AT&T, Verizon delay 5G C-band rollout over FAA fears of passenger plane radars jammed by signals

AT&T and Verizon have agreed to further delay the US rollout of their previously delayed 5G C-band wireless service only one day before the planned launch date. On December 31, 2021, US Secretary of Transportation Secretary Pete Buttigieg and Federal Aviation Administration chief Steve Dickinson sent a letter [PDF] to AT&T CEO …

[Steve Aubrey]

He said, she said

Without technical clarity, there is no clear way forward. Based on the frequencies shown, it would seem that the telcos hold the winning hand. The government waiting so late in the game (and going all the way back to potentially licensing something unusable) is suspect. Seems like something more than the invisible hand of capitalism is at work.

[martinusher]

Re: He said, she said

This isn't the first time this has happened. The low end of the 5GHz WiFi band coincides with some airport ground approach radars. Fortunately the pulses emitted by such radars look like badly formed WiFi packets to 802.11a hardware so one requirement of the drivers for this hardware is that it scans for these pulses on startup and keeps clear of that part of the spectrum. Its a bit of a kludge but it seems to work.

I'd guess that the telcos will either not use this part of the spectrum near airports or install a similar firmware kludge.

Its worth noting that despite its ultra-high tech image the world of aviation is hyper-conservative, it never throws anything away so it still uses electronics technologies that were first developed 80 years or more ago. Agencies like the FAA take a long time to depreciate obsolete technologies -- things might become unused or even stop working (and nobody noticed it) but its still regarded as essential knowledge for pilots and any frequencies used are defended against any kind of incursion on safety grounds.

[David 132]

Re: He said, she said

Yeah. After reading up on this and carefully trying (as a layman) to parse the arguments, I have to side with AT&T and Verizon here.

(GOD you have no idea how dirty typing that last part makes me feel.)

[Jim Mitchell]

Why only major airports? If this is a real issue, that makes it seem OK if planes crash at smaller airports.

Also, if I die due a radio altimeter failing due to interference, my ghost is suing the airline for not getting a better radio altimeter, not AT&T.

[David 132]

You’d have to get a ghost lawyer. And you’d lose, because courts respect the letter, not the Spirit of the law.

[John Brown (no body)]

<groan> very good :-)

[a_yank_lurker]

Altimeters

If the issue is interference with radio altimeters, why wouldn't this affect them in other areas as well as near an airport. If the reported altitude is incorrect, pilots are going to try get their assigned altitude. If they are flying on instruments this could lead to all sorts of accidents and near misses; assuming the problem is real. Also, 2nd or 3rd harmonics of the signals would be an issue around an airport; I have not looked up what is assigned those frequencies. The 2 bands are not harmonically related.

[doublelayer]

Re: Altimeters

Assuming there's a real problem*, it's still probably unimportant outside airport range because the planes will be much higher when flying over that area. The towers are only located at ground level, so the signal strength would be much lower. During takeoff and landing, the planes will be much closer to towers.

*I am not an expert in this, but I have not heard any convincing explanation why this band would interfere with altimeters. Without technical knowledge, the mobile companies' statements seem a lot more logical.

[JimboSmith]

Re: Altimeters

If the issue is interference with radio altimeters, why wouldn't this affect them in other areas as well as near an airport. If the reported altitude is incorrect, pilots are going to try get their assigned altitude. If they are flying on instruments this could lead to all sorts of accidents and near misses; assuming the problem is real. Also, 2nd or 3rd harmonics of the signals would be an issue around an airport; I have not looked up what is assigned those frequencies. The 2 bands are not harmonically related.

I may well be wrong but my recollection is that radio altimeters don’t work above a certain height from the ground, 3000ft? Therefore the problem would be greatest near airports where the planes will be closest to the ground. I’m sure a pilot will be along shortly to correct me.

[werdsmith]

Re: Altimeters

They are a critical part of the approach and landing for low visibility and autoland approaches where they give the accuracy needed that a pressure altimeter can't. At higher alitutudes, altitude is based on a standard pressure which separate aircraft by flight levels, and may not necessarily be the actual height above ground level, because it is affected by change in the weather systems. But the same for all aircraft relative to each other.

[David 132]

Re: Altimeters

> greatest near airports where the planes will be closest to the ground

…you hope.

[martinusher]

Re: Altimeters

They're only used during the final stages of landing where a precise knowledge of how far you are from the ground is needed. Normally height will be provided by GPS or traditional altimeters.

It would be helpful if people talked about specifics rather than just hints. What's interfering with what, exactly, and how does this interference manifest itself, that sort of thing.

[Pirate Dave]

Come on, El Reg, you left off the end of the quote...

"Agreeing to your proposal would not only be an unprecedented and unwarranted circumvention of the due process and checks and balances carefully crafted in the structure of our democracy, but an irresponsible abdication of the operating control required to deploy world-class and globally competitive communications networks that are every bit as essential to our country's economic vitality, public safety and national interests as the airline industry, As well, your mother was a hamster, and your father smelt of elderberries."

Why is everything suddenly a threat to our (US) democracy? Or is that just the new, hip way of saying "think of the children"?

[sabroni]

re: Why is everything suddenly a threat to our (US) democracy?

Because it's hanging on by the skin of it's teeth. Nearly half your population don't believe your democracy works but they have unwavering faith in semi-automatic firearms.

Why would you think democracy isn't under threat the USA?

[Pirate Dave]

Re: re: Why is everything suddenly a threat to our (US) democracy?

Well, I'll admit, my semi-automatic firearms rarely disappoint me; politicians, not so much.

It's not so much whether it is or isn't under threat, it's why is that suddenly the catch-phrase? Sure, democracy in the US has been under threat pretty much since the country was founded, that's nothing new. But it perseveres and marches on in one form or another, wearing whatever the latest fashion is in politics, but still democracy underneath.

[martinusher]

Re: re: Why is everything suddenly a threat to our (US) democracy?

There's always been people advocating non-democratic rule such as the Birchers but the core of the political parties has always rejected them. What's changed is that what once were views held by fringe elements have now become mainstream in one party. Back during Bush 2 the notion of the "unitary executive", the idea that both the judiciary and legislative branches of government deferred to the executive branch with the President being above the law. This was widely derided at the time but a dozen years later it came back with a vengeance and is now Republican party policy. This, combined with the politicization of administration (culminating in the nearly successful attempt to make the senior levels of the Federal civil service subservient to the president by removing civil service protections and making employees 'at will') is leading the way to a fascist government in the US.

Obviously, as we all know "It can't happen here". We;ll keep repeating this until one day we find it did. Then it might be a bit late to do anything about it (but since I can pass for a Good 'ole Boy I daresay I'll leave it to all those people who blather on about Nazis but can't recognize a fascist when they're staring one in the face to deal with).

[Pirate Dave]

Re: re: Why is everything suddenly a threat to our (US) democracy?

"removing civil service protections and making employees 'at will'"

Having dealt with some of the sterling examples of Federal civil servants, I can't say that's necessarily a Bad Thing (tm). Lazy or incompetent, I don't know. I just know that some of them seem to think that "working" isn't actually part of "going to work". But hey, they're untouchable once they get in, no matter how poor they are at customer service, so they have no reason to tone-down the disdain. Just my experience though.

[Anonymous Coward]

Re: re: Why is everything suddenly a threat to our (US) democracy?

Because people have confused democracy with getting their way. Democracy means we hold elections, allow everyone to vote who is eligible and no one else, count votes completely and accurately, and respect the results. Far too many people -- mostly but not exclusively the hard-left -- are now using it to mean "elections have the outcome I think is obviously best", and in this case the telco CEOs are using it to mean "we get to turn on our equipment".

While in this case I agree with the telcos on the underlying issue, they are also abusing the word and that has cost them whatever good will I might otherwise have offered. Democracy does not mean that you personally get what you want, and not getting your way does not mean democracy is under threat. It's gotten to the point now that I pretty much always mentally replace "this is a threat to democracy!" with "I'm not getting my way so I'm going to whine and be melodramatic now". In that sense it's very much this decade's "think of the children" or if you prefer it's the same kind of language abuse as saying that anyone who disagrees with you is "worse than Hitler!".

Isn't it bad enough that you bought a license for this band for $80b from the government after a lengthy technical review process and are now being deprived by that same government of your right to use it in the exact manner prescribed by the license? And by the way, the people who are depriving them of that right were appointed, not elected, by the very President the "omg democracy!" whiners wanted in office. If their point is that SecTrans and the FCC commissioners should be elected instead of appointed by the President, that's a valid position to take but doesn't really explain why they think it would address this particular problem. That would be an opportunity to expand democracy, not a threat to it; those positions have never been elected.

Hopefully that answers the question.

[Someone Else]

Re: re: Why is everything suddenly a threat to our (US) democracy?

Far too many people -- mostly but not exclusively the hard-left -- are now using it to mean "elections have the outcome I think is obviously best", [...].

I had no idea that tRump, Nunes, Ghomert, Meadows, Cruz, Hawley, Graham, Cawthorn, et al were considered "hard left".

I guess you learn something new stupid every day!

[Pirate Dave]

Re: re: Why is everything suddenly a threat to our (US) democracy?

Don't forget Madonna. Or Kathy Griffin. Or most of Hollywood in 2017. All disagreeing with the results of the 2016 election. All the masturbatory marches, the rallies, and the constant denigration of everyone who voted for the Orange Guy. Don't forget Dave Chappell almost getting ostracized for daring to say that we needed to give Orange Guy a chance. I think THAT'S the "hard left" he's talking about.

[Robert 22]

If the radar altimeter band is different and not harmonically related, I have difficulty seeing what the issue is. I suppose that there is the possibility that strong signals could overload and desensitize the radar altimeter, but I would expect that there should be good bandpass filtering at its input.

I would have thought that it would be fairly easy to demonstrate the potential for problems in a lab environment, but see no indications that this has been done. Is everything just speculation???

[42656e4d203239]

>>but I would expect that there should be good bandpass filtering at its input.

That, I think, is the point... you would _expect_ the altimeter to have good bandpass filtering but it may well not have any - after all before 5G came along the altimeters were not expecting any sort of signal remotely close to their nominal operating frequency, other than thier own.

It does seem odd, to me, that the FAA has waited so long to make their concerns known but the 5G pushers are also slightly off in their "think of the children" response and their apparent "Ah.. it will be OK... don't worry about it; if there is an accident related to 5G then our lawyers are paid more than yours and, anyway, if the FAA has approved the bandwidth use then it is their problem not ours" approach.

As someone else said above, it all seems a little fishy - at least it does to this particular greybeard.

[_LC_]

Why is this always turned into a “5G issue”?

5G is just a protocol. It's not bound to specific frequencies. In fact, they vary from country to country.

It's the frequency that creates the problem here. 4G, 3G or 2G on those frequencies would create the same problem.

[Snar]

I would also have expected decent bandpass filtering on the input of an altimeter RX. If this was to be an issue then why wasn't it raised before $80Bn was taken from the sale of the spectrum? I would have thought that the FAA would have screamed loudly when the spectrum was up for sale?

I remember years ago hearing that the CAA had a massive issue with PLT power line comms in the UK but failed to do anything about it.

You can't allow companies to bid and legitimately purchase spectrum and then whinge that it may be an issue once the deal is done. I don't know how spectrum sale operates in the US, but there must be a due process to allow other spectrum stakeholders to raise concerns.

I was of the impression that getting flight approval was one of the hardest to achieve - maybe I'm wrong. I would have expected a good level of bandpass filtering if the altimeters are critical for fight approval. Maybe someone more knowledgeable of the regulations can put me right.

And that's from another greybeard :)

[Norman123]

How come other countries have overcome this issue for the past at least five years. Is Corporate America falling behind with all the pile of weal/resources at their disposal?

[_LC_]

Read my comment from above.

[Anonymous Coward]

From TFA:

"...adopt C-band signal level reduction zones similar to those implemented around airport runways in France"

[Gene Cash]

Captain Joe DePete

That's a classic "baffle 'em with bullshit" statement if I ever heard one. I'd respect the FAA and the airline industry if they didn't blather and bloviate like that. You only do that if you don't have an actual position to defend.

The "real work" should have begun on this years ago, if it's an actual issue.

Remember all the "turn your phone off before you crash the plane!" that turned out to be complete bullshit and there was never any interference noted from cellphones?

As much as I hate AT&T and Verizon, I think they're in the right on this one.

[JimboSmith]

Re: Captain Joe DePete

To me part of the issue here is that the FAA and Boeing have not had a good reputation over their handling and certification of the 737Max. As a result I suspect they're being ultra cautious over anything that could compromise safety. Although I don't know and can't think why there's been such a delay in bringing this issue to the table.

[Snar]

Re: Captain Joe DePete

Would that be shit design on the part of the contractors? Cutting costs?

Challenger go at throttle up!

[Anonymous Coward]

Re: Captain Joe DePete

"and there was never any interference noted from cellphones?"

Why do you say there never was any interference from cellphones?

While I'm not aware of any crashes or significant incidents, I do personally know someone who spent a great deal of time fighting cellphone interference in an aviation system (granted, he was with a Part 91 manufacturer).

[Anonymous Coward]

Empirical evidence?

Those frequencies - while not the most commonly used part of C band - are already deployed elsewhere in the world. I'm sure someone would have noticed planes crashing by now.

[werdsmith]

Re: Empirical evidence?

Planes crashing or just inconsistent radar altimeter readings compared to eyeball on approach.

[spireite]

Wait, surely Boeing need 5G to be implemented.

They can stream live UHD from inside the Boeing Lawn Dart to prove it's safety.

[Anonymous Coward]

A couple of points.

1. I would not really be surprised if the radio altimeters didn't have too much band filtering - until now, that part of the spectrum wasn't really used too much so why would they add the cost?

2. Most of the decision making on this issue would have occurred under previous (US) government and FCC administration. Similar problems occurred with GPS systems and '4G' transmitter spectrum allocation (and are also still ongoing).

3. The FAA appears to have been under some constraints - resulting in the 737-MAX certification fustercluck. Prior to that we had the battery issue.

4. There seems to (have been ?) a bit of a disconnect between a number of US government agencies. This may have been fall-out results from lack of communication between FAA & FCC & ??

Just my reading of it.

[Someone Else]

Blah, blah, blah, etc.

From the article:

"Agreeing to your proposal would not only be an unprecedented and unwarranted circumvention of the due process and checks and balances carefully crafted in the structure of our democracy, but an irresponsible abdication of the operating control required to deploy world-class and globally competitive communications networks that are every bit as essential to our country's economic vitality, public safety and national interests as the airline industry," the CEOs' letter says.

Another dose of blatherskite bullshit uttered by a C-suiter whose only real "national interest" is his next bonus and stock option bolus.

_{And to whom any real damage to the airline industry can be considered "collateral damage" in the quest for said bonus and options.}