U.S. FAA clears 45% of commercial plane fleet after 5G deployed
reuters.com
reuters.com
Although, I guess papers like this detail the issue more carefully: https://ecfsapi.fcc.gov/file/7021340930.pdf https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-In...
Lower power levels and a downward tilt on the antennas would mean less range for C-Band networks so carriers would rather not do that - especially in the US where the population is much more suburban and rural than Europe.
It's possible that C-Band won't interfere even at higher power levels and even without downward antenna tilts. However, other countries have mandated greater permanent restrictions on C-Band than the US's temporary 6-month measures.
Source: https://www.lightreading.com/5g/why-does-5g-only-pose-a-prob...?
As noted in the article you posted, Canada is requiring antenna down-tilting nationwide as well as exclusion zones around airports.
EDIT: "an exclusion band is allowed ±10% around the band, within which the HIRF levels are very low—for radar altimeters, this spans 3.78–4.84 GHz"
https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-In...
So, in Europe, their C-Band ends at 3.8GHz and barely enters the range. In the US where we're going to 3.98GHz, we're well into that range.
It looks like Korea's band ends at 3.7GHz which is outside the range (and definitely by 3.8GHz which is where band N78 ends; the US is using Band N77 which ends at 4.2GHz, but we've only licensed spectrum to 3.98GHz)
These altimeters are dangerously defective if they need a 400mhz guard band. That is nuts
* LTE is very noisy (it has echos in its sidebands for up to 100Mhz)
* low-frequency LTE is *loud* -- punch through mountains loud.
* These altimiters are doing the RF equivalent of looking for a needle in a haystream
While FCC Part15 says "accept any/produce as little as possible", much of this comes down to the physics of RF.
https://www.commscope.com/blog/2021/maximizing-c-band-deploy...
https://www.airlines.org/5g-frequently-asked-questions/
In Europe, the power output seems to be ~2.5 time lower, there's a bigger frequency separation in Europe, the 5G towers are placed further away from approaches, and the antennas have to point downwards.
Still, this chatter will no doubt give some loon some ideas on how to bring down a plane or mess around with the flight patterns at busy airports.
And does it really matter if the US Mil own the spectrum? Thats like me saying the UK Govt owns the spectrum, they should still both be subjected to the court of law, if the laws are fit for purpose in the first place!
This can be a feature, not necessarily a bug.
There are plenty of examples of government central planning and cohesion going very wrong.
https://www.theverge.com/2021/11/24/22801008/verizon-att-mid...
I've flown a GA aircraft all around the lower 48, and only get a cell phone signal briefly when flying directly over a cell tower.
That said, you do get the occasional misaligned antenna or weird bounce off terrain that gets you signal midflight for a minute.
I'm not sympathetic to the airlines right now.
The FAA waited until December to issue airworthiness directives that limit the ability of the airlines to rely on radar altimeters under certain circumstances. The background here appears to be some kind of pissing match between US government agencies including the FAA, the FCC and the NTIA.
What exactly do you think the airlines were supposed to do here? Go out and have all their radar altimeters replaced? Replaced with what? The required standards haven't changed, and it's the FAA that writes the standard (technical service orders).
This is also not a "smoke testing" problem. This is a "on the worst day, in the worst set of circumstances, what is the degree of compromise of the assumed safety margins" question.
maybe the airlines should temporarily reassign the teams that redesign seating arrangements to reduce spacing to allow more people onboard. they seem very efficient at their tasks, and there's really not much left for them to do
"Interference as a singular cause appears to be extremely improbable."
Interference is mentioned a few times in the report as likely not being the cause or at least sole cause. The only entity seeming to push interference as a cause was Boeing, which led to this remark:
"We are not aware that interference has been conclusively identified as the explanation for the radio altimeter anomalies. In fact, some airlines have found that their incidence of radio altimeter anomalies decreased when they chose to install the new gaskets. If the conclusions here are intended to be DSB conclusions, rather than conclusions of Boeing and the airlines, the text should be revised to indicate they are DSB conclusions." in which they struck out the text "The negative values of the radio height were an indication of interference"
Was it due to interference? Otherwise this seems specious.
The Wikipedia entry [1] has a good overview, as does this Medium post [2]. In the flight 1951 crash there were actually 2 altimeters for redundancy, but due to human error they were configured so that 1 faulty altimeter affected the autothrottle:
> While on final approach for landing, the aircraft was about 2,000 ft (610 m) above ground, when the left-hand (captain's) radio altimeter suddenly changed from 1,950 feet (590 m) to read −8 feet (−2.4 m) height, although the right-hand (co-pilot's) radio altimeter functioned correctly. The voice recording showed that the crew was given an audible warning signal (landing gear warning horn) that indicated that the aircraft's landing gear should be down, as the aircraft was, according to the captain's radio altimeter, flying too low. This happened several times during the approach to Schiphol. The reason that the captain's radio altimeter was causing problems was the first officer making a mistake when arming the aircraft's autopilot system for a dual channel approach.
> The Boeing 737NG type aircraft has two autopilot systems, which can work independently of each other (single channel) or together (dual channel). Turkish Airlines' standard operating procedure at the time stated that all approaches should be flown "dual channel" when available, but the inexperienced first officer forgot to arm approach mode in the aircraft's mode control panel (which controls the autopilot), meaning that the aircraft thought the pilots wanted to do a single-channel approach using control computer A (captain's autopilot), which had a radio altimeter failure.
[1] https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951
[2] https://admiralcloudberg.medium.com/test-article-the-crash-o...
I note that the accident report on the Turkish airplane further confirms what we have since learned about Boeing:
* persistent issues with radar altimiters in the entire fleet
* issue classed 'low priority', even if it feeds into autothrottle
* near-crash results in 'fix' that disables autothrotle if two sensors disagree.
* 'fix' is not rolled out to the entire fleet. And it is not 100% effective.
* issue is not mentioned in documentation, pilots can not see which sensor is used
Is it me, or is this exactly the same history as MCAS? Drives home the famous mantra "if it's a Boeing, I'm not going"
He is very through and detailed, an instructor pilot with a lot of experience.
It is. And increasingly so in fact, as it allows more airports that don't have the resources to install and maintain ground-based equipment to have previously unavailable approaches. https://www.flyingmag.com/everything-you-need-to-know-about-...
However, it doesn't fall into exactly the same class as ILS approaches.
In good conditions the approaches might be indistinguishable, especially given that GPS approach once on final will be usually a copy of GPS one, but the safety of GPS LPV is considered much lower, for a good reason.
WAAS (GPS plus a correction signal transmitted by separate geostationary satellites) improves the resolution to CAT I standards - an "LPV" approach. However, it's still not sufficient for CAT II/III approaches.
A CAT III ILS approach requires very specialized equipment and training because you basically fly it all the way down to the runway with no requirement for visibility until moments before touchdown.
However, GPS is a lot better when it is not being obstructed by buildings around you. Planes have the benefit of unobstructed paths to GPS satellites and would get a better quality and accuracy then you might get with a phone in a city. Also, using good antennas helps. So, the altitude accuracy would be fine mostly.
I.e. the transmitter on the ground must be able to detect that something is wrong and immediately cut out the signal / report it as inop to the receiver on the plane. When you're seconds from hitting the ground, that is a requirement.
Although GPS based approaches have some aspects of this, I believe that they just don't meet the exact requirements as written currently, although they are close.
ICAO recognizes SBAS Cat I as a precision approach, and there are dozens of them in Europe (France, Austria at least).
See the following from gps.gov: it can be accurate to within centimeters and with a high polling rate, but most consumer devices don't employ the necessary tricks. https://www.gps.gov/systems/gps/performance/accuracy/
The highest resolution GPS receiver I have still has +/-15ns jitter, which over the course of a day is good enough for maybe 12-20cm resolution, but the first hour the track is wild, 50-80 meters off in varying directions.
My GPS is used as a time stamp source for lightning detection and location, so in aggregate with other detectors it can pinpoint a strike to within a meter or so anywhere in my hemisphere.
What misled you to think this? Radio altimeters are used throughout the aviation industry. Their ubiquity and criticality is the issue at hand. [0]
[0] https://www.faa.gov/other_visit/aviation_industry/airline_op...
First, there are situations where it's hard to get "awesome LTE" because there's a lot of usage. Getting more bandwidth is important to handle situations like that.
Beyond that, we don't know what the future will offer if we build greater capacity. When Apple launched the iPhone, we didn't know that we'd be changing the way we live our lives. Things like TikTok wouldn't exist without the abundant bandwidth offered by LTE. We don't always know what greater bandwidth and capacity will offer.
We are seeing some things already. We're seeing wireless home internet become available to a lot of people. For cell carriers, this is a new stream of revenue. For customers, this can be increase home broadband competition and for many rural customers the first chance at broadband.
We're seeing things like Nvidia's GeForce NOW allow you to play games that are being run on the cloud rather than your local device. Lower latency and greater bandwidth/capacity means a better experience. Nvidia recommends 50Mbps which LTE can do, but won't have as much capacity to support as many simultaneous users. 5G will also drive down latencies which are important for gaming.
It's possible that self-driving technology might take advantage of this in the future. I'm not someone that promotes self-driving tech, but one can see how lower latency and higher bandwidth/capacity could mean being able to send more data to the cloud both for computation and also for storage/learning.
A lot of people are talking about VR and meta-verses. Again, I'm not necessarily buying into this yet, but it seems like greater bandwidth and lower latency could make things better.
Heck, even video-conferencing on mobile can benefit from more bandwidth and lower latency. While LTE can accommodate it, there are times when networks get congested and less congestion is a good thing. Lower latency also offers a better experience.
Do you need it? No. But you don't need a smartphone. At the same time, it's possible that someone will create something that you won't know how you lived without that's made possible by more bandwidth/capacity and lower latency.
3G(HSPA) to 4G(LTE) was huge. I happily upgraded.
I think it's easy to forget that LTE wasn't as big a jump initially as we see today. Back in 2012, T-Mobile's HSPA network scored 5.5Mbps in PC World's testing against 7.4Mbps for Verizon's LTE and 9.1Mbps for AT&T's LTE. In PCMag's 2013 testing, T-Mobile's HSPA got a similar 7.7Mbps while the 4 LTE networks got 5.1Mbps, 10.3Mbps, 13.1Mbps, and 16.0Mbps. Again, LTE networks were seeing marginal improvements. Over time as network deployments matured and new LTE releases came out, LTE's improvements went way beyond HSPA.
But the first round of LTE phones on Verizon were terrible - way worse than any 5G device we saw. Some people wanted to be a first adopter. I think waiting a generation or two gives you better results, but some people always want to be first.
I actually think the reason the US pushed LTE so quickly is simply because Verizon didn't have an upgrade path for their 3G network which was stuck in the 1Mbps range while HSPA-based competitors were pushing into the 4-8Mbps range. In Europe, carriers could delay a year and offer dual-channel HSPA service in the meantime.
LTE was still better even in the early days, but the fact that CDMA didn't have an upgrade path put Verizon in a tough place. They could either watch AT&T offer 5x faster speeds than their HSPA network (at a time when AT&T had an exclusive on the iPhone) or they could be an LTE early adopter. I think AT&T would have liked to milk their HSPA investment a bit longer (as many carriers did around the world), but once Verizon started marketing LTE they had to follow.
And you're saying that the upgrade was huge - and it certainly has been. However, it was more marginal at the start. That's not to say it wasn't a good upgrade even initially, but it wasn't anywhere near the 40-50Mbps that LTE averages today in the US. If 5G can follow a similar trajectory, we'll be able to support a lot of things we can't today.
The point of 5G is better quality of service. Marketing people of course dumb down the improvements to "it's faster" but throughput is actually the least important thing. Though of course a better QoS means that operators can guarantee a bit better throughput as well.
Better latency, improved scaling for operators (more connected devices in an area), lower power usage, and more reliable connections. That is a big issue for me with 4G. Coverage here in Germany is not great and even in areas that are covered, the quality of service is pretty bad and I often struggle to get it to work at all even in places that are supposedly well covered. E.g. the are around the TV tower in Berlin (i.e. the largest FFing antenna in the wider area) is pretty bad because the area is full of tourists usually and the local base station ins hopelessly oversubscribed.
That's the kind of stuff you could reasonably expect to improve with 5G.
True but isn't wifi already lower latency and greater bandwidth? What things can we do on wifi that we can't on mobile data?
So a solution in search of a problem, then?
Bandwidth usage globally has been growing at around 30% per year for a long time now with nothing showing it would slow down (obviously not all of this is wireless). LTE will sooner or later run out of bandwidth and thus 5G basically allowing more mpbs on the same radio spectrum (and also rolling in new frequencies)
Even today in relatively low population density country like Finland (where I live) LTE connections in cities are slower during peak hours due to the radio frequencies just being full. (In general most plans have unlimited data so people use them a lot)
The long overdue update came and went. There just isn't the pressure built up for the next one.
I get the idea of incremental capacity and quality updates. But it's drudge work. What business models are people contemplating that has them so horny for 5g?
And this is valuable? If you dig a big hole in a public space people will fill it with garbage before long.
Technology should be driven by need. Building bigger pipes, bigger roads and bigger holes is just asking for more garbage to fill it with. Let's start with problems that are worth solving.
Was it ok? Sure, you can stream video just fine (my mobile isp didn’t force 480p video). But for anything behind basic browsing and consuming content it was a pain for example playing multiplayer games.
I was very happy when I moved back to a fixed line connection. So yeah, I would have been very happy with more bandwidth, lower ping and a more stable connection.
Just out of curiosity I tested my 4g speeds/ping - I got 30mbps and an average of 35ms (6.4ms jitter) here in the Netherlands (KPN network). Given by test results I certainly think you could have had a better network.
So sure, "excellent 4g" will do a good job, but you still need to expand into the C bands to make that happen.
If OP was talking about 4g vs. 5g with everything else equal including frequencies, then it's not necessary but 5g is somewhat better with basically no downsides.
But even with a good 4G connection, I think 10ms is better than 35ms and I think 300Mbps is better than 35Mbps. I think our current 4G networks work well, but higher speed and lower latency will improve the experience even for our current use cases and even when a person has a good 4G connection already.
Yes, lower frequency networks offer better coverage. It's why we see sub-1GHz 5G deployments from the 3 US carriers. These networks are offering marginal improvements (say 30% at present, but probably more in the future). As 5G standalone (rather than anchored to LTE) becomes common, they'll also offer significantly lower latency.
A lot of of 5G deployments are likely to be from 2-4GHz which is higher than most 4G deployments. However, in a lot of cities carriers are already splitting cells to get more capacity so the higher frequency doesn't matter as much as you might worry. Carriers are also working on 5G carrier aggregation which will extend 2-4GHz coverage a lot farther by allowing lower frequency signals to handle the uplink. Towers can put out more power to push their signals farther so the limitation is usually the uplink. If that's getting handled by lower frequency signals, it will effectively extend the range of 2-4GHz networks.
Yes, 5G is better. It's definitely not fully realized right now with a lot of carriers putting out very basic 5G networks partly for marketing purposes. However, 5G offers better spectral efficiency and it does offer opportunities to extend the range of higher frequency signals via carrier aggregation.
When I tested 5G, I got 1Xms (forgot exactly what, but lets say twice as less - maybe more). Anyway, latency was noticeably better (at least for RDP session). So that is single best improvement for 5G. Download speed was 320Mbit wired, 250Mbit wifi, but only 20Mbit upload - not so great.
Ofcourse it all depends on ISP, configuration, etc. When I first got modem, upload showed 10Mbit, complained to ISP, then it was 20Mbit, but depending on time of day 16-20mbit.
Anyway I don't understand the reasoning "why do we need...?". With that reasoning why bother going past 100Mbit ethernet? Oh, nice we got 1Gbit, so enough. I mean we may not saturate the channel, but it is nice for ISP to have the capability + some nice capabilities when we need that bandwidth (some huge transfer or whatever). + Streaming is data hungry, you may have multiple streamers at home.
The range of 4G depends a lot on which band you pick, but these C-band frequencies should go several miles, maybe half as far on average.
Does it deserve all the hype? It doesn't really seem like it. But cell infrastructure is definitely used well beyond phones, so I'm trying to keep an open mind.
Also 4G made decent YouTube streaming possible. It worked on 3G but was horrible. Now people can't do without it. We won't even know what 5G will bring us until it does.
2G: Slow WAP internet browsing 3G: Better internet browsing, maps, basic audio 4G: Stream video and better audio
5G:??
All the above were known beforehand because allowed for current apps which were on broadband to be used out of the house. I would be more convinced there would be everyday application if there was current technology that is on broadband that I can take remotely.
I actually think that there are a couple of solid examples of this:
* Console/PC videogames: people wanna play God of War on their bus ride, as evidenced by the massive success of the Switch and the growing excitement for the Steam Deck
* High-quality video calling: latency and bandwidth increases in 5G are both huge for the experience of FaceTime/Skype/Discord/etc.
* VR/AR: again, applications that are seriously harmed by both latency and bandwidth, and ones that have many concrete, business-value use cases in a mobile / non-living-room setting.
and my "dark horse" candidate:
* Machine learning applications: any "AI"-powered product or service has a quality that is pretty directly proportional to the amount of iterations it can perform. Self-driving cars have the capacity to gather gigabytes per second of environmental data; the ability to stream this data back to a central e.g. Tesla datacenter, rather than just doing procession onboard, confers a pretty serious increase to model quality.
I think a "local" network-free source of computing is unavoidable, and once it is available, I just don't see the point of setting up a complicated (and error-prone) infrastructure to make computations remotely when it is available and fall back on-the-fly when not. Given the amount of regulation this kind of things have to comply to, and how error-proof they must be, I wouldn't think anybody would be happy with this cascade approach...
Basically the cell companies outbid the homeowners for control of the last 100 feet between the house and the nearest utility pole. Now the auction losers will proceed to get screwed.
5G will help alleviate the strain on LTE networks in the long run, so I want (and have) it for that purpose.
I’m sure 5G will help, but unless I’m missing something I would suppose LTE could provide far better access in UK cities today.
When a friend moved to London for six months, a 4G modem & router was the cheapest option, (not least because rolling 1month SIM plans are common here, but ISPs like twelve months, and charge exit fees or a premium for a shorter plan), faster than the cheapest ISP plans, and delivered next day vs. two weeks' wait for an 'engineer' to visit and mess about with 'master sockets' and 'lines'.
I highly doubt it. There's only so much capacity per base station, so the amount of base stations needed would be prohibitive in urban settings.
I honestly don't think this is a serious plan even by cell companies, except in rural settings. That isn't to say that they won't dupe some number of urban dwellers into it, too. Enough to earn some money, not enough to overload capacity.
I can't speak for their seriousness obviously, but EE (major provider in the UK) is advertising wait-list sign-up/'coming soon' in London.
I recall tube ads years ago (it was probably 4G, but certainly not 5) for a minor player that sprung up using someone else's network (Three/EE/O2/Vodafone, I don't know) specifically to provide home internet. I think they got killed by uncapped/high cap data becoming more common, tethering being more allowed; so anyone who cared could use any provider (and any modem) directly - and most people don't care they just want it to work at a good price and be easy.
I think EE will make it an opt-in up-sell for now, but that eventually they (and others) will just send SIMs & modems out instead of 'engineers'. No more copper lines to faff about with. If the customer wants a landline number, well that's just adding minutes on to their SIM plan. (And for a while they'll get away with charging through the nose for that, like the old £15pcm line rental or whatever, until the masses realise that any SIM would work, and most high/unlimited data ones have lots of if not unlimited minutes included anyway.)
This was previously the dream with 4G/WiMAX, but ultimately they weren't able to have enough bandwidth per tower to make it reasonable. 5G has much better efficiency enabling way more clients per tower and far more throughput.
And its definitely a serious plan by cell companies. Several companies are already selling this. Obviously, they're not exactly planning every home, but enough to actually market it as a real service.
https://www.t-mobile.com/isp https://www.verizon.com/5g/home/
But yeah, I don't doubt that they'll try to lure a good amount of people in. Enough to make some free money, not enough to have to actually invest more in the network. Kinda like how ISPs (at least in Europe) were heavily pushing ISDN onto people as we stood before the dawn of DSL.
I doubt it'll be a large proportion of urban users though. I must admit I lived for a year on this kind of service, but this was because the town I lived in had some strange some strange local government monopoly on ISPs, and the monopolist delivered service that was barely usable (not hyperbole). The mobile providers circumvented this by "not being ISPs", and while what they offered was as terrible as everyone else in this thread has related, it beat out the even more terrible monopolist cable offer. I switched to fiber as soon as the monopoly was lifted.
1) In the US, its stupid expensive and difficult to be yet another provider laying cables to people's homes. When it comes to coax and fiber, there aren't local exchange carriers in residential areas; the company who laid the cable is the only one able to offer services on that cable. For another ISP to come in to compete at all, there's a massive amount of red tape and cost to lay essentially redundant cabling. Launching a new wireline ISP is stupid expensive and there's a lack of viable competition in many markets.
2) Cell companies have spent years splitting cells and making smaller and smaller cells in suburban areas. They've been building small towers all over the place and just about every water tower and office building these days has tons of antennas on it. So there's plenty of places to stick new equipment in suburban areas.
3) 5G is both a more efficient protocol and also a lot of new spectrum. So they can continue to use the low-band frequencies they're using for 3G/4G service for mobile users while then offering new services on the newer bands. Since they already have lots of places to stick antennas with fiber already laid, this is overall pretty cheap to more than double the capacity per tower. In reality, its far more than double, probably several times as much bandwidth per tower as the newer frequencies can help split the same tower into smaller sectors per tower.
4) A lot of those new bands are pretty much trash for mobile users in suburban settings. Low on the ground, in a car, deep inside a home, you're not going to get much service. However, if you put a small antenna near a window facing the tower, you'll get excellent service.
So to recap, there's a good bit of room for more competition in home internet services. There's already lots of places which are already set up to hang antennas with plenty of backhaul connectivity, so adding a ton of capacity per existing cell isn't terribly expensive for the carriers. 5G allows for more bands with far more bandwidth available overall. A lot of the new bands are trash for mobile users in many spaces, but are very practical for fixed wireless. This means fixed wireless 5G could become very competitive with wireline services in suburban and rural residential internet markets.
I was under the impression 5G is pretty worthless outside densely populated areas
Other comments mention fixed wireless which is also big (home internet access)
One challenge in rural broadband deployments is there are only so many good locations for the carrier to actually stick antennas. Maybe a water tower or two, you might get lucky and have some tall radio tower at the edge of town. So then all the customers in the area are essentially sharing a single tower, all needing to point their CPE to that one point. You can only slice the tower up into some number of sectors and once you hit that point the tower is saturated. Every additional customer is now diminishing the service for every other customer.
Having better spectral efficiency per sector means you can service more customers, have better service per customer, or even both depending on how you balance it.
You can already pretty much get what you want by going the other way. Get a fast home internet connection, use WiFi at home and at work and get the cheapest available pay per use data plan for the small percentage of data you use while in a car etc. Doesn't work for people who use a large amount of data while traveling, but that's not actually most people.
The idea is that you’re going to pay one cell phone bill for all of your devices if you want to get them online. I don’t know anyone stupid enough to pay for a SIM card for their personal iPad currently, because you’d prefer to tether off your phone instead of paying $10 a month. But in the future you might see people drop their home internet and just go with SIM cards in everything.
I mean, maybe, but more likely to just be a 5G modem with wifi/ethernet, like has been available with LTE. I've got one with a $5/month plan as backup for my DSL, because my DSL is unreliable, and the local cable company doesn't service my house, and municipal fiber installation is unsubsidized and the actual installtion costs are too high, IMHO.
https://ecfsapi.fcc.gov/file/12070826325320/AVSI%20AFE76s2%2...
https://ecfsapi.fcc.gov/file/12070826325320/AVSI%20AFE76s2%2...
https://ecfsapi.fcc.gov/file/1207722514473/AVSI%20AFE76s2%20...
https://ecfsapi.fcc.gov/file/1207722514473/AVSI%20AFE76s2%20...
https://ecfsapi.fcc.gov/file/12072133610936/AVSI%20AFE76s2%2...
https://ecfsapi.fcc.gov/file/12072133610936/AVSI%20AFE76s2%2...
https://ecfsapi.fcc.gov/file/1207848621283/AVSI%20AFE76s2%20...
https://ecfsapi.fcc.gov/file/1207848621283/AVSI%20AFE76s2%20...
https://ecfsapi.fcc.gov/file/12221132030652/AVSI%20AFE76s2%2...
https://ecfsapi.fcc.gov/file/12221132030652/AVSI%20AFE76s2%2...
It's quite interesting to me that the FAA may end up grounding planes rather than carriers delaying a rollout of 5G. This seems to say a lot about society and government priorities in the US.
(personally I don't know enough to make an informed value judgement here, but as a technology worker I'm biased toward preferring more and better internet at the cost of harming other sectors)
With FAA not being able to block the rollout, the only way of fulfilling their mandate is to ground planes.
Whenever I complain about how outdated and ineffective the FCC is, the literal pushback I get is "but what about airplanes and satellites". To which I say, touche', we should all do our part to make sure we have safe airports and open channels for satellites and astronomy.
Reading through a Link posted by @supernova87a (https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-In...) I have two take-aways:
1. The spectrum involved is valued in excess of $4.6bb
2. Most 5G deployments will create in excess of 100x (20dBm) the allowable interference for radar altimeters
From the report, page 18 (SC-239 study results):
HUGE AMOUNT OF SCENARIOS INVOLVED
Every base station configuration produces harmful interference both from 5G fundamental emissions in the 3.7–3.98 GHz band and 5G spurious emissions* in the 4.2–4.4 GHz band, across virtually all operational scenarios and relative geometries between the aircraft and base station.
5G user equipment (mobile phones) that may be operating onboard aircraft were also found to exceed the safe interference limits for Usage Categories 2 and 3.
I find it increasingly difficult not to be cynical about the role of the FCC with respect to public safety issues with a lapse like this.
If I shipped a product into the US that had a radar altimeter interference profile like this, I'd be fined and sued into the ground a hundred times over, and I'd accept that fine and outrage because I personally couldn't live with being responsible for any planes literally falling out of the sky because they thought the ground was in the wrong place on account of my product's interference.
But apparently, with enough lobbyists and money, it's an acceptable risk. It's hard for me to take the rest of the FCC's rules seriously, when they act as just another rent-collecting agency at the beck and call of lobbyists whose sole mandate is to create market barriers against small startups and imported goods, with little regard to actual safety, science, or modern technology...
edit - formatting
The basic problem here is that way too many radar altimeters are fundamentally defective in terms of being sensitive to emissions they should have been designed from the beginning to ignore.
The FCC doesn't make any promises that listening to the wrong frequencies won't produce harmful interference. That is the receiver's job to avoid listening to signals on those frequencies.
And if somehow radar altimeters can't or couldn't be designed to ignore radio emissions outside their assigned frequency range, the FAA should have demanded a far larger frequency band from the beginning instead of implying the one that was assigned was adequate for the purpose and then later attempting to squat all over frequency bands they were never assigned.
Furthermore, things could be much worse because the filters that are used to prevent leakage into radar altimeter frequencies can fail on a 5G device, but the 5G device would continue to operate just fine without anyone noticing (except for the plane that ended up in pieces on the runway).
In other words, 5G transmitters would normally emit sidebands that jam altimeters, if not for a handful of components that prevent it from happening. But if one of these components were to fail -- say, a user dropped their phone and one of the filter elements cracked or de-tuned -- it'd just straight up jam an airplane's altimeter.
I'd like to think that regulatory bodies exist because they are supposed to consider public safety as part of their mandate. We don't want to lose our children in an airplane crash and have the best answer be "whelp, that radar designed 20 years ago should have anticipated 5G jamming. Therefore that altimeter was defective. Anyways, no actual laws were broken, so those lives lost is just the price of progress".
I think an alternative view would be that the FCC should have spectrum auctions not just "because valuable things should go to the highest bidder", but in part to raise funds to upgrade things like airplane radars so they could tolerate the interference caused by the new equipment that was going to be installed in an adjacent band. Government does this all the time: you want to move your business into the neighborhood? You have to upgrade the infrastructure to support the burdens of your new business. We didn't run megawatt-scale power lines to every suburban block just in case someone wants to setup a datacenter there, and if the power goes out because of the datacenter's loads we don't blame the residents of the town for not having anticipated the Internet.
And with over $80 billion raised in spectrum auctions, you'd think that'd be within the realm of possibility - one could replace 100,000 radar altimeters at $10k a pop for "just" a billion dollars, or about 1% of the auction proceeds.
I think the US wants to be a 5G leader and it sees delays as potentially sacrificing that leadership. This might not be a real concern, but people complain anytime the US isn't the #1 in something and blame everything from politicians to capitalism. At the same time, it seems reasonable to believe that companies that have access to new 5G capabilities (speed, capacity, latency) will be able to develop and gain marketshare in new services. If American companies are going to develop the next generation of NewThings, playing around with the capabilities and limits of 5G networks in the real world will be an important part of that.
We've seen different countries with different scenarios. European countries that have nearly twice the guard band; countries that are mandating down-tilts; countries that have strict power limits; countries that don't have as strict power limits and are comfortable with the risk.
Personally, I don't understand why we didn't go with a phased approach. Set low power levels and a downward-tilt mandate. Ease the restrictions month by month and measure the real-world interference. Sure, maybe it means that C-Band networks aren't quite as good as they could be for 6 months, but I think predictable goals and timelines based on real-world data would satisfy cell carriers (who at least state they're confident that there will be no issue).
> 5G user equipment (mobile phones) that may be operating onboard aircraft were also found to exceed the safe interference limits for Usage Categories 2 and 3.
In some ways, this is what I'm more worried about. People have a smug sense that their phone can't interfere with planes and that regulations around cell phone use on planes are just BS. While the FAA/FCC will be able to enforce restrictions on cell carriers, it's going to be impossible to enforce it on users in-flight. You can't effectively make sure that devices are in airplane mode. Flight attendants can't see the indicator on my device (or lack thereof) when quickly walking up and down the aisles.
If C-Band causes interference with radio altimeters, I can see the FAA and FCC adding exclusion areas around airports, mandating antenna down-tilts and lower power levels in certain areas, and other mitigations. I think it's reasonably easy to get AT&T and Verizon to implement those and reasonably easy to check compliance. They might fight it, but it's still reasonably easy.
I think if C-Band phones cause interference, it's going to be a problem since we simply won't be able to police everyone on planes.
Problem is that some new popular designs are composite shells...
So the two uses appear quite far apart in the frequency domain. Do signals get sent out on the wrong frequency or something? What does it mean to interfere? And, assuming something bad is happening, why?
With potentially high gains from beamforming, both the fundamental mode and spurious emissions from 5G radios exceed the safe interference limits for the current RA specifications by at least 10 dB.
Radio towers (sites) have widely varying quality control of their tenant's installations. Other transmitters can mix and amplify signals from other carriers without well designed and maintained RF filtering on each and every antenna. The more transmitters at a site the more carrier frequencies that can contribute to the mixing, and the more opportunities for poor or broken RF filters. At some busy sites there is almost nothing you can do to prevent this. Anything on the tower that acts like a diode can cause mixing, even without being amplified by another transmitter.
This usually just harms other receivers at the site however. But an airplane flying close by could theoretically be affected depending on how close it is.
N.B. as far as I know, the portion of the C-band that's in question was allocated for satellite downlinks; uplinks were over 6GHz. With that in mind, there is indeed a Big Difference between a satellite in orbit radiating downwards, and a 5G beam forming installation on the ground potentially radiating upwards.
- The FCC, which is the government agency that has ultimate control over permitting what goes on in the nation's airwaves, proposed to make additional frequencies available for mobile phone use in 2018: https://www.fcc.gov/document/37-42-ghz-public-notice-opening...
- This was going to be done by "repacking" satellite communications in the C-band (3.7 GHz to 4.2 GHz) freeing up spectrum to be used by cell carriers.
- Boeing encouraged this in late 2018, mentioning that the FCC should give a 100MHz "guard band" to prevent interference with radar altimeters, which operate in the 4.2-4.4 GHz range: https://ecfsapi.fcc.gov/file/121184623679/Boeing%20C-band%20...
- The FCC implemented a 220MHz "guard band" based on studies with radar altimeters, leaving more than double the guard Boeing requested. This was based on studies to evaluate any interference using this frequency (https://arstechnica.com/tech-policy/2021/11/faa-forced-delay... is a good summary, there is a lot to read here).
- The FCC auctioned these 280MHz of airwaves (3.7 - 3.98 GHz) last year in FCC Auction 107, garnering $81,168,677,645 in gross winning bids. As there is a delay for the incumbent spectrum users to clear their usage, ATT and Verizon were only granted the use of a combined 120MHz of spectrum in limited areas, spanning the 3.7GHz to 3.82GHz range.
- Verizon and AT&T, the largest winners, have sought to deploy the spectrum they paid for in concert with the FCC rules. Specifically, this is the "lower" part of the overall winnings, which leave a minimum of ~400MHz between the top end of the broadcast frequency and the bottom end of altimeter operation.
- Airline carriers and the FAA came in at the 11th hour and asked the carriers and the FCC to halt their deployment, asking for more time to be able to study whether this was safe. After a lot of back and forth, Verizon and AT&T have agreed to some power reductions around airports and runways, and voluntarily delayed the rollout of broadcasting on these frequencies twice - most recently at the beginning of the year.
- The FAA has so far cleared the altimeters in ~45% of the commercial fleet: https://www.cnbc.com/2022/01/17/us-faa-clears-45percent-of-c...
Where we are now is a bit of a battle of regulators, airlines, and the cell operators that spent a significant amount of money on spectrum and capital expenditure (radios, antennas, etc) to deploy that spectrum.
The FCC has cleared the use of the airwaves, but the FAA insists that not all altimeters can avoid being interfered with, and are now issuing requirements that may ban the use of these instruments in cases where they otherwise would have been necessary. This may result in landings that may not be able to happen, causing diversions, etc.
The carriers and the FCC insist that over 40 countries are using this spectrum (which appears to be true) with various restrictions. In Japan, for example, there is a significantly smaller guard band of 100MHz, though the transmit power level is much lower than it will be in the USA. The carriers have voluntarily agreed to adopting restrictions around airports that roughly mirror that of France.
At this point, it's unclear what happens next. I am sure I am missing a lot here (why are altimeters sensitive to broadcasts happening 400MHz away from them? are they?), and there seem to be valid concerns and issues on both sides. Ultimately, this is largely looks like embarrassing game of cat/mouse between the FCC, FAA, cell carriers and airlines.
Apparently though there exist radio altimeters with basically no filtering at all, which worked properly in practice, since sat downlinks had nowhere near the power level needed to interfere. But now we are adding more powerful transmission closer to the altimeter band than was used previously, and altimeters designed without using meaningful amounts of filtering would be affected.
That claim that 400MHz of guard band (as this initial rollout still provides) might be insufficient for some altimeters is really something. Ideally the FAA can determine which ones they are, and deem them no longer airworthy.
I'm also wondering if in fact it is just that the standards for altimeters are far looser than what all altimeters actually implement. The FAA concerns seem to be based on the signals potentially interfering with an altimeter built to just barely meet the testing specifications, but they might all actually greatly outperform those specifications.
Any answers?
Edit: The link is a pdf.
https://www.faa.gov/sites/faa.gov/files/2022-01/50%20Airport...
Airline and manufacturing execs and the FAA/FTC are not risking their lives every day (although it might be eye opening if they would be willing to all cram into a plane and land in a thunderstorm at an airport with 5G towers at the end of the runway).
You've probably seen the videos where the system will do an audio countdown "100, 50, 40, 30, 20, 10, retard, retard" [Airbus].
That system is critically important in zero-vis triple-autopilot landings. You don't want cell phones screwing that phase up.
Now, single digit khz filters at RF frequencies, that's difficult. But not 200Mhz!
I guess the radio altimeter manufacturers just figured, "there's a large guard band, why play it safe and put in filters", or what?
If you are ham these bandwidth needs are just nuts.
And this has been 10 years in the making. The FCC must just be rolling their eyes - why didn't FAA do something earlier.
We have coverage during landing phase with a localizer and glideslope as well, plus RNAV / WAAS enhanced GPS options etc etc + the mark 1 eyeball. Somehow in the last year the US has just become helpless to solve problems. Hard to beleive folks flew across the ocean with no GPS or moving map etc etc.
also, and this is just my opinion, but the absence of plane crashes does not mean it's safe! some faulty things exist for years before anything happens and/or the issue is noticed.
It sounds kind of hysterical, sort of like programmers worrying about cosmic rays. Is this something that's deeply improbable and insignificant, or is it something that is guaranteed to happen eventually even though it is unlikely?
No. If you have an instrument operating at 4.3GHz and it suffers interference from radios operating at 3.9GHz, it indicates inadequate filtering. That's a design issue, not an event with a statistical chance of happening no matter what.
- downside of delaying 5g is slightly longer download speeds (?)
- downside of interference is planes might crash (!)
why not just give the FAA all the time it wants
For the same reason we allow multiple private companies in multiple countries to pollute the skies with (eventually) millions of satellites:
Sacred, holy, internet. Without which all human civilization could crumble to dust and blow away.
It only affects landing in bad weather.
Passsengers should also be sure to look up all the latest airworthiness directives and advisory circulars for the plane and engine type they're going to fly as well. And get the crew medical reports just to be sure.
Hell, maybe passengers should just as well check that the aircraft manufacturers haven't modified any critical safety systems that the FAA should've been regulating.
https://www.engadget.com/us-airlines-warning-letter-21191993...
Which spectrum are you referring to that carriers have purchased and not deployed, if not 3.7–3.9 GHz?