it for years. The FAA now thinks further testing and adjustment is needed. Where were they when the issues were being decided? To come in now, after many billions of dollars have been spent in reliance on the regs, is not good government. There is an orderly process for interagency communication about future decisions to avoid messes like this. DOD and DOT are the least cooperative, in my experience, and through delay, the least responsible — soldiers will die if I don’t get to decide your policy for you, and planes will fall from the sky. No details needed, just the assertion that planes might fall, coming in decades late.

ECA (profile) says:

More fun to be had

"Nearly all C-band communication satellites use the band of frequencies from 3.7 to 4.2 GHz for their downlinks, and the band of frequencies from 5.925 to 6.425 GHz for their uplinks. Note that by using the band from 3.7 to 4.0 GHz, this C band overlaps somewhat with the IEEE S band for radars.""

"In response to a Notice of Proposed Rulemaking of July 2018 from the US Federal Communications Commission (FCC) to make the 3.7 to 4.2 GHz spectrum available for next-generation terrestrial fixed and mobile broadband services,[5] the C-Band Alliance (CBA) was established in September 2018 by the four satellite operators—Intelsat, SES, Eutelsat and Telesat—that provide the majority of C-band satellite services in the US, including media distribution reaching 100 million US households. The consortium made a proposal to the FCC to act as a facilitator for the clearing and repurposing of a 200 MHz portion of C-band spectrum to accelerate the deployment of next generation 5G services, while protecting incumbent users and their content distribution and data networks in the US from potential interference.[6][7]"

Good info.

Upstream (profile) says:

But the FCC has shown that more than 40 countries have deployed 5G in this band with no evidence of harm.

The Boeing 737 Max 8 planes did a lot of flying with no evidence of harm, either. For a while.

So simply restricting placement of 5G transmitters to within 5000 feet of airport’s approach and departure routes eliminates any chance of interference.

[I am ignoring the absurd meaning caused by grammatical / syntax / sentence structure errors.]

Radio frequency waves (RF waves aka TEM waves) are weird and wonderful things. Their propagation is affected by many factors, and distance is only one of them. For instance, an atmospheric phenomenon known as "tropospheric ducting" can cause VHF, UHF, and microwave frequencies, which usually only have line-of-sight range, to travel hundreds of miles. All of the 5G frequencies are within the range of frequencies that can experience tropospheric ducting.

Spurious emissions are also a very real thing. This is when RF transmitters emit power somewhat outside their intended frequency band. There is a phenomenon in RF transmitter antennas and their towers known as the "Rusty Bolt" effect. This is where, over time, the metal in an antenna tower experiences degradation and can create spurious emissions where none were present when the equipment was originally installed.

You could use directional antennas that do not point at airports But what if in the future someone erects a building that reflects those emissions back towards the airport?

Tropospheric ducting, "rusty bolt"-induced spurious emissions and unanticipated reflections are but three of many factors affecting RF signal propagation. There are many more. So simply limiting transmitter location, or saying "there haven’t been any problems yet" do not in any way provide assurance that there will not be any catastrophic problems in the future.

Annonymouse says:

Re: Re:

WRT the 737 Max the FAA didn’t drop the ball. They gave it to Boeing and let them keep score. That’s how a safety system that normally has three sensors had only one and no pilot assist overide in place in case of catastrophic failure. They didn’t even look over the drawings to catch the obvious blunder/cost cutting by Boeing.
The FAA has been more about thingy wagging than due diligence for a few decades now.. Forget about informed competent decision making either.

Upstream (profile) says:

Re: Re: Re:

All very true, Anonymouse.

I just used the 737 Max as an example of something where a flaw did not create a disaster immediately, since we were talking about aviation stuff. And, as you correctly pointed out, it’s flaws were so obvious that most any first-year engineering major should have seen them and waved big red flags.

The potential for problems arising from 5G interfering with radar altimeters involves many factors that are much more subtle and insidious. In theory, if a 5G deployment did interfere with a radar altimeter the result would be a go-around, and possibly having to divert the flight to an alternate airport. But we all know how often "in theory" translates very poorly to "in reality."

I think this is another case of $$ carrying more weight than safety concerns, resulting in a very flawed cost / risk / benefit analysis (which is another way the Boeing 737 Max was an apt comparison).

Anonymous Coward says:

Re: Re: Re:2 Re:

The difference is that, with 5G, we have data suggesting it does not cause the problem alleged.

No. We do not have data proving that it already has caused the the problems that the FAA and others legitimately theorize that it might cause in the future.

Big difference. Even more so if you fly on commercial airplanes that use the radar altimeter equipment that might be subject to the interference.

Anonymous Coward says:


Greetings to everyone: Stop using the FAA citing safety concerns for air travel. The spectrum HAS been allocated and is licensed for the purpose of providing 5G coverage world wide. This is property that has squatters have been notified over 2 years ago that they need to move. The specific concern is that Radio Altimeters will experience interference. The answer: FAA, enforce the law to require updated technology that changes to another band. The radio altimeters are NOT licensed and Must not cause interference to the licensed users. 5G C-band implementation includes technology that provides for vital data feeds for many advances in travel and Healthcare. FAA, Get with the program or get out of the way. Stop using the cheap technology and work with the FCC to move to a different band.

Ehud Gavron (profile) says:

Anonymous Coward:

Thanks for letting us all know what you command us to do. Sadly, you lack any expertise, authority, and authorization to demand we comply with your demands.

The public deserves the ability to be as safe as possible in their flights. That this doesn’t track well with FCC allocations is, as you point out, a reason to move, but not a demand for such, a deadline for such, or a requirement for such.

RADAR altimeters are a thing, and as of around 2018 (can’t find the exact date right now) a requirement not just for FAA Part 135 operators but also Part 121 and 91 LOA operators, and they were so excited to have to put in $10K/AC (aircraft) RADALT units it’s equally likely they’ll be just as excited to have those retro-fitted to another frequency band.

So get with the program yourself and stop telling other people to incur a $10K+ expense just because you think "work with the FCC" means something.

Go fix the republicans preventing minority votes and come back and pontificate.


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