FAA ADs re 5G interference [Archive]

WillowRun 6-3

10th Dec 2021, 23:52

WillowRun 6-3,
Apart from marking a major blow-up between US Federal government agencies and thereby providing a potentially entertaining “pass the popcorn” opportunity for those of us outside the USA, does this escalation in inter-agency hostilities have any collateral benefits for US airlines?
For example, can an airline now sue the FCC because it will be able to demonstrate an actual loss (e.g. “We can no longer schedule flights to XXX after dark or in bad weather”) whereas before they could only point out a potential detriment?

I'd like to say I anticipated this question - though I didn't. So I'll start at the end, and work back toward the start.

For an airline to file a lawsuit against the FCC, among the issues I'd want to hammer down is, to what extent is it realistic to anticipate that a federal district court (presumably where suit would be filed) would even have the competence to deal with the technical issues? While it is true that federal district courts do see litigation involving arcane and complex subject matters, these are subjects which get presented to the courts with some frequency, and do not present new technology just now entering service. (It's not perfect as a comparison, but consider what a hash Congress has made with regard to establishing regulatory frameworks for social media.) And in complex arcane matters before federal courts at present, I think most veteran litigators - and especially their clients - would concur with the assessment that the results of those cases leave a lot to be desired. It's one thing to get the statute of limitations analysis, where equitable tolling arguments are made, correct - quite another to resolve dueling expert witnesses with regard to proper statistical techniques for assessing results of Phase III clinical trial of a prostate cancer pharma product. So I would question whether the court, in perhaps a novel turn of a standard phrase, is a court of competent jurisdiction.

Of course an airline might go ahead and sue as part of a political effort by airlines. Or for some notion of public relations points. On the other hand, what actual claims could be made -- abuse of discretion under the Chevron deference-to-agency interpretation of statutory provisions? - I don't know. I mean, I don't know the answer already, plus I'm not planning on drilling into it (uh, absent an actual client, that is), plus there's more to respond to in your question.

So this is a "blow-up" between federal agencies?, "escalating inter-agency hostilities"? Well, it's really not. Because as you know the FAA is "housed" within the Department of Transportation, which is headed by a political appointee. The current Secretary's background for his appointment and confirmation by the Senate - apart from some slick presidential primary campaigning which of course is utterly meaningless - is that he was Mayor of a small city the apparatus of which is dominated by a major private university (Notre Dame). So in refusing to let cellular providers take control, the FAA has stepped into the breach. And it was able to do so, in major part, precisely because the Department in which FAA is situated is headed by a Secretary who really does not have much knowledge whatsoever about, you know, how things work (and don't work) up front, that so-called pointy end of the airplane. Just my view, not an official or verifiable opinion, of course.

But your post did more, for it reminded your loyal forum SLF/atty of how much I enjoyed popcorn during some several months when I held a volunteer gig (sort of) at Chicago O'Hare. And to return the favor, and since the first real blow-up was, of course, in 1966 and directed by Michelangelo Antonioni and produced by Carlo Ponti - for your enjoyment of a non-U.S.A. film to accompany that popcorn:
Blow-Up (imdb.com) (https://www.imdb.com/video/vi772194585?playlistId=tt0060176&ref_=tt_pr_ov_vi)

mnttech

13th Dec 2021, 00:40

As noted in the IFALPA paper (to be read until the end), there is the SAIB and there are two ADs (one for aircraft and one for helicopters): 2021-23-12 and 2021-23-13.
.
oops...Missed that until I got into the office and saw the ADs.
Anyhow, the drive behind the AD is a simple change to the flight manual IF there is a NOTAM out on the problem.....
My guess is the number of NFF removals of RA's is going to go through the roof, or worse, real problems are going to be signed off as 5G issues. What a mess

EEngr

13th Dec 2021, 01:58

does this escalation in inter-agency hostilities have any collateral benefits for US airlines?

There might be downsides. I don't know who sits closer to the president in his cabinet meetings or state dinners. But if the FAA perceives itself to be the possible loser in an administration d:mad:k-swinging contest, they might not appreciate getting dragged into this fight.

fdr

13th Dec 2021, 02:06

Amazing state of affairs.

LRRA are pretty much essential equipment for approaches below CAT I minima. So, yeah, that's a bit of a nuisance. At least the weather in the USA, like JFK, IAD, ORD never goes bad, It's all like California, or Queensland, beautiful one day perfect the next. Same for CDG, LHR, EDDF etc in the EU. Great.

I seem to recall once we were told how GPWS works, a mandated system... so, presumably the GPWS escape manoeuvers that ensue from the erroneous ramp-up of LRRAs will be enjoyed by one and all. Going to be most entertaining in a stack as someone gets a false GPWS "pull up" and bobbles through the pack above.

Will the FAA send out a revision to this lunacy with an edict to disconnect the LRRA input to de-activate GPWS systems? that would be something that would look bad on your resume after the first pax plane plants itself in the sod with a crippled GPWS system. EGPWS is faaaantastic, but GPWS is still mandated by the FARs, but perhaps it now gets partial retirement by EGPWS... except that multiple modes of GPWS are not provided by EGPWS... hmmm. Maybe it is just software, just like the change from 7.0 to 7.1 which was just software at about $100,000 per box, after all it's not like Honeywell to miss a chance to fleece the industry.

At least GPS is a fine basis for all safety systems, except, in the last 18 months around the SCS region, where the dispute over 9 line vs every other nation in the world seems to curiously result in jamming by persons unknown of GPS signals, taking out independent certified GPS systems of different design, OEM, op software. That is a bit untidy for EGPWS systems. Remarkably, there are some systems that are not certified that continue to work reliably and also give EGPWS guidance. Neat that the certified system gets jammed and messed by unknown jammers with disregard for civil aviation, yet the uncertified systems work like a charm.

Glad to see that the FCC and FAA had everyone's backs on this one.

GlobalNav

13th Dec 2021, 03:33

There might be downsides. I don't know who sits closer to the president in his cabinet meetings or state dinners. But if the FAA perceives itself to be the possible loser in an administration d:mad:k-swinging contest, they might not appreciate getting dragged into this fight.

I think it’s “who sits closer to the moneyed interests”, which might be the same, I don’t know.

fdr

13th Dec 2021, 04:05

Suggest all Ops Managers, and all flight crew that have a desire to have GPWS send their seasons greetings to:

Brett Portwood, Continued Operational Safety Technical Advisor, COS Program Management Section, Operational Safety Branch, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 817-222-5390; email: operationalsafety at the good ol' FAA dot GOV.

At this time, the constraints are to remove SA CAT I/II/III, Autoland, EVS and the like at the NOTAMed airports, but your GPWS system is also compromised, so expect warnings to go off. Just what you want is a warning system that goes off randomly, it results in a resistance to response that may affect real warnings. The insanity of this nonsense is breathtaking, the only realistic defence is to have VMC operations only below safety height, which should pretty much stop all turbine traffic in the east of the USA that may be subject to this NOTAM in the season of cheer... or risk repetitive false warnings resulting in resistance to response in real cases, that's what humans do. We are good at learning workarounds, and those workarounds tend to become pavlovian heuristics that have unintended consequences. Of course, Collins, Honeywell and co, can always come up with new LRRAs that operate on a new band, that shouldn't take more than 5 years to push through, and about 25K per aircraft, 3 times that for Boings and Airbusses etc...

Wish that the FAA and FCC had kept with just making a stew to go with yoghurt and tabbouleh instead of becoming amorous with the goats.

FAA 2021-23-12 DOCKET (https://www.federalregister.gov/documents/2021/12/09/2021-26777/airworthiness-directives-transport-and-commuter-category-airplanes#open-comment)

:}

At least IATA and IFALPA understands the issue, even if it was subsequently disregarded in the FAA AD...

IATA PROBLEM STATEMENT 27 NOV 20 MONTREAL (https://www.icao.int/safety/FSMP/MeetingDocs/FSMP%20WG11/IP/FSMP-WG11-IP08_ICAO%20Flight%20Operations%20Panel%20and%20IATA%20%20IF ALPA%205G%20problem%20statement.pdf)

List of potential equipment failures:

Interference to RA operations can affect:

1. Autoland functions: This is particularly critical in low visibility auto approach like Cat II or III conditions. Pilots cannot conduct CAT II and III approaches if RA is malfunctioning.

2. EICAS/ECAM: Nuisance warning after take-off or during approach which will distract crew from their tasks at hand. This will lead to deterioration of operational safety levels.

3. False or missing GPWS alert: Anywhere in proximity to ground, this could inhibit some functionalities of the TAWS (Terrain Alerting Warning System) reactive modes which would remove a safety net in case against CFIT (Controlled Flight Into Terrain). Additional distractions for crews from tasks at hand, – “too low gear” and “too low flaps”, “don’t sink”,” terrain and pull up warning” and other alerts. A big concern is GPWS not triggering an alert when it should have done so, because of interference which can result in CFIT event!

4. Unreliable instrument Indications: This could contribute to an increased number of hard landings because of errors in automatic altitude indications and voice announcements.

5. Abnormal behaviours in Automatic Flight Systems: a. Autoland system b. Flight Control Laws (e.g. failure to transition to Flare law resulting in a higher than expected pitch on the flare; Retard function, etc.) c. Auto-throttle automatic stall protection. d. Auto Speedbrake deployment

Remember, your busses, big 'n little, use RA for determining control laws.... watch this space...

In spite of the perceptiveness of IATA and IFALPA in NOV 2020, we get 5G on the same band as the RA's???? WTF!

Klauss

13th Dec 2021, 05:29

Hi, would anyone know what the FAA action is based on ? Did they test actual equipment, i.e. radio altimeters near 5G antennas, or did they study the literature which says there is a possibility that there might be trouble ? I am hoping that tests have been conducted to get to the bottom of this ....

ex-Dispatcher

13th Dec 2021, 08:15

I'm a PNT technologist not a pilot and only comment (occasionally) on technical matters. I used (a very long time ago) to be an FAA qualified Aircraft dispatcher, There was a US PNT Advisory Board (PNTAB) meeting in Washington last week at which Hon. Jeff Shane, IATA Representative & PNTAB Member gave a presentation on recent FCC decisions and implications. I can't post a link but the presentation is here and quite informative... perhaps someone else could post/share for me. The presentation is available to download on the gps.gov website under the PNT Advisory Board Dec 9-10. , Dec 09 5.15-5.40pm.5th Meeting
December 9-10, 2021

pba_target

13th Dec 2021, 08:55

WillowRun 6-3

13th Dec 2021, 21:31

To add perhaps some significance to one of the above posts, Jeff Shane is General Counsel of IATA - in the realms of public and private international air law, positions for attorneys working as lawyers don't get any more significant than that. (Correction: Mr. Shane retired as GC summer 2020 - but still.)

Here's the link to the agenda for the PNTAB meeting recently, in case it might be of interest.
GPS.gov: 25th Meeting of the National Space-Based Positioning, Navigation, and Timing Advisory Board - December 2021 (https://www.gps.gov/governance/advisory/meetings/2021-12/)

(Also, in my previous post, I was somewhat tentative in arguing that the FAA had stepped into what it saw as a kind of power vacuum. It appeared that the cellular providers had been able to out-lobby, out-money, and out-influence the voices of and advocates for integrity of the aviation safety ecosystem. And that with the start of this White House administration, its Secretary of Transportation - lacking as he does any operational experience or insight with regard to aviation operations or safety, or big-league interest infighting in Washington (despite his other fine qualities) - had emerged as a . . . . bystander. So rather than cede the playing field to the cellular providers, and knowing that the current DoT leader isn't a heavy-hitter like Liddy Dole or Elaine Chao, FAA took the bull by the horns. I think, with the explanation of just how bad the risks to operational aviation safety really are (THANK you fdr and others), this power-match map looks even more accurately drawn.)

With U.S. Permanent Rep to ICAO Council, Ambassador Chesley "Sully" Sullenberger having now been sworn in to his office, maybe something different can take shape. Hope springs eternal.

wokawoka

13th Dec 2021, 21:45

A bigger issue ,as far as I can see, is that even in perfect weather any, sustained disturbance in the RA signal on the Airbus could cause a downgrade in the control laws. Definitely not something you want at the bottom of an approach in a windy day.........

Sallyann1234

14th Dec 2021, 10:36

In spite of the perceptiveness of IATA and IFALPA in NOV 2020, we get 5G on the same band as the RA's???? WTF!

Just to be clear, they are not in the same band. They are in adjacent allocations, with a small guard band in between.

For interference to be avoided, two conditions need to be met. 1) the 5G equipment must not radiate significantly outside its allocated band, 2) the airborne equipment must must not be significantly sensitive to transmissions outside its allocated band. And of course the same conditions apply in reverse.

It is the task of frequency administrations to specify operating limits accordingly - and this must be done on an international basis.

hoistop

14th Dec 2021, 13:55

Sallyann1234

14th Dec 2021, 16:01

So, if a Telecom needs to put 5G tower under approach path, they are free to do it, and FAA will merely tell everybody that from the date of installation, CAT I / II / III is effectively not available at this airport anymore. I always thought that such action (interfering with A/C navigation equipment) is something that terrorists would do, but now this is perfectly legal ??!! :( :yuk: :eek: World going insane.
The national radio regulator can impose whatever conditions it sees fit on the cellular operator's licenced operations in order to protect other services. So it could in theory say that there will be no 5G operation with x km of every airport.
Naturally the operators will resist this strongly as it would create holes in their service coverage (and airports are major concentrations of mobile radio use.)
I'm not party to internal US affairs but this would seem to be an issue between FCC and FAA, each being subject to different political pressures.

But again this is an international issue and other countries may treat it differently, within the International Radio Regulations to which each country subscribes.

nnc0

14th Dec 2021, 17:42

.......... it could in theory say that there will be no 5G operation with x km of every airport.

That's what Canada has done.

Klauss

14th Dec 2021, 20:00

That's what Canada has done.

Hi, that´s cool...but does it help the helicopters that are flying low everywhere ?
Don´t know.

nnc0

15th Dec 2021, 00:05

Hi, that´s cool...but does it help the helicopters that are flying low everywhere ?
Don´t know.

a national antenna down-tilt requirement to protect aircraft used in low altitude military operations, search and rescue operations and medical evacuations all over the country

Canadian Source document is here

Decision on Amendments to SRSP-520, Technical Requirement for Fixed and/or Mobile Systems, Including Flexible Use Broadband Systems, in the Band 3450-3650 MHz - Spectrum management and telecommunications (https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf11747.html)

cattletruck

15th Dec 2021, 09:12

a national antenna down-tilt requirement to protect aircraft used in low altitude military operations, search and rescue operations and medical evacuations all over the country

That's interesting considering the 5G signal is beam forming (with a couple of lobes near the antenna). Perhaps they mean "software" down-tilt but I don't know if the 5G tech is that far developed. Theoretically it should be possible to fix this issue in software for antennae located near airports as it's all just crazy mathematics anyway.

As someone who has worked with the greedy mobile telecoms, I can assure you they will fight tooth and nail to maintain their market advantage, but they also understand liability too well so I am pretty sure this whole issue was unforeseen by them as it takes years and much expense to get their wares out to market, and now the bureaucrats have been left to sort it out the only way they know how.

Imagegear

15th Dec 2021, 11:26

Perception:

So the guy in seat 1A decides to text the cab company on his new 5G phone while on finals to 27R.
The potential for this scenario must be much higher and though the transmission is at a lower power, close proximity to the goon show up front should have resulted in a more terminal arrival.
Are instances of equipment degradation more than is reported?

IG

Sallyann1234

15th Dec 2021, 11:55

The classic cellular base/tower has antennas with a downtilt to limit the interference potential to other cells. However this will not always be the case depending on local topography.

As for the guy in 1A, his phone will not be using the new frequency band if it cannot receive a signal in that band. It may still be using 5G on a lower frequency band, but the interference potential is due to the frequency of the transmission, not the modulation method. 3G or 4G could also cause interference if on the 'wrong' frequency. Also bear in mind that the GPWS antenna is pointing downwards, so relatively immune to signals from inside the plane.

Imagegear

15th Dec 2021, 14:18

Thanks,

I should be relieved but somehow I think the thought will cross my mind at the wrong time - :eek:

wrench1

15th Dec 2021, 19:14

Hi, that´s cool...but does it help the helicopters that are flying low everywhere ? Don´t know.
In the US, no. There appears to be more issues with the rotorcraft side given a number of approved helicopter approaches operate in prime 5G territory and especially in the GOM. With plans to expand 5G service to over 50,000+ square miles of the GOM this could negate most of the OSAPs used for deepwater ops as they require an operative radar altimeter. And given the only place to put 5G towers is on the same platforms the helicopters operate it will definitely cause some issues. Time will tell.

Klauss

15th Dec 2021, 19:55

In the US, no. There appears to be more issues with the rotorcraft side given a number of approved helicopter approaches operate in prime 5G territory and especially in the GOM. With plans to expand 5G service to over 50,000+ square miles of the GOM this could negate most of the OSAPs used for deepwater ops as they require an operative radar altimeter. And given the only place to put 5G towers is on the same platforms the helicopters operate it will definitely cause some issues. Time will tell.

Hm.... so, what about testing ? Aviation Week shows pictures of test-chambers for satellites and military antennas. Is it possible that a bit of time in such chambers could be booked to see what happens with real equipment ? Not good to do the testing in the wild outdoors....the city-canyons and so forth.

wrench1

15th Dec 2021, 21:27

Hm.... so, what about testing ? Aviation Week shows pictures of test-chambers for satellites and military antennas. Is it possible that a bit of time in such chambers could be booked to see what happens with real equipment ? Not good to do the testing in the wild outdoors....the city-canyons and so forth.
FYI: this issue didn't simply arise when the ADs were released. The 5G/radar altimeter issue has been under scrutiny for some time now so there are a number of studies out there. Here's one presentation released last year. Time will tell which direction it will take but the implications will be global especially on the heavy plank-wing side. But from what I see there is currently no cheap/easy aircraft operational solution at hand for this issue at least on this side of the pond.
https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-Interference-Risk-to-Radar-Altimeters.pdf

Klauss

16th Dec 2021, 05:19

FYI: this issue didn't simply arise when the ADs were released. The 5G/radar altimeter issue has been under scrutiny for some time now so there are a number of studies out there. Here's one presentation released last year. Time will tell which direction it will take but the implications will be global especially on the heavy plank-wing side. But from what I see there is currently no cheap/easy aircraft operational solution at hand for this issue at least on this side of the pond.
https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-Interference-Risk-to-Radar-Altimeters.pdf

Great presentation. I live in Europe, and things are a bit different here. Found this compact explanation on the web: https://bit.ly/3m916uq So, our EASA is a bit more relaxed than the FAA. However, I think they shouldn´t be. Euro-Airlines are flying to the US, on occasion :eek: and the telecoms industry here isn´t going to stand still in their efforts to get products to market.

Sallyann1234

16th Dec 2021, 12:15

davidjpowell

18th Dec 2021, 19:24

From informal contacts with the UK regulator OFCOM, it seems their present attitude is not to panic but to keep a close watching brief on the situation.

The four UK cellular operators are busy building up their 5G networks, but as far as I can see none of them are yet operating in the 3.5 GHz band around e.g. LHR or LGW. This could of course change at any time as they compete to gain value from their licence investments.

OFCOM have also been consulting on possible new uses within the 3800 - 4200 MHz band which is primarily used for satellite services. This of course is immediately adjacent to the air radar band.

I'm not sure I would say busy. The four UK networks have been struggling to roll out 5G - UK wants to be a market leader, but government meddling has broken the UK market. It is impossible to say whether the lack of 5G midband is due to airports, because they have not got there yet, or simply in the too hard to tick box. Some of the in-airport coverage is also delivered in a very bespoke way, which I suspect will take time to sort out.

Sallyann1234

21st Dec 2021, 11:41

BBC report todayBoeing and Airbus warn US over 5G safety concernshttps://www.bbc.co.uk/news/business-59737194

WillowRun 6-3

22nd Dec 2021, 19:52

Airlines for America and two other major trade associations have announced that they're trying to resolve the 5G service introduction issues (Aerospace Industries Ass'n and Cellular Telecommunications Industry Ass'n).

link to announcement:
Statement from A4A, AIA and CTIA – Airlines For America (https://www.airlines.org/news-update/statement-from-a4a-aia-and-ctia/)

"WASHINGTON, DECEMBER 22, 2021 – The following statement was issued today by A4A, AIA and CTIA:
We are pleased that after productive discussions we will be working together to share the available data from all parties to identify the specific areas of concern for aviation. The best technical experts from across both industries will be working collectively to identify a path forward, in coordination with the FAA and FCC.

Our belief is that by working collaboratively in good faith on a data-driven solution, we can achieve our shared goal of deploying 5G while preserving aviation safety."

Klauss

23rd Dec 2021, 07:22

Hi, I found this: https://www.iliad.fr/en/actualites/article/free-mobile-participe--une-opration-de-drisquage-124
In French, dated 3/09/2021 : https://www.universfreebox.com/article/497531/free-decolle-pour-une-operation-derisquage-de-la-5g

Looks like the French did at least a bit of testing. Don´t have more details, but the movie makes a good impression that makes me ask for more of the same, maybe different helicopter, different 5G installation, and, of course, fixed wing aircraft.

Sallyann1234

23rd Dec 2021, 08:54

Unfortunately that test - or at least the report of it - is of no use without a mention of the frequencies that were used for the 5G transmissions. Were they in the new band 3.6 to 3.8GHz* which is of concern due to being nearer to the aeronautical allocation, or in the lower cellular bands e.g. 2.6GHz?

It is the potential conflict from nearly adjacent frequencies that is critical. 5G cellular in the lower bands, which has been in use for some time, poses no risk to airborne operations.

* individual national allocations may be different.

Klauss

23rd Dec 2021, 12:01

Hi,
sorry, I have absolutely no more details......and google couldn´t find any further reference to the trial.
There should be a report out on it by the French Authorities, i´d say.... no idea, though, where to look for it.
K

Unfortunately that test - or at least the report of it - is of no use without a mention of the frequencies that were used for the 5G transmissions. Were they in the new band 3.6 to 3.8GHz* which is of concern due to being nearer to the aeronautical allocation, or in the lower cellular bands e.g. 2.6GHz?

It is the potential conflict from nearly adjacent frequencies that is critical. 5G cellular in the lower bands, which has been in use for some time, poses no risk to airborne operations.

* individual national allocations may be different.

Imagegear

23rd Dec 2021, 17:17

There is a large area of 5G at 3.5 Ghz around the town of Pamiers in the region of Cazaux in South West France. (The area identified in the Video posted above.)

5G at 3.5Ghz in France (https://mobile.free.fr/couverture/index.html)

Selecting the 5G button on the page will present both 700mhz (In Green) and 3.5gb (In Blue) just noting that it could be either that was used in the test.

Also the spectrogram display on the monitoring system in the helicopter was indicating 3.64 to 3.675 Ghz. I can only assume to be a range around 3.65 Ghz.

IG

SeenItAll

23rd Dec 2021, 19:05

Just to be clear, they are not in the same band. They are in adjacent allocations, with a small guard band in between.
.

The guard band provided by the FCC is not small. It is huge -- over 200 MHz.

YRP

23rd Dec 2021, 19:30

The guard band provided by the FCC is not small. It is huge -- over 200 MHz.

200 MHz is not large, percentage wise.

Current technology allows building filters like that without too much difficulty. But when the radars were designed, it would have been quite challenging.

I suspect the radars were at the limits of contemporary technology at the time — which is why they used that frequency band, since nothing else but satellite stuff could use anything nearby.

As a result, it appears the existing radars are more susceptible to out of band interference than is now desirable.

Sallyann1234

23rd Dec 2021, 22:30

The guard band provided by the FCC is not small. It is huge -- over 200 MHz.

The gap is wider - from 3800 - 4200 MHz in Europe. In the UK, the regulator Ofcom is looking at allowing other services into this band in addtion to existing fixed links and satellite services.

WillowRun 6-3

24th Dec 2021, 12:34

Flight Standards Service of FAA has issued SAFO - Safety Alert For Operators - 21007, 23 December 2021. Subject and Purpose sections quoted verbatim:
"Subject: Risk of Potential Adverse Effects on Radio Altimeters when Operating in the Presence of 5G C-Band Interference.
Purpose: This SAFO provides information and guidance to operators regarding the risk of potential adverse effects on radio altimeters when operating in the presence of 5G C-Band wireless broadband signals, and the role of Notice to Air Missions (NOTAMs) in identifying the geographic areas where certain operations requiring a radio altimeter are prohibited in the presence of 5G signals (in the C-Band) by Airworthiness Directives (ADs) 2021-23-12 and 2021-23-13."

Link to FAA website and the SAFO document:
SAFO21007, Risk of Potential Adverse Effects on Radio Altimeters when Operating in the Presence of 5G C-Band Interference (faa.gov) (https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2021/SAFO21007.pdf)

FAA also issued an SAIB - Special Airworthiness Information Bulletin, AIR-21-18R1, "Risk of Potential Adverse Effects on Radio Altimeters"
Here is, verbatim, its opening paragraph:
"This Special Airworthiness Information Bulletin (SAIB) informs aircraft manufacturers, radio altimeter manufacturers, operators, and pilots of the planned deployment of wireless broadband networks in the 3700-3980 MHz bands (C-Band).1 C-Band wireless broadband deployment is permitted to occur in phases with the opportunity for operations in the lower 100 megahertz of the band (3.7-3.8 GHz) in 46 markets beginning as soon as December 5, 2021; however, the FAA does not expect actual deployment to commence until January 5, 2022. This SAIB recommends that radio altimeter manufacturers, aircraft manufacturers, and operators voluntarily provide to federal authorities specific information related to altimeter design and functionality, specifics on deployment and usage of radio altimeters in aircraft, and that they test and assess their equipment in conjunction with federal authorities. Results from that testing and assessment should be reported to the appropriate civil aviation authorities (CAAs) and spectrum regulators. The FAA is currently collaborating with the Federal Communications Commission (FCC) and the National Telecommunications and Information Administration (NTIA) to assess the need for mitigation beyond the recommended action in this SAIB." (emphasis added)

Link to FAA website and SAIB:
AIR-21-18R1.pdf (faa.gov) (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/dc7bd4f27e5f107486257221005f069d/379cfb187d16db10862587b4005b26fc/%24FILE/AIR-21-18R1.pdf)

(This SLF/att'y credits FlightGlobal Daily Briefing (24 Dec. 2021) for noting this development.)

Klauss

26th Dec 2021, 04:52

Thanks for posting.
I find the list of potentially affected systems in the SAFO to be an eye-opener.
A spurious radio-altimeter indication and nuisance (?=!?!) TERRAIN callout might be one thing, could be handled by procedures/airmanship,
but a malfunctioning tail strike prevention system ? No idea what that can do in aircraft such as a 777 or 747-8.
Pilots can´t influece such systems, can they ? Least of all during flare/takeoff, when they are needed.
Maybe a simple ´airport closed due to 5G interference´ NOTAM text might be best.
K

Sallyann1234

26th Dec 2021, 09:07

From WillowRun's links it's clear that the FCC is well aware of the potential problem, since they are restricting the initial C band cellular to below 3.8 GHz. This allows a clear 400 MHz gap from the air radar band, the same as in Europe.

But this restricts the US cellular band to only 100MHz width, which is unlikely to satisfy their requirement long-term, particularly in cities. In Europe the cellular band starts lower at 3.6 GHz, giving a full 200MHz bandwidth.

As the document states, much more needs to be known about the radar equipment sensitivity to out-of-band signals, but it does seem there is no need for immediate safety concerns.

edit: changed an M to G

turbidus

29th Dec 2021, 13:20

What was scary about the SAFO as it contained sample NOTAM's....Autoland, HUD, SA CAT I / II, CAT II, III, or RNP AR...all NA due to 5G?!?!?!

ZHU AIRSPACE RDO ALTIMETER UNREL WI AN AREA DEFINED AS XXXNM RADIUS OF XXXXXXNXXXXXXXW (VOR/DME) SFC-5000FT AGL. HEL OPS REQUIRING RDO ALTIMETER DATA FOR OFFSHORE INSTRUMENT OPS, HOVER AUTOPILOT MODES, SAR AUTOPILOT MODES, AND CAT A/B/PERFORMANCE CLASS TKOF AND LDG NOT AUTHORIZED EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C-BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVE 2021-23-13

BDL IAP BRADLEY INTL, WINDSOR LOCKS, CT. ILS RWY 06 (SA CAT I AND SA CAT II), AMDT 13A… ILS RWY 06 (CAT II AND CAT III), AMDT 38A… RNAV (RNP) Z RWY 06, AMDT 1… RNAV (RNP) Z RWY 24, AMDT 1… PROCEDURE NOT AUTHORIZED EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G CBAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVE 2021-23-12

SPECIAL COOK CANYON RANCH, RANGER, TX. RNAV (GPS) RWY 17, ORIG...RDO ALTIMETER UNREL. AUTOLAND, HUD TO TOUCHDOWN, ENHANCED FLT VISION SYSTEMS TO TOUCHDOWN NOT AUTHORIZED EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C-BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVE 2021-23-12

WillowRun 6-3

1st Jan 2022, 18:52

By letter dated 31 December 2021, the Secretary of Transportation and FAA Administrator have documented an interim plan and solution to the 5G interference issues. The letter is on Secretary Buttigieg's letterhead though it bears the signatures of both senior officials (something a lawyer would pause to note, but anyway) - here is the link to the FAA website and the letter:

DOT and FAA Letter to ATT and Verizon executives on 5G (https://www.faa.gov/sites/faa.gov/files/2021-12/12.31.2021%20-%20DOT%20and%20FAA%20Letter%20to%20ATT%20and%20Verizon%20.pd f)

For those possibly too uninterested or unconcerned to read it closely, the basic point of this development is to push back the start date for 5G service by these two companies by two weeks, to continue what evidently has been a constructive dialogue between FAA (and DOT to the extent the 'mother-ship' federal agency is involved at levels above FAA proper) and the two service providers (ATT and Verizon). Also, the letter outlines a way of segmenting the problem, so that some areas around certain airports would not see 5G introduction until more is known about potential interference modalities and solutions. There also is a role being pitched for AMOCs, Alternative Means of Compliance. It's just two pages, give it a read.

Not least, in the eyes of this SLF/attorney, there is nice language at the end about the predominant significance and critical importance of aviation safety in the United States. "Aviation nation" - kinda has a nice cadence to it, I think I could self-load to it.

boaclhryul

2nd Jan 2022, 21:01

Politico: "AT&T, Verizon reject Buttigieg's plea to delay 5G launch amid warnings of aviation chaos" https://www.politico.com/news/2022/01/02/at-t-verizon-5g-launch-aviation-526365

WillowRun 6-3

2nd Jan 2022, 22:26

Politico article contains a link to the letter dated 2 January 2022 replying to the Dec. 31, 2021 letter from Buttigieg and Dickson. Even reading it for speed over accuracy, it's pretty evident that ATT and Verizon had their reply teed up and quite ready to be dispatched.
This volley in the exchange is both longer and more detailed than the government's letter a few days ago.

https://www.politico.com/f/?id=0000017e-1c36-dee4-a5ff-fe3e997f0000

WillowRun 6-3

3rd Jan 2022, 00:09

More items for those interested in the play-by-play level of developments, as the date of January 5 looms large.
The U.S. airline trade association, Airlines For America, filed an emergency petition with the FCC seeking to delay the start of 5G service. (It's a full-blown legal document, although as is typically the case, reading the first few pages or sections would provide a good overview and most (if not nearly all) of the main points being argued.)
Link is from an FCC filings website:

Emergency Petition for Stay -- Final.pdf (fcc.gov) (https://ecfsapi.fcc.gov/file/123022756098/Emergency%20Petition%20for%20Stay%20--%20Final.pdf)

Also, on Twitter, a very knowledgeable person has posted a couple of threads examining some of the technical issues (way over this SLF/atty's level of antenna and electromagnetic spectrum knowledge). @Satcom_Guru
One thread examines the 2020 RTCA report on these issues, which (if I'm getting the message correctly) the wireless carriers say has been debunked and discredited, while the airlines are continuing to rely upon it.

Perhaps most significant considering the source, the U.S. Representative who holds the chair of the Committee on Transportation and Infrastructure of the House of Representatives, Hon. Peter DeFazio (of Oregon) has issued this statement (from Committee website):

"In light of the fast-approaching deadline for deployment, Airlines for America has taken the prudent step of filing an emergency petition to stay 5G deployment. I support their efforts and urge both the aviation and telecom industries to continue working together to find a safe way to deploy 5G technologies. For years—and as recently as this fall-- I have urged the FCC to put aviation safety first and thoroughly examine all risks involved. We can’t afford to experiment with aviation safety. I’ll continue to work with the federal government and the aviation community to make sure we’re not putting corporate profits above the safety of our skies."
_________________

This is going to end up in a courtroom, one would forecast without great concern for overstatement.

Edit: After reading a good portion of A4A's Emergency Petition for Stay . . . well, bad call on my part, in response to kiwi grey's question way up-thread. That question was whether U.S. airlines might benefit from suing FCC. What I had not realized, or thought enough about to anticipate, is that there already has been extensive agency proceedings before FCC in this matter. The initial Report and Order granting licenses for 5G in the C-Band, followed by petition(s) for reconsideration, and other filings, extensive in scope and amount. The "aviation community" has presented extensive evidence to FCC - evidence which A4A's current Petition argues the FCC has inexplicably ignored (and unlawfully ignored).

So my earlier (flippant, perhaps) comments were wrong, because I took the question as addressing a lawsuit from scratch. That was, actually, very wrong. Also, the politics around this matter are a bit trickier than at first impression. Despite strong objections during the first portion of the agency proceedings (that is, before FCC), the auction of spectrum took place in early December 2020 - during the transition between White House administrations. Draw your own conclusions about whether or not cooler heads did prevail, or even could have prevailed, during that time period.
So, to go back to kiwi grey's inquiry.

Well, reading the A4A Emergency Petition - and KUDOS to the lawyers for anytime you see a brief with some catchable typos, you know the time-pressure they were under was killer, killer - I would say that the FCC is going to get a very severe thrashing in federal district court. Well worth the price of popcorn - and I'm buying, kiwi grey, because after further review, indisputable legal reasoning shows I made the wrong call. Cheers!

Klauss

3rd Jan 2022, 03:34

Klauss

3rd Jan 2022, 03:35

Apologies, forgot a link: https://www.speedtest.net/ookla-5g-map

Sallyann1234

3rd Jan 2022, 08:57

Thank you very much WillowRun and others for your postings - very interesting reading.
Just...why is this 5th of January such an important date ?
The popular OOKLA internet speed testing site shows lots and lots of commercially available 5G stations around the world, and also close to airports, like JFK.
So, the 5G horse is out of the stable - or is it ??
K
To clarify the issue once again, there is nothing magic about 5G transmissions that threatens aviation.

5G cellular been operating safely for a couple of years or more in many countries, as shown in the map you linked. Virtually all 5G cellular currently operates in existing frequency bands. I'm using 5G to post this message, on a 2.6 GHz band network.

The potential problem is that cellular systems are now being licensed in a new frequency band between 3.6 and 4.0 GHz - the so-called C band. The exact frequencies vary according to individual country regulations. It is this frequency band which is at issue, and any modulation method in this band whether 2G 3G 4G 5G might possibly be a problem for aircraft radars that respond in this band.

Can we please not conflate 5G with C band. This only confuses the issue, as you have demonstrated.

cattletruck

3rd Jan 2022, 10:32

From https://en.wikipedia.org/wiki/5G_NR_frequency_bands

C-Band frequencies are defined as n77, n78 and n79. The problem band is n77 which is quite a broad band, almost 1Ghz.

As I mentioned above, even though the mobile phone telecoms are brutally competitive with each other they have always centred their business around growth which also means not killing off their customers. I'm sure by their very competitive nature we will see them pursuing the FCC for any compensation they are entitled to.

Sallyann1234

3rd Jan 2022, 11:02

There is no suggestion that all of n77 will be used for cellular. That is very unlikely for the foreseeable future.
In Europe only the the n78 sub band is to be used, with an upper limit of 3.8 GHz.

The problem in the US is that FCC has defined an upper limit just below 4.0 GHz, much closer to the air radar band. However they seem to be restricting initial assignments to below 3.8 GHz , which is a sensible move.

Luc Lion

3rd Jan 2022, 14:29

The RTCA document quoted above (and hereafter) gives a good deal of contextual information and of explanation on how interferences can jeopardise radar altimeter operation.
However is does not give much numeric information and it is considered as discredited by some stakeholders.
https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-Interference-Risk-to-Radar-Altimeters.pdf

The following document from the ITU gives more numeric information and its publication date (02/2014) makes it more resistant to discredit.
https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.2059-0-201402-I!!PDF-E.pdf

I'd like to highlight 3 pieces of information contained therein :
- the ITU recommendation for RA filters (ITU-R SM.337) : 24 dB per octave (or 80 dB per decade) with a maximum of 40 dB ; this is a 4th order filter (or four stages filter).
I checked the "paper" specifications of 2 radar altimeters ; they comply with the 80 dB per decade recommendation.
- the front-end overload level of tested actual radio-altimeters that ranged from -30 dBm (at best) to -56 dBm (at worst).
It means that these altimeters are overloaded with interference when their cumulated power is above 1 microWatt (1 10^-6 W) for the best device or above 2.5 nanoWatt (2.5 10^-9 W) for the worst, that power being measured after reduction by the input filter. (note: 0 dBm = 1 milliWatt, thus -30 dBm = 10^-3 x 1 milliWatt = 1 microWatt)
- the in-band sensitivity to interference noise is only 6 dB below thermal noise (probably caused by the large width of the band)

Let's put these numbers in perspective:
A signal from a 5G base station, at the frequency of 3.8 GHz, will overload the altimeter with -30 dBm overload characteristics if the plane antenna receives it with a power exceeding 2.2 microWatt. (I ignore cable losses).
For the worse device with -56 dBm overload characteristics, only 0.0056 microWatt will suffice to overload it.

If the same computation is made with a signal at 3.98 GHz, the best device will be overloaded with a power of 1.54 microWatt and the worse with a signal of 0.0038 microWatt.
So, allowing the frequency to step from 3.8 GHz to 3.98 GHz has the same effect as allowing the emitted power to increase by a factor 1.45 or it can be balanced by reducing the emitted power by that ratio 1.45.
We also see that the quality of the high frequency operational amplifiers used within or after the 4 stages filter is playing a much more important role than the cut-off frequency of the 5G band ; the factor between the best and the worst device is 400 !

A typical 4G antenna emits a 40W signal which gives slightly under 1 mW/m2 (1 milliWatt) of radiated power at 100 meters (note: the signal is not emitted in all directions of the full 4pi solid angle).
If a 5G antenna emits with the same power, a signal at 3.8 GHz is 500 times too powerful for the -30dBm radio-altimeter placed at 100 meters and about 200,000 times too powerful for the other one.
However, at 2.5 kilometers, it becomes acceptable for the best device.

Apologies: the paragraph above is wrong : I mistakenly made calculations that assume a 1 square meter antenna for the radar altimeter. That's way too much. I found RA antennas with surfaces of 0.01 m2 and 0.025 m2. For calculation examples, I'll associate the larger antenna with the RA having an overload threshold of -30 dBm and the smaller one with the RA having -56 dBM,
If a 5G base station emits a 40W signal at 3.8 GHz that is received by a radar altimeter at 100 meters distance, the power transferred through the antenna is about 25 microWatt which is a bit more than 10 times too powerful for the first radar altimeter. Increasing the distance to 300 meters or more will reduce the signal below threshold. For the second altimeter, the power transiting through the antenna is around 2000 times too powerful. For that one, the distance needs to be increased to 5 km. So, the size of the antenna can explain a part of the overload characteristics, but not all of them.

Sallyann1234

3rd Jan 2022, 16:26

The transmitter power limits in Europe are given in this EU document:

relevant technical conditions applicable to the 3 400-3 800 MHz frequency band (https://docdb.cept.org/download/163)

I don't have a reference for the FCC power limits, but I expect this will be available somewhere.

Klauss

4th Jan 2022, 04:50

Thank you very much for the clarification, Sallyann1234.:ok:

QUOTE=Sallyann1234;11164417]To clarify the issue once again, there is nothing magic about 5G transmissions that threatens aviation.

5G cellular been operating safely for a couple of years or more in many countries, as shown in the map you linked. Virtually all 5G cellular currently operates in existing frequency bands. I'm using 5G to post this message, on a 2.6 GHz band network.

The potential problem is that cellular systems are now being licensed in a new frequency band between 3.6 and 4.0 GHz - the so-called C band. The exact frequencies vary according to individual country regulations. It is this frequency band which is at issue, and any modulation method in this band whether 2G 3G 4G 5G might possibly be a problem for aircraft radars that respond in this band.

Can we please not conflate 5G with C band. This only confuses the issue, as you have demonstrated.[/QUOTE]

Grummaniser

4th Jan 2022, 08:09

(note: 1 dBm = 1 milliWatt, thus -30 dBm = 10^-3 x 1 milliWatt = 1 microWatt)
-
I'm not going to argue with the rest of your maths as I am unqualified to do so but the 1mW reference is 0dBm, not 1dBm. (1 X 10^0)

Luc Lion

4th Jan 2022, 08:35

Thanks for the correction.
Sorry, it was hastily written.
The point I wanted to make was that there is quite probably ample room for balancing measures, like computing a safe distance between the base ground station and the path of the plane or like capping the total radiating power of the base station in the C band.

Also, a part of the problem is the lack of formal minimal specifications for radar altimeters.
If a minimal slope for the pass-band filter was defined (like the ITU recommendation of 24 dB per octave) and if a minimum overload level (in mW/m2 or in dBm/m2) was defined, it would be much simpler to specify the conditions of immunity from interferences caused by 5G ground stations.

Sallyann1234

4th Jan 2022, 08:42

Your calculations need to take full account of antenna beamwidths, which are important in link calculations.

The cellular antennas generally radiate in the horizontal plane or with a downward tilt, so when the aircraft is at its nearest, directly above, it will receive little signal. Conversely, when the aircraft is approaching the cell site and may if low enough be within its beam, the radar antenna is looking downwards and not at the cell site.

The worst calculated case of the two antennas looking directly at each other is extremely unlikely to happen.

Luc Lion

4th Jan 2022, 09:29

You are quite right for the cellular antennas radiating lobes.
However, the reception cone for radar altimeter antennas is quite large : between 35° and 60° of cone aperture for the 3dB (half power) cone.
Here is a datasheet example of such an antenna ; it announces a minimum of 45° in roll angle and 40° in pitch.
https://www.sensorantennas.com/wp-content/uploads/2015/01/S67-2002-121.pdf

So, basically, a plane which is turning final with a 25° bank angle at 2000 ft height is sensitive to radio beams coming from more than 1.7 km or 1 sm from the outer direction of the turn (2000 ft x tan(45°+25°)).
And if we accept a gain loss of 10dBi, it probably extends to several statute miles away.

Sallyann1234

4th Jan 2022, 09:50

That's an interesting link, thank you.

But taking your example, at 2,000 feet the signal from a cellular antenna, most likely with a downtilt at almost ground level a mile away, should be extremely small. It shouldn't be too difficult to engineer the cell sites accordingly.

Luc Lion

4th Jan 2022, 10:23

I agree with you : mitigation measures ARE possible

India Four Two

4th Jan 2022, 11:18

Another delay in US rollout:

https://www.bbc.com/news/business-59856063

Sallyann1234

4th Jan 2022, 14:30

This issue is not going to be resolved by letters back and forth, or by yet another short delay.
As discussed above this is not going to be resolved just by calculation. It needs practical tests.

How hard would it be for Verizon to set up a cell site on the approach to a USAF base, and have the FAA run some test flights? It should have happened months ago, and if it has where are the results?

RatherBeFlying

4th Jan 2022, 16:50

Previous discussion covers direct radiation from the cell tower to the RA antenna, but we are talking about C band which reflects from terrain, structures and conveyances.

Reflected radiation from a cell tower may also be received by the RA antenna. The potential signal strength needs to be assessed. Also different sites may produce different reflection patterns.

Klauss

5th Jan 2022, 05:00

Hi, I´d be all for this idea. The French helicopter tests ((somewhere up in this thread)) were a step in the right direction, but I couldn´t find a proper report on them.
Yes, a real world C-band 5G system at a known location, like a USAF base, and then have airplanes go by ....when it´s CAVOK, fine weather.

This issue is not going to be resolved by letters back and forth, or by yet another short delay.
As discussed above this is not going to be resolved just by calculation. It needs practical tests.

How hard would it be for Verizon to set up a cell site on the approach to a USAF base, and have the FAA run some test flights? It should have happened months ago, and if it has where are the results?

Luc Lion

5th Jan 2022, 13:08

The problem with a single serie of tests is that it will only be valid for the radar altimeter type installed in the testing aircraft, and for the same antenna fit.
The lack of radar altimeter specifications results in having different electronic characteristics for each altimeter type.

I believe that this issue will only be overcome if each altimeter maker provides the authorities with the results of standard tests on the interference immunity of their device : standard size and gain of the supported antennas, characteristics of their band filter, saturation curve of their first amplification stage vs frequency, supported in-band interference and noise level, etc.

Maninthebar

5th Jan 2022, 13:10

I believe that this issue will only be overcome if each altimeter maker provides the authorities with the results of standard tests on the interference immunity of their device : standard size and gain of the supported antennas, characteristics of their band filter, saturation curve of their first amplification stage vs frequency, supported in-band interference and noise level, etc.

Um, maybe I am naive (maybe??) but are these not data that manufacturers would have needed to supply in order to get their devices certified for installation in airframes?

Sallyann1234

5th Jan 2022, 13:51

The problem with a single serie of tests is that it will only be valid for the radar altimeter type installed in the testing aircraft, and for the same antenna fit.
The lack of radar altimeter specifications results in having different electronic characteristics for each altimeter type.

I believe the FAA have access to a variety of aircraft. Of course one type alone would not be sufficient.
But why is nothing practical apparently being done? Is everyone waiting for someone else to make a move?

WillowRun 6-3

5th Jan 2022, 23:38

Report in The Wall Street Journal for edition published Jan. 6 2022 (and on WSJ website presently) indicates that DOT and FAA negotiated a deal with the two wireless carriers based on a "term sheet" reportedly reviewed by WSJ. Would be interesting reading, most likely.

U.S. DOT and FAA have (per the article) agreed not to seek or demand further delays. In addition to the current two-week delay, the federal authorities accepted the limitations most recently proposed by ATT and Verizon.

Without seeing the "term sheet" (and having any technical information in it explained properly), it is a guess to say that some plans appear to have been outlined, at least, for engineering, testing or other technical steps toward validating lack of interference or extent of any potential interference that does exist or might exist.

The major passenger and cargo airline trade group, Airlines for America, reportedly has elected to hold short of filing in federal court (presumably motion papers for a TRO, Temporary Restraining Order - though it's an easy call that this thread has already overstayed any welcome that might have existed for lawyer-speak, let alone more details about that fascinating federal procedure topic, "How to Stay an Agency Order When a Reconsideration Petition Still Is Pending").

WillowRun 6-3

7th Jan 2022, 20:03

FAA has created a webpage devoted to "5G and Aviation Safety". Information posted at present includes FAA position that system operational characteristics in France are not the same as in the U.S., and that risks to flight safety identified (in various written pieces) by the "aviation community" will continue to be present, even with the mitigation steps recently agreed to.
Website also contains links to prior FAA statements and related documents.

5G and Aviation Safety | Federal Aviation Administration (faa.gov) (https://www.faa.gov/5g)

physicus

7th Jan 2022, 22:23

What's truly interesting about this is that incumbent services should enjoy protection from harmful interference from new services regardless of whether said interference is intentional or not. This is a first that a national spectrum management agency has thrown their hands in the air and allowed a new service to potentially disable a safety of life critical system.

Having said that, it is sadly also completely in line with the level of incompetence and disregard for established procedure we have seen over the past years at the FCC.

WillowRun 6-3

8th Jan 2022, 02:05

As has been widely reported since it was announced in late December (the 22nd), the three major trade associations most directly involved have supposedly begun an effort to "work collectively to identify a path forward." Those associations were, of course, Airlines for America (A4A), Aerospace Industries Association (AIA), and Cellular Telecommunications Industry Association (CTIA) (see post #38 above).

Well, a little further poking around on internet resources and a technical brief by CTIA showed up. It's lengthy and detailed, but I'm posting it here anyhow...... because the conflict or, at least, disagreement about the bona fides of the safety concerns cited by FAA is a quite sharp disagreement, or conflict.

An SLF/attorney isn't going to comment on the technical matters. But -- reading the CTIA technical brief, its treatment of the bona fides of safety factors on approaches and missed approaches..... wouldn't that be within somebody else's expertise? And isn't there a factor in aviation system safety thinking that insists upon getting all the right answers first, rather than relying on a legal and regulatory-agency process to find answers that are then taken as necessarily right? (Also, the tech brief refers to "Aviation" as if it is a monolithic, unified sector, which isn't the case.)

The CTIA technical brief:
210903-CTIA-Ex-Parte-5G-Aviation-Technical-Annex.pdf (https://api.ctia.org/wp-content/uploads/2021/09/210903-CTIA-Ex-Parte-5G-Aviation-Technical-Annex.pdf)

(Couple of days ago, Wall Street Journal posted an editorial scoring (I mean, commenting with heavy negativity) the Biden Administration's handling of this situation, and not excluding the Secretary of DOT or Administrator of FAA from this criticism. But for reasons WSJ doesn't have to explain, the editorial piece appeared just on the website, not in the print edition or its electronic iteration. Not dispositive of anything, but always fun to see "the business world" take on dueling heavyweight sectors of the economy.)

Klauss

8th Jan 2022, 07:35

Thank you for the CTIA assessment, WillowRun 6-3. It´s as described, as study that shows up possible faults at other studies....in great detail. Some , rather astonishing, and so even to one not fully familiar with dB and other radio-science things.

I fully support your question about the safety : ....And isn't there a factor in aviation system safety thinking that insists upon getting all the right answers first.....
That´s how it used to be. Airbus and Boeing bend airplane wings until they break, to be shure that the right answers were given by the computer models, even at 2.5 times design load, or so, for example.
That kind of thinking would lead to tests, real world test of real aircraft flying over and near 5G towers transmitting at higher than nominal power to confirm that everything was safe - with a couple of passenger phones working in the aircraft in normal mode, not airplane mode. Yes, the passenger devices should all be in a airplane - safe mode, but with 2-300 passengers and at least as many phones and what not...who believes in 100% correct switching ?

That beeing said, the thinking seems to have changed. safe until proven dangerous ....that´s the new mantra, it looks like. EASA has a Safety Info Bulletin here: https://ad.easa.europa.eu/ad/2021-16
In that, they write: -quote- At this stage, no risk of unsafe interference has been identified in Europe. -unqoute-

That´s comforting .... until you consider the wing-bending example above. In analogy, it might be that ´airplanes are safe as no case of a wing breaking has been observed´.....because they just didn´t encounter any turbulence yet.

Slightly strange change of thinking.

So, I´d really like to see some real-world tests to enshure that 5G , operated with US paramaters, including some faults in antennas + aircraft, is safe. Some towers have to be put up, switched on, and aircraft + helicopters need to fly .

K

As has been widely reported since it was announced in late December (the 22nd), the three major trade associations most directly involved have supposedly begun an effort to "work collectively to identify a path forward." Those associations were, of course, Airlines for America (A4A), Aerospace Industries Association (AIA), and Cellular Telecommunications Industry Association (CTIA) (see post #38 above).

Well, a little further poking around on internet resources and a technical brief by CTIA showed up. It's lengthy and detailed, but I'm posting it here anyhow...... because the conflict or, at least, disagreement about the bona fides of the safety concerns cited by FAA is a quite sharp disagreement, or conflict.

An SLF/attorney isn't going to comment on the technical matters. But -- reading the CTIA technical brief, its treatment of the bona fides of safety factors on approaches and missed approaches..... wouldn't that be within somebody else's expertise? And isn't there a factor in aviation system safety thinking that insists upon getting all the right answers first, rather than relying on a legal and regulatory-agency process to find answers that are then taken as necessarily right? (Also, the tech brief refers to "Aviation" as if it is a monolithic, unified sector, which isn't the case.)

The CTIA technical brief:
210903-CTIA-Ex-Parte-5G-Aviation-Technical-Annex.pdf (https://api.ctia.org/wp-content/uploads/2021/09/210903-CTIA-Ex-Parte-5G-Aviation-Technical-Annex.pdf)

(Couple of days ago, Wall Street Journal posted an editorial scoring (I mean, commenting with heavy negativity) the Biden Administration's handling of this situation, and not excluding the Secretary of DOT or Administrator of FAA from this criticism. But for reasons WSJ doesn't have to explain, the editorial piece appeared just on the website, not in the print edition or its electronic iteration. Not dispositive of anything, but always fun to see "the business world" take on dueling heavyweight sectors of the economy.)

Sallyann1234

8th Jan 2022, 09:10

I can't disagree with Klauss.

Allowing C Band cellular except near airports is fine for normal airline operations, but what happens when an airplane has a distress condition and is off course? It may be flying close to cell sites, perhaps on a hilltop where they are often sited, and be deprived of height information at the very time when it is most vital.

And how does this help with low level operations over urban areas with a high density of cellular activity?

This really does seem another case of "We'll try it and see if it works". And we all know where that has led to recently.

Klauss

10th Jan 2022, 08:15

hi,
I just realized that the FAA list of 50 airports that have some reduced-power 5G operations ((my wording)) is not complete.
For whatever reasons, airports like Atlanta and Denver aren´t in.
I think the networks will install normal, high-power 5G stations near those places- lots of people, lot´s of purchasing power...
AND: lots of airplanes will fly there. With normal radio-altimeters. Got to remember that they are on, non-switcheable, from the moment
aircraft power-up at the gate to parking and shutdown.
Consequently, high power 5G and altimters will operate close to each other at Atlanta and Denver.

It will be interesting to watch.

K
I can't disagree with Klauss.

Allowing C Band cellular except near airports is fine for normal airline operations, but what happens when an airplane has a distress condition and is off course? It may be flying close to cell sites, perhaps on a hilltop where they are often sited, and be deprived of height information at the very time when it is most vital.

And how does this help with low level operations over urban areas with a high density of cellular activity?

This really does seem another case of "We'll try it and see if it works". And we all know where that has led to recently.

FiveGirlKit

10th Jan 2022, 11:32

hi,
I just realized that the FAA list of 50 airports that have some reduced-power 5G operations ((my wording)) is not complete.
For whatever reasons, airports like Atlanta and Denver aren´t in.
I think the networks will install normal, high-power 5G stations near those places- lots of people, lot´s of purchasing power...
AND: lots of airplanes will fly there. With normal radio-altimeters. Got to remember that they are on, non-switcheable, from the moment
aircraft power-up at the gate to parking and shutdown.
Consequently, high power 5G and altimters will operate close to each other at Atlanta and Denver.

It will be interesting to watch.

K

Airports with 5G Buffers | Federal Aviation Administration (faa.gov) (https://www.faa.gov/newsroom/airports-5g-buffers)
The 50 Airports with 5G Buffer zones are considered safe, and so any airport not on the list is not considered safe?!? I wonder therefore the NOTAMs restricting operations will be limited to the non-listed airports...

WillowRun 6-3

10th Jan 2022, 15:57

Website of ALPA-International is running an information-intensive page on the 5G deployment situation:

5G C-Band, NOT Cleared for Takeoff - ALPA (https://www.alpa.org/advocacy/5g-interference)

Also, from Politico's Transportation newsletter, the following (quoted verbatim) about the posture of the major airports organization w.r.t. the situation:

AIRPORTS AREN’T HAPPY: The Airports Council International – North America on Friday called the FAA's analysis "irrelevant,” arguing that the ripple effects of the deployment will hit the entire national airspace hard, including flight cancellations and delays. Last week’s deal pushed the 5G expansion date to Jan. 19, and AT&T and Verizon agreed to employ additional protections at certain airport zones until July.

“Despite eleventh-hour efforts to resolve obvious concerns that could have been addressed months ago, this attempt at a short-term fix does not address a number of critical uncertainties about the potentially adverse impact of 5G on certain low visibility approaches,” ACI-NA President and CEO Kevin Burke said in a statement.” This so-called fix will create winners and losers within the airport community, and the entire aviation system will suffer under the terms of this deal.”

Sallyann1234

10th Jan 2022, 17:59

What kind of crazy excuse for a plan is this? It satisfies no-one.

The cellular side are concerned because they can't use C band at many airfields.
The aviation side are concerned because they don't have protection near many other airfields.

Are the unprotected airfields being used as an unwilling test case, with future regulations depending on whether there are many incidents at them over a period of time?

There are just too many variables of equipment, operation and terrain for such a plan to be adequate. A merely representative test based on a subset of conditions answers nothing. As observed above, aviation has never worked this way.

An issue on this scale, involving potential risks to life as well as billions of dollars, requires a properly organised test regime based on equipment specifications and actual worst-case physical operation.

Klauss

13th Jan 2022, 03:57

Hi,
found a bit of a test description from here in Europe. 1 test in Norway and France.
https://cept.org/Documents/ecc-pt1/67990/ecc-pt1-22-020_easa-eurocontrol-input-to-ecc-report-on-mfcn-ra-compatibility
unzipp, look at the larger document.

The tests don´t look like the more comprehensive version Sallyann1234 prefers.....but they are for the lower power, more freq. separation conditions here in Europe. So, maybe they are ok as a first try....
Looking forward to seeing the US version of real-world tests.
K

What kind of crazy excuse for a plan is this? It satisfies no-one.

The cellular side are concerned because they can't use C band at many airfields.
The aviation side are concerned because they don't have protection near many other airfields.

Are the unprotected airfields being used as an unwilling test case, with future regulations depending on whether there are many incidents at them over a period of time?

There are just too many variables of equipment, operation and terrain for such a plan to be adequate. A merely representative test based on a subset of conditions answers nothing. As observed above, aviation has never worked this way.

An issue on this scale, involving potential risks to life as well as billions of dollars, requires a properly organised test regime based on equipment specifications and actual worst-case physical operation.

FiveGirlKit

13th Jan 2022, 11:46

NOTAMs have been issued, effective on 19 January (when 5G is turned on). Example:

!FDC 2/3714 SFO IAP SAN FRANCISCO INTL, SAN FRANCISCO, CA. ILS RWY 28R (SA CAT I), AMDT 15A ... ILS RWY 28R (CAT II - III), AMDT 15A ... ILS RWY 28L (SA CAT II), AMDT 27B ... PROCEDURE NA EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C-BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVES 2021-23-12, 2021-23-13 2201190500-2401190501EST

Now the fun starts....

Klauss

13th Jan 2022, 18:04

Yes.... 1400 Notam....approximately. :confused:

NOTAMs have been issued, effective on 19 January (when 5G is turned on). Example:

!FDC 2/3714 SFO IAP SAN FRANCISCO INTL, SAN FRANCISCO, CA. ILS RWY 28R (SA CAT I), AMDT 15A ... ILS RWY 28R (CAT II - III), AMDT 15A ... ILS RWY 28L (SA CAT II), AMDT 27B ... PROCEDURE NA EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C-BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVES 2021-23-12, 2021-23-13 2201190500-2401190501EST

Now the fun starts....

WillowRun 6-3

13th Jan 2022, 22:42

"Maintaining Safe Operations with Radar Altimeter Interference from 5G" issued by IFALPA (based on ALPA-International).
Indexed as 22SAB01 superseding and updating prior bulletin on same topic (21SAB16)
Link (from IFALPA website):

22sab01-maintaining-safe-operations-with-radar-altimeter-interference-from-5g.pdf (ifalpa.org) (https://www.ifalpa.org/media/3723/22sab01-maintaining-safe-operations-with-radar-altimeter-interference-from-5g.pdf)

Sallyann1234

14th Jan 2022, 08:40

So now we know how tests are to be done. Every flight is to be a test, and every radar altimeter is to be considered unreliable near airports.
How does the pilot, perhaps under pressure from other adverse factors, decide whether the radalt reading and the systems connected to it are right or wrong?

Tango and Cash

15th Jan 2022, 00:39

Few Cloudy

15th Jan 2022, 06:58

How much of a problem is the signal from a mobile phone (or many mobile phones)? Is this a signal strength issue?

You can control where the fixed antennae are but not where mobiles are used. And they are certainly not angled downward.

Doesn’t a mobile send out a “squitter” from time to time to test network availability? On all possible bands?

And are there other items on these bands - stage wireless or sports equipment?

Sallyann1234

15th Jan 2022, 09:00

Big Pistons Forever

16th Jan 2022, 17:28

There is now reporting that G5 interference is particularly problematic for the B787. Apparently it uses RA data for air ground logic switching and interference may effect spoiler and reverser operation :uhoh:

WillowRun 6-3

16th Jan 2022, 23:00

U.S. FAA has issed CAN-2022-01-2, "Continued Airworthiness Notification to the International Community" dated Jan. 14, 2022.
Subject is 5G interference as it affects certain functions or operations of 787 aircraft, worldwide.

(Apologies, not accessing FAA link to post here - but it's quite e-z to locate)

Also, Satcom_guru has technical information in posts on the Tw soc media platform (which is how this SLF/atty learned about the referenced FAA CAN).

Big Pistons Forever

17th Jan 2022, 00:35

Sigh, another own goal for Boeing engineering…..

snowfalcon2

17th Jan 2022, 16:29

Progress:Collaborative Work Underway to Reduce Delay, Cancellation Risk
Approved radio altimeters will allow commercial aircraft to continue low-visibility landings in the 5G C-Band deployment areas.The agency has made progress during the last two weeks to safely reduce the risk of delays and cancellations as altimeter manufacturers evaluate data from the wireless companies to determine how robust each model is. This work has shown some altimeters are reliable and accurate in the 5G areas; others must be retrofitted or replaced.

Today, the FAA cleared an estimated 45 percent of the U.S. commercial fleet to perform low-visibility landings at many of the airports where 5G C-band will be deployed on Jan. 19.
The agency approved two radio altimeter models that are installed in a wide variety of Boeing and Airbus planes. This combination of aircraft and altimeter approval opens up runways at as many as 48 of the 88 airports most directly affected by 5G C-band interference.

The airplane models approved include some Boeing 737, 747, 757, 767, MD-10/-11 and Airbus A310, A319, A320, A321, A330 and A350 models. FAA expects to issue more approvals in the coming days.

See updates on https://www.faa.gov/5g

PAXboy

18th Jan 2022, 08:19

Perhaps a dumb question: The folks that allocate bandwidth for use - would they not have known all the devices likely to operate in a given band? Or, should they have known?

Nil by mouth

18th Jan 2022, 10:42

An update on the BBC web-site https://www.bbc.com/news/business-60036831

Klauss

18th Jan 2022, 11:03

...were enogh to find out some hard info on 5G and radioaltimeter compatibility.
Amazing.
So, how much do we know in 2 months ?
and....what about the year that went by.. ?

Shrug. As bystander, I can only wonder at what happens.

FullWings

18th Jan 2022, 12:33

It's extremely unlikely that handsets could cause a problem. They operate at much lower power than the base stations, and they respond at lower frequencies in the bottom part of the C band.
______

Let's be clear about what is happening here. There is a potential issue of interference to radar altimeters from C band cellular, which calculations suggest might happen. For technical reasons, the risk is likely to be greatest in the USA.

At the moment, both sides are walking around the issue by restricting operations and/or reducing reliance on equipment. For obvious reasons, these have to be temporary measures.

What seems to be missing at the moment is any move to test whether the interference would actually exist under normal operations, and to what extent.
I think that’s a reasonable summary. The other thing to add is that that FAA appear to be in full-defence bureaucrat mode having been caught with their pants down over the 737 Max, and there also seems to be a political infight between them and the FCC; toys are exiting prams all over the place and air transport is collateral right now...

Few Cloudy

18th Jan 2022, 19:30

DaveReidUK

18th Jan 2022, 19:45

U.S. FAA has issed CAN-2022-01-2, "Continued Airworthiness Notification to the International Community" dated Jan. 14, 2022.
Subject is 5G interference as it affects certain functions or operations of 787 aircraft, worldwide.

(Apologies, not accessing FAA link to post here - but it's quite e-z to locate)

Continued Airworthiness Notification to the International Community - Boeing 787 Altimeter and 5G (https://www.faa.gov/sites/faa.gov/files/2022-01/CAN-2022-01.pdf)

Pilot DAR

18th Jan 2022, 20:26

The Canadian news perspective:

https://www.cbc.ca/news/world/5g-rollout-delayed-american-airlines-travel-disruptions-1.6319172

compressor stall

18th Jan 2022, 20:38

Rumours Emirates not going to some US ports due this issue?

visibility3miles

18th Jan 2022, 20:45

Latest news:

AT&T and Verizon to limit 5G network rollout near airports after airlines warn of major disruptions (https://s2.washingtonpost.com/35ca8e5/61e720abef876836512eaa50/596c2c4fae7e8a44e7e98fb2/3/13/61e720abef876836512eaa50)The wireless companies said Tuesday they would limit the rollout after U.S. carriers complained of the potential for interference with airplane safety technology. The telecom firms have twice delayed the rollout to give aviation safety regulators more time to analyze potential interference with devices on planes that are critical for landing in poor visibility
By Ian Duncan (https://www.washingtonpost.com/people/ian-duncan/)
and
Lori Aratani (https://www.washingtonpost.com/people/lori-aratani/)

Today at 3:16 p.m. ESTWireless companies AT&T and Verizon said Tuesday they would limit the rollout of 5G networks near airports after airlines warned of major disruptions because of the potential for interference with airplane safety technology.Wireless towers in other locations are set to come online Wednesday as scheduled. The telecom firms have twice delayed activating the towers in recent months — which will deliver higher-speed Internet — to give aviation safety regulators more time to analyze potential interference with devices on planes known as radio altimeters. The devices measure how high planes are flying and are critical for landing in poor visibility.
The two wireless carriers issued statements expressing disappointment that the Federal Aviation Administration had not been able to resolve the safety issues.

“At our sole discretion we have voluntarily agreed to temporarily defer turning on a limited number of towers around certain airport runways as we continue to work with the aviation industry and the FAA to provide further information about our 5G deployment, since they have not utilized the two years they’ve had to responsibly plan for this deployment,” AT&T said.

It was not immediately clear whether the steps taken by the two wireless carriers would alleviate the concerns airlines have expressed.

GlobalNav

18th Jan 2022, 21:17

One could argue, that the government should never have sold this critical band in the first place.

As for the Air / Ground switching, I imagine that the good old WOW switch was thought old fashioned by the software boys.

You could argue that, but realistically the "government" is big and not monolithic, at least in America. The FCC and FAA belong to different cabinet level departments and are strongly influenced by very different political forces. At the working level they, perhaps, work better together than at the executive level, but cooperation is not great and they have very disparate perspectives of the public interest they presumably serve.

With clear and widespread notification of the public safety risk, the 5G industry has perilous liability waters to swim through. They just cannot say they didn't know. This may have more influence on the outcome than actions taken by the government.

WillowRun 6-3

19th Jan 2022, 00:34

GlobalNav's answer strikes me as quite very accurate. The respective "complex" or sometimes, "interagency complex" or just "interagency" surrounding each of these two disparate federal agencies are different in deeply rooted ways. Congressional staffs (primarily Committees) at senior levels, lobbying groups and lobbyists including but not only through the so-called revolving door, law firms and p.r. firms - like, different sub-sub-cultures of the Big Show that is Washington.

Probably everyone has read material from the wireless carriers attacking the supposed delay the aviation sector has caused by not innovating, upgrading, and otherwise facilitating the commercial interests of the wireless industry. Some of those attacks are polished and some just bitter snark, but their points are the same. If only running a national civil aviation sector were that easy, simple or matter-of-fact. .....

Wonder what the aviation professionals here would say to this: ask the wireless commercial interests to make a list of all the principal and second-tier entities and authorities which would have had to sign onto, and implement, a detailed technical plan to upgrade all avionics (and airport configs, to the extent it matters) so that no 5G interference is expected or possible within generally and widely accepted risk tolerances. And it's not too late to make their list, and get on with checkin' it twice . . . The diverse financial resources, Congressional backing or clout, technical fidelity or virtuosity, overall organizational readiness, and no doubt other descriptive factors of these would-be actors in a Big National Upgrade Plan.... they'd be all over the map, no? So to attack the aviation sector by saying 'HEY you shoulda been ready for this!!' is, as this SLF/atty sees it, highly dishonest -- and bad policy, as it significantly, perhaps even fundamentally, misunderstands the NAS and the aviation sector.

If a combination of Scoop Jackson, Wm. Winpisinger, and Melvin Belli suddenly appeared, isn't it obvious this hybrid figure would demand to know, 'are you gonna let the phone company push you around?' I mean, no offense to AT&T and/or Verizon . . . . . well, maybe a little.

SomeDanceToRemember

19th Jan 2022, 03:02

Could this cause crashes? What mechanisms and procedures are there to prevent crashes if the radar altimeter malfunctions? What's the worst-case scenario?

DaveReidUK

19th Jan 2022, 07:27

Could this cause crashes? What mechanisms and procedures are there to prevent crashes if the radar altimeter malfunctions? What's the worst-case scenario?

Worth a read: TK1951 Accident Report (https://www.onderzoeksraad.nl/en/media/attachment/2018/7/10/rapport_ta_eng_web.pdf)

snowfalcon2

19th Jan 2022, 08:12

Sallyann1234

19th Jan 2022, 09:40

A question to the radio engineers among you: If you would need to design a radio altimeter today taking account of the increasing scarcity of radio frequency spectrum - what would be the minimum needed bandwidth including guard bands? I know it is always a trade off between cost, performance and need for spectrum, but looking at the whopping ~600 MHz now used by the radio altimeter service (including guard bands) one would think there would exist more spectrum-efficient solutions?
Briefly,
The band allocated internationally for this purpose is 4.2-4.4 GHz, so 200MHz wide. The adjacent spectrum either side is not officially guard band but allocated by national administractions, again within international regulations, in the knowledge of the radar and other systems.

The actual spectrum requirement of a radar transmission can be calculated from the pulse repetition frequency and pulse risetimes. I suspect that different manufacturers may use their own proprietary parameters. But prima facie the 200 MHz bandwidth seems quite adequate. The problem seems to be that the radar receivers respond to a much wider bandwidth than the 200 MHz, so they are susceptible to strong signals in adjacent frequency bands.

This has not been a problem until now, with 5G cellular being introduced into spectrum below the radar band. How much the receiver bandwidths can be reduced without limiting their performance is a matter for the manufacturers, but a simple modification to existing fitted equipment seems impractical.

There is also the issue of 5G transmissions radiating outside their own band and into the radar band. These are quite tightly controlled and are likely to be less of a problem.

The interference potential from 5G in C band is greater in the US because the allocated band goes up th 3.98 GHz, whereas in some other places including Europe it stops at 3.8 GHz. Also higher transmit powers are proposed

edited to add:
WillowRun 6-3's description of the relationships between the FAA and FCC may well explain the disgraceful lack of prior testing to evaluate potential problems, during the ample time available to carry out the work.
Was this a standoff, with each leaving the other to do something about it? If anyone is now suffering financial loss, they should be looking to see who was responsible.

ex-Dispatcher

19th Jan 2022, 10:49

Not a pilot but a PNT Technologist now (and ex FAA aircraft dispatcher)

The FCC in the US have made three big decisions recently in terms of opening up spectrum

Opening up C-Band frequencies for 5G
Ligado Networks allowed to repurpose L-band spectrum
Repurposing the 5.9 GHz “safety band”

In a nutshell, decision 1) has caused the RA problems, decision 2) will cause risk to GPS services and decision 3) may put transport (automotive) safety at risk
The spectrum is congested, there is increasing demand for fast broadband access practically everywhere, so perhaps its no surprise that we are losing the safety margins that we had around some of these critical services.

But in making these decisions the FCC are putting the burden of proof firmly onto the parties that oppose the introduction of a new technology, rather than the incumbent (I provided a reference to the presentation on the legalities which was made at the recent PNT Advisory Board meeting by Jeff Shane, IATA Representative & PNTAB Member. It's a comprehensive summary of the decision making process and the flaws in it.

Decision 2) the repurposing of the L-band spectrum is the issue I'm most involved with right now - this also has the potential to cause issues to aviation

tdracer

19th Jan 2022, 16:13

As for the Air / Ground switching, I imagine that the good old WOW switch was thought old fashioned by the software boys.

Rather ironically given the current issue, WOW (prox sensors) was not considered sufficiently robust with regard to ElectroMagnetic Interference and is typically single thread. LRRA designed and certified as a Critical "DAL A" system and nearly always has redundancy.

When we did the 747-8, we used a combination of WOW and LRRA for critical engine control functions - basically five sources (two WOW, three LRRA) - to indicate "On Ground" for critical functions we required three on-ground indications, with at least one each from WOW and LRRA.

FullWings

19th Jan 2022, 17:39

A question to the radio engineers among you: If you would need to design a radio altimeter today taking account of the increasing scarcity of radio frequency spectrum - what would be the minimum needed bandwidth including guard bands? I know it is always a trade off between cost, performance and need for spectrum, but looking at the whopping ~600 MHz now used by the radio altimeter service (including guard bands) one would think there would exist more spectrum-efficient solutions?
It’s a long long time since I was in practice in another life, but with just what I remember, I would posit hardly any. The aggressive way modern comms cram as many bits as possible into each Hz of bandwidth, means that it looks effectively like a broad swathe of noise; completely different to a radio altimeter which is just trying to determine time of flight of a reflected pulse, and there are multiple ways to make this more robust. They are affected by doppler effects but not that much, given aircraft vertical speeds compared with c. I’m sure there are technical edge cases where one could interfere with the other but from a (now) lay point-of-view, it just doesn’t feel that likely.

Filter technology, both analog and digital, is pretty advanced these days, and out-of-band rejection a foregone conclusion. I can only think that old designs of RAs are really, really bad if they are susceptible to something hundreds of MHz away; certainly the 5G transmitters won’t be leaking onto the RA band. I haven’t heard of anyone actually being able to generate false RA readings with 5G signals, so it seems to be conjecture at the moment...

albatross

19th Jan 2022, 18:12

Imagine the litigation nightmare if Radar Altimeter interference due to 5G is even suspected in an aviation incident or accident.
FAA, FCC, 5G providers, airlines, manufacturers, airport authorities and anyone else down to the janitor will be sued. The list will be endless. Lawyers , high end car dealers, yacht brokers and real estate agents in Florida and the Caribbean will be most pleased.

visibility3miles

19th Jan 2022, 21:22

But with 5G access, they could report any accidents very quickly!

(Apologies in advance for tasteless joke.)

Klauss

20th Jan 2022, 00:29

Hm.... yes, the 747-8 has many of everything. It even has a system that protects against tailstrikes and looks a bit like the 737-Max system that didn´t work right at first. I wonder how the 3 LRRA cope with the 5G stuff...?

Rather ironically given the current issue, WOW (prox sensors) was not considered sufficiently robust with regard to ElectroMagnetic Interference and is typically single thread. LRRA designed and certified as a Critical "DAL A" system and nearly always has redundancy.

When we did the 747-8, we used a combination of WOW and LRRA for critical engine control functions - basically five sources (two WOW, three LRRA) - to indicate "On Ground" for critical functions we required three on-ground indications, with at least one each from WOW and LRRA.

RobertP

20th Jan 2022, 01:23

There are two types of aircraft “Radio Altimeters. I will not go into the technical details for each type.
The most common uses FMCW to determine altitude simplistically by measuring the frequency shift of the received signal from that of the transmitted signal.
less common are pulsed , should be called “Radar Altimeters” as they use pulse techniques, i.e. the altitude is determined by the time taken for the transmitted pulse to be received, different technique from FMCW but less liable to interference, but tend to cost more.

hans brinker

20th Jan 2022, 04:13

Worth a read: TK1951 Accident Report (https://www.onderzoeksraad.nl/en/media/attachment/2018/7/10/rapport_ta_eng_web.pdf)

As a dutch pilot, I have read it more then once. If the RA had not malfunctioned, the crash would not have happened. If boeing had explained in their manual better what a RA failure could do to the ATHR, the crash might not have happened. If the pilots had realized that the numerous gear warning were related to an RA failure, the crash might not have happened. If the pilots had looked at the airspeed in the 30 seconds before the crash, it should not have happened. If they had responded correctly to the stall warning the crash would not have happened.

But I think that is different from the current discussion. Apparently, on the 787 the RA is even further integrated into the system, to the point that spoilers, reversers and autobrakes are affected, because the RA is part of the WOW, would not be surprised if the same applies to the MAX. Nothing from Airbus yet, but they aren't necessarily better about keeping the crew in the loop. I am really happy I don't fly raw data NDB approaches without EGPWS anymore, but the amount of automation autonomy the current aircraft have sometimes scares me.

Edit: just got a memo that on our A320 we can’t use the MEL for LGCIU2 “out of abundance of caution” for unknown risk related to 5G.

Superpilot

20th Jan 2022, 14:28

Nothing from Airbus yet, but they aren't necessarily better about keeping the crew in the loop.

The Airbus RA1+2 ECAM is a beast. Definitely "keeps you in the loop" and things get even more exciting when the gear goes down. This fault is practiced in the sim quite often. The implications of this failure are well known to anyone flying the Airbus. And because an Airbus's thrust levers do not move by themselves and because power reduction has to be accomplished manually (except in an Autoland situation) you are not going to be susceptible to the kinds of issues a Boeing is. Airbus automation is superior in functionality and safety compared to a Boeing (I've flown both).

GlobalNav

20th Jan 2022, 21:36

Could this cause crashes? What mechanisms and procedures are there to prevent crashes if the radar altimeter malfunctions? What's the worst-case scenario?

Invalid data from the radio altimeter could have the most hazardous impact on automated systems used for low visibility approaches and landings. The AD is intended to prohibit the use of such systems in the proximity of 5G transmissions that could interfere with the radio altimeters. What this means is huge change in airline operations, even in good weather, because such systems are routinely used. If low visibility conditions exist, then certain Category 1, Category 2 and Category 3 operations could not be conducted, creating major backups and delays at the airports they are established for.

albatross

21st Jan 2022, 13:01

I am surprised there is not a class action lawsuit against the FCC and 5G Cell phone providers filed by the airlines, AOPA and others for the cost of upgrading aircraft radar altimeters and loss of revenue due to cancelations caused by the inability to use approaches where DH is based on radalt.

The FCC certainly dropped the ball on this in granting the Cell providers the use this frequency spectrum.
The providers are at fault for implementing this knowing the problem existed.
“Well, we gave you time to prepare.” IE “Spend millions to upgrade your systems” doesn’t cut it.

FiveGirlKit

21st Jan 2022, 13:25

...... If the pilots had looked at the airspeed in the 30 seconds before the crash, it should not have happened. I.....

Maybe it is insensitive to highlight this on a pilot's forum, but the crew* missed many things in those 30+ seconds, at a point in the flight where their attention should have been at maximum (stay away from the edges of the air).

They missed multiple warning signs:
- rad alt height indication mismatch
- autothrottle indicating ‘retard flare’ mode
- throttles retarding
- engine indications showing idle
- speed decreasing
- speed colour change and flash
- AoA increasing
- pitch increasing to 17 degrees
- too much sky in the windows
- did I miss anything?

*"As this was a ‘Line Flight Under Supervision’, there were three crew members in the cockpit, namely the captain, who was also acting as instructor, the first officer who had to gain experience on the route of the flight and who was accordingly flying under supervision, and a safety pilot who was observing the flight."

"Safety pilot" :rolleyes:

My point is that avionics do fail, but the crew is meant to monitor and do something about it.

GlobalNav

21st Jan 2022, 23:26

Maybe it is insensitive to highlight this on a pilot's forum, but the crew* missed many things in those 30+ seconds, at a point in the flight where their attention should have been at maximum (stay away from the edges of the air).

They missed multiple warning signs:
- rad alt height indication mismatch
- autothrottle indicating ‘retard flare’ mode
- throttles retarding
- engine indications showing idle
- speed decreasing
- speed colour change and flash
- AoA increasing
- pitch increasing to 17 degrees
- too much sky in the windows
- did I miss anything?

*"As this was a ‘Line Flight Under Supervision’, there were three crew members in the cockpit, namely the captain, who was also acting as instructor, the first officer who had to gain experience on the route of the flight and who was accordingly flying under supervision, and a safety pilot who was observing the flight."

"Safety pilot" :rolleyes:

My point is that avionics do fail, but the crew is meant to monitor and do something about it.

And we have accident history that your latter point has not been met in numerous fatal events.

Lake1952

22nd Jan 2022, 15:53

So for the last several days, the several flights out of KEYW, Key West, destined for the Northeast (EWR or LGA) have flown a short distance to other southern Florida fields (RSW, MIA, FLL, MCO OR PBI) to take on more fuel before continuing the flight to its destination. These are all E170 flights flown for UA and DL by Republic Airways. KEYW has a short runway at 5,076 feet.

I understand the reason for limiting takeoff fuel weight has to do with the E170 EICAS logic which inhibits certain warning messages below 400 feet AGL as judged by the RA. Because of possible 5G interference with the RA, these inhibited messages may appear on the takeoff roll causing confusion. Since one of the potentially no longer inhibited message has to deal with brake failures, so to deal with that worst case RTO scenario,, takeoff weights are significantly reduced!

Who thinks this stuff up? And why is the 5G band an issue at Key West if it has allegedly been disabled near airports?
So far, the 5G interference issues seem centered around stations with CAT 2 and CAT 3 ILS approaches. The 5G is probably still operating at Key West because it doesn't even have an ILS approach .

Are there other issues having to do with potential 5G interference unrelated to advanced ILS approaches?

RatherBeFlying

22nd Jan 2022, 16:22

5G SNAFU was Avoidable (https://www.nytimes.com/2022/01/19/opinion/5g-airports-cellular.html)

Larry Kudlow, who headed President Donald Trump’s National Economic Council, even bragged about blowing off the F.A.A., saying on his Fox Business show, “We ignored them because the science said don’t worry about it.” He added later, “We actually fought the F.A.A. and we won.” It appears now that the Trump administration won the battle but not the war. One result of the extended conflict between the F.C.C. and the F.A.A. is that even now, nearly a year after the spectrum for 5G was auctioned off, the F.A.A. is still at the stage of information-gathering as it moves toward eventually issuing new requirements for radar altimeters. It is likely to take five years for all altimeters to be upgraded.

WillowRun 6-3

22nd Jan 2022, 17:40

Props to the NYT "Opinion Writer" for mostly standing clear of the dispute about whether concerns of the air safety community are exaggerated or not. Still, a few observations are worth noting. First, a substantial brief with technical support has been pending on the FCC docket for months, trying to get the Commission to reconsider its prior determination. If "the science" (a phrase that ought to be taken out back and dispatched to its ancestors, for what science specifically ever is cited?) is so clear, would not FCC have issued a firm if not resounding affirmance of its earlier order?

And as NYT-Op-Wrtr says, or implies, who should the United States trust more about the safety of flight ops - the quite politicized FCC, or FAA? As to the latter, don't tell me that they're just backside covering after MAX - sure the FAA has got a blackeye from MAX but that holds zero (0) probative value on these issues. As to the former, well, heard of "net neutrality"? - kind of politicized, yes?

Even after all that, there's a big problem with "the timeline." So 5G as it is waiting in the wings to become operational (.... sorry) exposes the decades-old outdatedness of certain avionics systems and, relatedly, the roles played, the functions performed that is, by those systems in certain types of transport category aircraft. So the wireless folks and FCC argue, hey, you should have been ordered to retrofit. Just like that? Who pays? What about developing the standard to be met, when did that get to be done by fiat? And let's have a discussion about usefully pertinent case studies of previous FAA programmatic efforts to require retrofit of longstanding systems, by all means. Noise abatement and quieter engines, that might be a case study of relevance. And it certainly didn't happen quickly. Are there other past instances of FAA in effect requiring major segments of the nation's airliner fleets to be re-equipped in some substantial way? I'm really asking, not rhetorical only.... maybe there is a prior example that supports FCC's assertions here and if so, this SLF/atty wants to know what it is.

Not least, its's not like the pandemic is quite an opportune time to tell airlines to re-equip these systems.

Last, the major airline industry trade association seemed quite ready to haul FCC into federal district court. While it isn't something one is taught in law school, instinctive lawyerly thinking strongly suggests FCC would have been handed its.... hat, coat and keys by the court. If there are legal eagles out there (sorry, Larry K, talk-tv does not count) who disagree, let's hear from them.

DaveReidUK

22nd Jan 2022, 18:15

exposes the decades-old outdatedness of certain avionics systems

Alternatively, it simply illustrates the inadvisability of having two disparate applications occupying pretty well the same waveband.

Lake1952

22nd Jan 2022, 23:10

And it's not just ops on foggy nights that are affected ... the Key West comedy illustrates that the data provided by the RA influences the validity of automated messages, warnings and alarms in perfect weather.as well. Everything is integrated.

Guessing that without an ILS approach, nobody thought that the 5G at EYW mattered? It's also a question of how rigid the FAA and manufacturers and carriers want to be. What's going on in EYW may actually be overkill? I don't fly airliners, so it's not for me to opine on how safety measures can be shaved. But dispatching flights in a low fuel state so that a RTO can be accomplished without resorting to brakes in case the brakes have failed unbeknownst to the crew due to a logic error in the EICAS caused by 5G interference with the RA seems like a bit of stretch. But like I said, not my area of expertise.

RatherBeFlying

22nd Jan 2022, 23:10

The FCC is about to learn about the amount of time and consultation it takes to develop or revise a TSO:p

Lake1952

23rd Jan 2022, 00:57

OK, read this on another site.. other impacts of RA interference besides low IFR approaches. Don't know if all is true, but here goes. The B777 uses RA data to avoid tailstrikes on rotation. The 787 and the Max use RA data to allow spoiler deployment and thrust reversers. So if the RA doesn't recognize it is on the ground, possibly no thrust reversers or spoilers?

787the 787 and MAX use the radar altimeter for things like thrust reverser and ground spoiler deployment. There are situations where the aircraft, despite having landed, might think it is still airborne and not allow deployment of the aforementioned systems which would greatly affect performance. and MAX use the radar altimeter for things like thrust reverser and ground spoiler deployment. There are situations wherethe 787 and MAX use the radar altimeter for things like thrust reverser and ground spoiler deployment. There are situations where the aircraft, despite having landed, might think it is still airborne and not allow deployment of the aforementioned systems which would greatly affect performance.

The 777 has a fairly unique issue. It uses the radar altimeter for the tailstrike avoidance system, so there is a concern that the aircraft might not allow the pilot to pitch the aircraft properly because it thinks the aircraft is about to strike the runway. the aircraft, despite having landed, might think it is still airborne and not allow deployment of the aforementioned systems which would greatly affect performance.

The 777 has a fairly unique issue. It uses the radar altimeter for the tailstrike avoidance system, so there is a concern that the aircraft might not allow the pilot to pitch the aircraft properly because it thinks the aircraft is about to strike the runway.

GlobalNav

23rd Jan 2022, 02:06

ATC Watcher

23rd Jan 2022, 08:30

History likes often to repeat itself. I am unfortunately old enough to remember a very similar issue with ILS in the end of the 90s. Way before RNP and GPS it had been decided at ICAO level in 1978 that MLS would replace ILS by 2000 and ILS would be decommissioned by 2010. This was pushed by the US/FAA at the time as they manufactured the MLS , but in between GPS and WAAS came up and the US changed their minds, we know the rest and the fate of MLS.. But one interesting story happened : A guy (a single person if I remember correctly) in the early 90s, read that ILS was to be decommissioned by 2010 , its frequencies could be released , and there was huge pressure from commercial radios to extend the FM band , of which ILS is just adjacent .So he wrote to the ITU and the frequencies were released to ITU, which started to allocate the ILS frequencies to commercial users..
This was only discovered 10 years or so later and panic followed, in a similar situation s today with 5 G. It took great efforts and a couple of years. to secure the ILS frequencies back. The fact that Commercial radio were not expanding anymore as foreseen in the 90's helped ..

The difference with 5G here, as I understood it, is that the frequencies between 5G and RA are close to each other within the same band , but are separated, It is the use at the border of the frequencies and the eventual overlaps that are the issue. But the other way around too. 5G will be used for drones, cars, autonomous construction ( read crane operations) , etc.. and safety critical as well with loss of life possibilities, and those brand new systems are digital and can probably maintain the correct frequencies, which is not the case of the old technology used in outdated avionics. most of us carry. So the logical solution would be a modern updated RA module that would keep its own frequency accurately. That as I understand unfortunately will take time and will not be cheap.
Some other countries have introduced a large buffer between the 2 frequencies allocation hoping it will avoid the issue, we will see if that works, because the problem is not 5G is the old RA technology.

w1pf

23rd Jan 2022, 11:26

(SLF former microwave engineer here)
I doubt the issue is center-frequency control.
The problem is almost certainly out-of-band rejection and spurious emissions/responses.

Sallyann1234

23rd Jan 2022, 13:06

(SLF former microwave engineer here)
I doubt the issue is center-frequency control.
The problem is almost certainly out-of-band rejection and spurious emissions/responses.

Discussed up thread and illustrated here:
https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/1025x532/23_01_2022_14_02_34_06a8177b1ed210b8bae5954a1af47ec06340ddc0 .png
Source:
5G Interference Assessment Report (rtca.org) (https://www.rtca.org/wp-content/uploads/2020/10/SC-239-5G-Interference-Assessment-Report_274-20-PMC-2073_accepted_changes.pdf)

N.B. the 5G band shown 3700 to 3980 is the US allocation to cellular. In Europe the band is 3600 to 3800. Other administrations may also vary, depending on national requirements.

albatross

23rd Jan 2022, 20:35

People seem to mention “Outdated Avionics” as a big part of the problem a lot.
So what presently available “Modern Avionics” have foolproof protection against interference from 5G?
Also how much does this all dancing, all singing black box, it’s installation and testing going to cost?
It must be noted that the FCC in the USA sold off a wider frequency band closer to Rad-Alt frequencies than other countries. Thereby exacerbating the problem.

The terrible, uninformed media in the USA speaks only about Airlines and seems to ignore General Aviation use of Rad-Alts. Always funny to see a picture of a pressure altimeter in the back ground as the “Talking Head” looks concerned as he/she/it reads the tele-prompter.

If my outdated Rad Alt worked just fine why should I have pay for a new system because of 5G?

Imagine if you will a new neighbour moves in and plays very loud music on his deck 24/7.
You complain and he says: “Maybe YOU should pay to have your house soundproofed!”
(I made that up allegory to explain 5G interference to a non-aviation non-tech savvy friend.)
Are you going to be a happy camper? I think not.

Also imagine if 5G were to affect, for example some safety system in people’s cars…the screams of protest would be deafening.

MarcK

23rd Jan 2022, 21:18

If my outdated Rad Alt worked just fine why should I have pay for a new system because of 5G?
If my crystal controlled VHF radio worked just fine, why do I have to pay for one that can receive 100KHz channels?
If my 100KHz radio worked just fine, why do i have to pay for one that can transmit and receive on 50KHz channels?
If my 50KHz radio worked just fine, why do i have to pay for one that can transmit and receive on 25KHz channels?
If my 25KHz radio works just fine, why do i have to pay for one that can transmit and receive on 8.33KHz channels?

albatross

24th Jan 2022, 01:35

If my crystal controlled VHF radio worked just fine, why do I have to pay for one that can receive 100KHz channels?
If my 100KHz radio worked just fine, why do i have to pay for one that can transmit and receive on 50KHz channels?
If my 50KHz radio worked just fine, why do i have to pay for one that can transmit and receive on 25KHz channels?
If my 25KHz radio works just fine, why do i have to pay for one that can transmit and receive on 8.33KHz channels?

Apples and Oranges
I see your point but respectfully disagree with it.
Even if you took delivery of a new state of the art aircraft last week the modern Rad -Alt would not provide protection from interference caused by 5G signals. Does such tech even exist at this time?

I have no problems with paying to improve aircraft systems due to technology advancements which enhance such things as aviation safety, navigation accuracy, communications and weather avoidance.

I do find a problem with paying for new systems because the FCC auctioned off frequency bands to the highest bidder and this leads to costs to aircraft owners without compensation. Especially true as the FAA warned them of the potential interference problems.
All this so Cell Providers can make money and folks can download vital cute kitten videos at higher speeds.

cameltruck

24th Jan 2022, 03:23

In terms of new tech for the RA function, the designers of autonomous vehicles and e-crap spin-offs like emergency braking and lane change assist have developed very capable consumer grade systems that can detect at distance rapidly moving objects, work in congested and all-weather environments, can operate in busy radio clutter even on the same frequencies. These things operate in the 20Ghz or now more commonly around the 75Ghz bands, far away from the frequencies used by mobile telecoms.

E.g. https://www.bosch-mobility-solutions.com/en/solutions/sensors/front-radar-sensor/

They are still a very long way from aviation certification, however most of their development is being paid for by the automotive industry for their own markets. In an aviation context it also suffers from the need to acquire worldwide agreements/standards for frequency allocation use/purpose, which doesn't happen overnight.

The Nr Fairy

24th Jan 2022, 06:48

And yet ... https://www.theregister.com/2022/01/19/5g_airliners_solved_by_japan/

Sallyann1234

24th Jan 2022, 13:46

And yet ... https://www.theregister.com/2022/01/19/5g_airliners_solved_by_japan/
Yes. Japan and Europe have both studied the issue and found resolutions.

While FAA and FCC seem to have conducted a two-year face-off, neither doing anything to check whether the potential problem is an actual one.

WillowRun 6-3

24th Jan 2022, 15:31

Too early to engage the question, 'how is it that the massive bureaucracies in the U.S., at the federal level, could have fumbled this situation so badly?' While enough facts for a more complete post-mortem probably aren't yet known, this SLF/att'y wants to take a swing at it.

Perhaps "two-year face-off" is very descriptive, if your context is hockey. That is, bureaucracies of this size move in slow motion.....very slow motion.

Especially where complicated technologies (and engineering too, I think) are at the center of the question or questions. Consider a comparable situation--not aviation, but really all about complicated technologies and "Engin."

The U.S. National Orbital Debris R&D Plan was made final (in form) and published in the waning days of the prior presidential administration. It was done by - get this - four (4) levels of formal bureaucracy, plus a superior bureaucratic layer. A Working Group, of a Subcommittee, of a Committee, of the National Science and Technology Council, layered over by the White House Office of Science and Technology Policy. The Council, ostensibly anyway, coordinates in and among the Executive Branch, while OSTP, again ostensibly, advises the president. How this all works really, given that the president is the head of Executive Branch..... not for today.

So, if you've indulged this comparison of bureaucratic inertia so far, do you wonder how the R&D Plan is progressing? Public comments on the plan were solicited through the Federal Register, and three-minute timeslots were available for two "listening sessions." Despite some professional and academic interest I declined to participate at all - trying to say much of anything about a complicated (to say the least) technology-focused problem set in 3 minutes, that would insult any professional audience's intelligence. (The cognitive, not artificial....)

Yet, your bureaucracy at work. So, some Slayer of Bureaus is needed, I would suppose.

Less Hair

25th Jan 2022, 08:47

I hope the 5G guys are made to pay for this not the aviation industry. The 5G guys want to use bands that had been allocated to somebody else before.

Klauss

25th Jan 2022, 11:54

I hope the 5G guys are made to pay for this not the aviation industry. The 5G guys want to use bands that had been allocated to somebody else before.

I think that´s going in the right direction. There is the ITU, International Telecomunications Union, that coordinates frequency use worldwide. One of their principles is, that newcomers may not disturb established services (-slightly reworded, from memory) . So , this makes it clear that the 5G people have to design and operate their systems so as not to bug the radioaltimeters. Of course, it´s only an international, global agency - thus, their § may not apply in the US :rolleyes:

Winemaker

25th Jan 2022, 14:25

From the Seattle Times today:
As fog shrouded Paine Field in Everett Monday, Alaska Air regional carrier Horizon Air was forced to cancel all commercial flights in and out of the airfield because of limitations on low visibility flying imposed to avoid 5G interference.

Horizon is currently the sole airline operating commercial flights out of Paine Field and all those are flown on the Embraer E175, a 76-seat regional jet.

The limitations imposed by the Federal Aviation Administration to prevent interference with cockpit instruments have created a problem specific to that aircraft and certain airports, including Paine Field and Portland International Airport.

And further
Whether the FAA granted clearance depended on what model of altimeter was installed on each aircraft and also how close the cell towers at each airport were to the runways.

The altimeters on Horizon’s Q400 turboprop planes — supplied by Collins — allowed those aircraft to be cleared everywhere. But Sprague said that the specific Honeywell altimeter on the E175 jet required airport-specific limitations.

“The configuration of the Honeywell radio altimeter in the E175, and how it integrates with the other aircraft systems on the E175, are such that the the likelihood of interference from the 5G signal is greater,” said Sprague.

The FAA therefore cleared the E175 to use only runways further away from the cell towers.

Lake1952

25th Jan 2022, 19:04

E170/175s are really taking the brunt of this. As I have posted, it isn't always weather related either! Apparently so many EICAS warnings and system alarms have the RA wired into the logic tree of the E170/175 that at Key West with its short 5,000 foot runway, the type is significantly weight restricted on takeoff causing medium distance flights to have to fly over to southern FL airports like RSW, MIA, FLL and PBI to take on full fuel to reach their destination. It has to do with the possibility of a RTO and not be able to completely trust brakes/spoilers due to the RA being in the logic tree. I cannot give you the tech details accurately, so I will leave it at that.

Sallyann1234

26th Jan 2022, 09:18

Klauss

26th Jan 2022, 12:57

WillowRun 6-3

26th Jan 2022, 13:15

Not to revisit ... let alone in any detail or depth ... the significant body of evidence presented to FCC in the May 2020 motion for reconsideration, or in the Emergency Petition filed late last year, on behalf of principal aviation interests and interested parties.

But, I will say it is simply incorrect, invalid and wrong to assert that the safe, efficient, and resilient U.S. aviation sector, or the National Airspace System, can be put into experimental mode, on the basis that commercial entities and interests have invested capital. Or that other countries have taken their own decisions.

Sallyann1234

26th Jan 2022, 16:03

I don't see anyone suggesting that airlines should be experimenting. In the absence of properly constructed tests to establish acceptable parameters, the present wide operational restrictions seem to be the only safe option.
There was a two year window in which those tests should have been done, by the relevant authorities and not by the airlines. Someone now has to decide how to proceed, or the restrictions will remain.

I find myself to be repeating the same message - time to leave the thread.

tdracer

26th Jan 2022, 16:07

Has anyone yet demonstrated or reported actual interference to altimeters, of an extent to require these restrictions?
Are these restrictions to be maintained indefinitely, in the absence of proper tests?

Electro-Magnetic Interference can be very difficult to measure and evaluate. Even documented cases of EMI often can't be duplicated in the lab.
I recall one case many years ago - a flight crew on a Boeing aircraft started observing some very unusual avionics behavior. The cabin crew observed a passenger playing a gameboy type device - when they had the passenger turn it off the problem immediately went away. The airline actually purchased the computer game from the individual and gave it to Boeing to investigate - and Boeing could find nothing unusual about the device or duplicate any sort of unusual behavior :confused:
That being said, the FAA and FCC have done a horrible job of handling this issue...

Lake1952

27th Jan 2022, 21:10

Well, the Key West departures that pulled up short to refuel in South Florida have now been flying to their intended destinations nonstop. So either the 5G adjacent to KEYW has been shut down or whatever had to be done to verify the RA integrity of the E170/175 has been done.

Oldshredder

27th Jan 2022, 21:37

AT&T and Verizon paid close to $70 billion dollars for the spectrum they are using. The bureaucrats should figure out how they can safely use it.

Klauss

27th Jan 2022, 22:19

AT&T and Verizon paid close to $70 billion dollars for the spectrum they are using. The bureaucrats should figure out how they can safely use it.

Well, there is always the possility to negotiate, like about a refund, or acceptance of restrictions for a few $ ....
and there is the possibility of a serious mishap, with som people not around afterwards to pay taxes.

Choices.

GlobalNav

28th Jan 2022, 01:41

And still the issue is dealt with in the US on the basis of 'potential' and 'possibility' and 'likelihood' of interference to altimeters, which therefore requires extensive precautions and operational restrictions.

Has anyone yet demonstrated or reported actual interference to altimeters, of an extent to require these restrictions?
Are these restrictions to be maintained indefinitely, in the absence of proper tests?

Meanwhile the rest of the world has made its assessments, and got on with life as normal.

It’s not quite that simple. When systems are certified, they must be demonstrated to comply with the standards of performance in conditions that represent those expected to be found in service. Any certification applicant could justifiably object if performance tests were required in more challenging, nonrepresentative conditions. Radio altimeters and the flight control systems they interface with have been certified to meet known requirements in the appropriate conditions.

Now the the conditions are changing. Radio altimeters had been certified to sufficiently reject interfering signals and continue to meet required performance standards when 5G transmission in nearby wavelengths were not present. There was nothing wrong with these approvals. But not all currently approved radio altimeters type designs would be able to perform with the necessary accuracy and assurance in these new conditions.

One may point fingers only at the FCC and FAA, but remember they operate in the midst of powerful and disparate political influence by corporate interests and powerful politicians they support and rely on.

ImbracableCrunk

28th Jan 2022, 11:54

For those in FAA land, have any of you seen your 5G AMOC if you have one? If so, could you publish it here?

WillowRun 6-3

28th Jan 2022, 17:47

What GlobalNav said (155, above).

Also, I had not meant to be understood as saying that anyone had advocated actually experimenting.

Time perhaps will tell whether a difference that appears to exist between the FCC and the FAA is a real difference. FAA obviously is situated within and as part of the Department of Transportation, headed by a Cabinet Secretary. The head of FCC might have "Cabinet rank" (I don't know) but it appears there's a difference in operating as a component (in so many words) of the president's Cabinet, and being instead one among many federal agencies which, collectively, sometimes are referred to as "the inter-agency." In this matter, it sometimes seems like the prior administration strongly favored commercial interests in telecommunications, and applied pressure on and through FCC. Then the new administrstion took over, FAA regained its role as the heavier of the heavyweights, and because Cabinet agencies can apply more authority more quickly, FAA was effective in changing the game up.

Tom Wheeler, formerly head of FCC, published a piece a few days ago in which he asked if FAA was like the kid who "cried wolf" once too often. Perhaps surprisingly, his writing appeared to give good amount of credence to FAA and the aviation community's concerns. But overall, this tangle-up doesn't bode well for future, anticipated clashes of rival technological interests.

hans brinker

29th Jan 2022, 03:53

For those in FAA land, have any of you seen your 5G AMOC if you have one? If so, could you publish it here?

Not really comfortable publishing company manuals here. We do have it, it covers most, but not all of our airports.

ImbracableCrunk

29th Jan 2022, 14:49

Can you summarize?

hans brinker

29th Jan 2022, 16:44

Can you summarize?

Of all our regular allowed airports, destination, alternate, diversion, it is about 50% that don't have AMOC, for our regular scheduled most do, quick look is only 5 that don't, and at least 1 of those doesn't have CAT II/III. It just says: AMOC provides relief from AD2021-23-12, without any explanation of the how/what was done.

WillowRun 6-3

29th Jan 2022, 18:36

FAA statement as of 28 January, with regard to continued clarification of operational limits:

https://www.faa.gov/newsroom/faa-statements-5g

WillowRun 6-3

5th Feb 2022, 16:46

Testimony of FAA Administrator to House Transportation and Infrastructure Comm. on 5G rollout and impact of 5G generally on aviation safety. Though the Administrator's prepared remarks were brief, they nevertheless included references to efforts by FAA as well as certain aviation sector interests to alert the federal bureaucracy to anticipated problems.

link:
https://www.cnet.com/videos/faa-talks-5g-and-aviation-safety/

WillowRun 6-3

9th Feb 2022, 17:53

ALPA Pres. Joe DePete has sent strongly worded correspondence to the chair of the Aviation Subcommittee of the House Transportation and Infrastructure Committee. The letter follows subcommittee hearings last week.

“Given that the agency legally tasked with oversight of the telecommunications industry [the FCC] completely failed to provide critical information relevant to the safety of the U.S. airspace system and voluntary dialogue by private sector companies did not begin until the precise time their actions posed catastrophic harm to public safety, it is clear there is a systemic failure of governance over the wireless industry’s use of spectrum, disclosure of information, and licensing. This necessitates a redesign of the government’s authority over these providers, including granting affected agencies, like the FAA, authority to reject or modify new or expanded spectrum applications, as well as the ability to directly interact with the FCC. The hearing provided damning insight into how broken the federal radio spectrum and licensing process is in relation to aviation safety and the need for immediate reform.”

DePete also wrote, “FCC not only failed to heed our concerns, but they willfully neglected to carry out their regulatory responsibilities and ask licensees for critical data needed to plan for launching 5G while maintaining aviation safety. This failure on the part of the FCC has resulted in uncertainty, complexity, and increased workload for every flight.” DePete stated FCC never asked the wireless industry for the required data for conducting safety risk mitigation assessments. He also stated that cost for retrofitting commercial aircraft with interference-resistant radar altimeters would easily cost $100,000--$150,000 per aircraft and the FAA could take up to four years to approve this new equipment.

Some of DePete’s strongest statements were directed at the CTIA, the Washington, D.C. advocacy group which represents wireless carriers. It provided an “inadequate level of meaningful data” to “evaluate the 5G signal impact on radar altimeters” and ignored concerns for aviation safety. “It appears that [5G C-band carriers] Verizon and AT&T are beginning to understand the need to share data for the advancement of [aviation] safety, even if their trade association, CTIA, does not.”

The letter further looked into the near-term future and looming additional stressors upon the NAS. “As we look forward to new entrants to the aviation system—remotely piloted aircraft systems and drones, advanced air mobility, hypersonic aircraft, and commercial space operations—we need to make sure that these entities are also not impacted by 5G interference. A thorough review and risk mitigation of the systems used by these stakeholders is also needed before allowing 5G in the C-Band to continue expansion.”

So significant issues persist, though different factors may see the greatest emphasis - especially cost of retrofit, as well as developing standards by FAA. Little doubt cost (retrofit), and standards (new), will impact one another. Left for some other forum is any effort to address, much less redress, the bureaucratic or interagency inertia or turf-protecting (notice, as SLF/attorney I have not said "incompetence") by which this set of issues hit the fan.

fdr

20th Feb 2022, 14:30

Electro-Magnetic Interference can be very difficult to measure and evaluate. Even documented cases of EMI often can't be duplicated in the lab.
I recall one case many years ago - a flight crew on a Boeing aircraft started observing some very unusual avionics behavior. The cabin crew observed a passenger playing a gameboy type device - when they had the passenger turn it off the problem immediately went away. The airline actually purchased the computer game from the individual and gave it to Boeing to investigate - and Boeing could find nothing unusual about the device or duplicate any sort of unusual behavior :confused:
That being said, the FAA and FCC have done a horrible job of handling this issue...

TD' that sounds like an incident i had with a Motorola flip phone in 95 on a B763ER. driving along mind in neutral, get fire messages on both engines, APLT drops off, ATR quits, and we look at each other asking what did you do.... ? all lights go out and we put the APLT back on snooze and the ATR back into elegant level of noise mode, And relax, and 1 minute later, same thing again. Hmmm. Phone call from cabin.... hey cap, is it OK that the business pax is using his mobile phone. We ask the cabin chief to get them to turn it off, and the cockpit returns to normal. We then ask them to do the same thing again in 5 minutes and we get the same messages and they disappear when the lads turn the phone back off. We ask the passenger to give the phone to the chief to keep until we are on the ground. The report goes in. Years later, I'm in a tech pilot role on the 787 and in a meeting at fort fumble, the OEM says they have never had an incident on any brand X plane of interference. Brand X, I beg to differ.

HowardB

23rd Feb 2022, 17:21

This just popped up in one of my feeds today:
FAA says 5G could impact radio altimeters on most Boeing 737s (https://www.nasdaq.com/articles/faa-says-5g-could-impact-radio-altimeters-on-most-boeing-737s)

WillowRun 6-3

24th Feb 2022, 00:02

From the FAA website, the AD when published on Feb. 24 will be available at:
federalregister.gov/d/2022-03967, and on govinfo.gov

The AD is already linked on the FAA site as well.

WillowRun 6-3

30th Jun 2022, 18:57

EUROCONTROL has published a position paper discussing the issues presented by 5G technology advancement.
Available on the agency's website, its social media platforms, and here:
https://t.co/ZWddVufKLL

aek

2nd Jul 2022, 21:33

5G (or whatever "G") is not a technology per se. It's just a convenient banner providing a quick reference to the capabilities. The related radio access technology is more known as E-UTRA (and its derivatives). It'll be boring to dive deep into the details here (it's so huge topic) but technically, the difference between E-UTRA and the previous technology (UTRA) is very significant. Nothing in common, actually. E-UTRA is entirely different thing. It's much easy to learn and to implement, taking advantage of the computational capabilities in state of the art silicon chips. So it was a major clean-up from the engineer's perspective.

But the difference in RF spectrum usage efficiency between that two technologies is marginal. Both are good enough in that regard and both provides max. data throughput rate that is quite close to the theoretical maximum for given conditions. That's an important fact because it means that today, if you want more throughput, the only way to achieve that is to use more RF spectrum resources. You can't get noticeable gain by improving the technology itself (e.g. by inventing more efficient modulation schemes, using more advanced compression algorithms, designing better signaling protocols, and so on). The signal engineers are always happy to propose excellent technological improvements but that's simply because they are making their money from that. In fact, no additional spectrum allowance, no progress in the industry. So new wave of the spectrum wars.

I think that this particular issue will be sorted out very soon. Because it's not only the aviation community that's very upset by the new spectrum allocation, but the other corporations too. E.g. the GNSS guys are also among them, and I presume the military will also add their increasing weight to the push. So we will win the battle, no doubt. But I'm afraid we can't win the war in that way. Because if someone wants a resource very badly, he will keep trying to grab it. So he will keep trying to overturn a court decisions, to lobby for regulation changes, etc. After all, governments are elected by the business. No one will be happy, except the lawyers. It's a system problem.

Perhaps it'll be better, instead of trying to break the system, to find a ways to use it to our advantage. For instance, to set up a non-profit troll company, you can call it United Taxpayers Corporation, because each member of the club voluntarily taxes himself as much as he can to raise enough money to make a winning bid for the spectrum band on the auction. When the band is lawfully obtained, the company can install there a machine guns controlled by the image recognition software to prevent any human activity. Of course, it will not be a one time payment. Operational expenses, policing the band, providing enough physical security for the board members, guarding them against the criminals hired by the businessmen (they sure will), this all will bleed money constantly.

Seriously, widespread use of the troll company concept can cause to dramatic change in public behavioral pattern. You're paying not to get the thing but for the right to not have it. Too many useless things are out there. No wonder more and more people are starting to think how to prevent the others from making the things for profit. Clear example of missed opportunity is 4K TV (let 8K alone). Some clever guys learned how to pack excessive amount of pixels in square millimeter and wanted to make money from that. I was surprised on how welcomed it was by the public. Even with the special test images, the visual difference between 2K and 4K resolutions is barely noticeable on a screens of usual room TV size. While a 4K content requires noticeable more storage, bandwidth and eventually electricity and raw materials. So it's in fact inferior to 2K because the former is much less efficient. Now the same sort of guys are pushing for 5G to faster transmit that stuff to the tiny screens of mobile phones. Just insane. Something needs to be done to stop them. Different times, different priorities. Less is now more, etc. Welcome to the boring new world, gentlemen

albatross

3rd Jul 2022, 16:02

Since the recent US Supreme court decision hobbling the EPA’s regulatory authority appears, according to some reports, to also affect the FAA and I assume the FCC I wonder how that will further muddy the waters

aek

3rd Jul 2022, 18:46

-.-.
Hi, well, actually, there is a report for a 3G / 4G installation. Quite severe interference.

To don't drift well off topic. The G grade system is decoupled from the technology. It just indicates how fast the user equipment (e.g. a mobile phone) can exchange data with the tower. It says nothing about how it is achieved. It's perfectly possible to design a UE for the same data rate using different radio technologies. It was exactly the case for 3G/4G. Again, UTRA is CDMA-based while e-UTRA (LTE) is OFDM-based. So two different radio signals that can result in two different interference effects in the DUT. Mentioning of a meaningless marketing terms in a technical report renders the document equally meaningless. Too greedy to hire an experts in the field.

Anyway this all is at a very early stage indeed. To make it more complex, most UE integrates multiple modems, one for each supported radio access technology. So there are a GSM modem, a WCDMA modem, and an OFDM modem. The UE can switch between them very easy, as needed. For instance, in early years of LTE, it was used exclusively for data calls. So for every voice call, the UE had to fall back to WCDMA, using the same tower. Voice call support was added to LTE much later, under the name of VoLTE feature. But the old equipment can still be in the field. Next, two LTE flavors are defined, FD and TD (the latter is primarily for use in China). Again, two slightly different radio signals. Definitely there are something more I'm not aware of.

For sure it will take years and years to come up with a more-less meaningful results. A huge and expensive efforts. Very happy I don't have to take a part.

kiwi grey

4th Jul 2022, 04:34

Since the recent US Supreme court decision hobbling the EPA’s regulatory authority appears, according to some reports, to also affect the FAA and I assume the FCC. I wonder how that will further muddy the waters
Remarkably quickly, as it happens.
SpaceX is in a fight with legacy Internet SATCOM providers - including Viasat - who are making representations to the FCC to "share" (I think SpaceX would say "trespass on") some frequencies SpaceX is using for Starlink.
In this submission (https://licensing.fcc.gov/myibfs/download.do?attachment_key=16629529), SpaceX say

THE (FEDERAL COMMUNICATION) COMMISSION’S AUTHORITY OVER SPACE SAFETY IS UNTESTED
...
As the Supreme Court has recognized, though afforded wide latitude in its supervision over communication by wire and radio, "the Commission was not delegated unrestrained authority," and the public-interest standard "is not to be interpreted as setting up a standard so indefinite as to confer an unlimited power." Rather, the Commission is required to evaluate license applications taking cognizance of matters within the Commission’s expertise as envisioned by Congress. ... The Commission should ignore Viasat’s misguided invitation to stretch the public interest standard past the breaking point, which would put the Commission’s authority over space sustainability at risk.
I.E. the FCC's authority would be "at risk" of the SCOTUS finding it has no power at all in this area, in line with their recent EPA ruling, if 'someone' were to take it all the way to the SCOTUS.

aek

4th Jul 2022, 20:12

WideScreen

5th Jul 2022, 04:54

Remarkably quickly, as it happens.
SpaceX is in a fight with legacy Internet SATCOM providers - including Viasat - who are making representations to the FCC to "share" (I think SpaceX would say "trespass on") some frequencies SpaceX is using for Starlink.
In this submission (https://licensing.fcc.gov/myibfs/download.do?attachment_key=16629529), SpaceX say

I.E. the FCC's authority would be "at risk" of the SCOTUS finding it has no power at all in this area, in line with their recent EPA ruling, if 'someone' were to take it all the way to the SCOTUS.
This dispute highly resembles the Musk approach regarding "the winner takes it all" and -Musk like- "I declare to be the winner, so I take it all". Kind of Trump behavior.

WideScreen

5th Jul 2022, 05:09

BTW, almost forget to mention the most important factor in any outdoor activity. Weather. One of the advantages the E-UTRA technology does provide is better power management. Every UE periodically measures quality of the received signal and reports the results back to the tower. So both can adjust the parameters of radiated signal, including Tx power, to maintain reasonable error rate in the channel. In that way, the system can quickly adapt to the changes in signal propagation conditions, which are obviously weather-dependent for the frequency band in scope. So there is the possibility that in certain weather conditions (heavy rain, fog, etc.), when the information provided by the victim device is most important, the UE will generate more interference
There are some more differences. The 5G tends to be significantly higher base frequencies, resulting in shorter ranges and as such, the opportunity for more, but smaller in size cells. Also, 5G does come with many more channels, which can be combined in one connection.

Because of the significantly higher 5G frequencies, the wavelength is much shorter, with the consequence that shielding appropriate for 4G signals, suddenly starts to let 5G radio waves leak through, causing interference. Compare that to the cable TV signal distortion with the 4G introduction, solved by improving the TV cable shieldings. Note: Not all 5G frequency bands are higher in frequency as the 4G, some share, etc.

Add to that, that the 5G bands tend to be much nearer in frequency to the aviation/GPS vulnerable frequencies (combined with the broader 5G modulation spectrum used for a channel and as such more adjacent channel interference), and it is understandable, the 5G introduction is not a simple "let's go", as has been done until now.

Sallyann1234

5th Jul 2022, 08:39

WideScreen

5th Jul 2022, 14:52

The present concerns are not relating to 'significantly higher frequencies' but to C band, between 3 and 4 GHz. The precise relationship between the mobile and aeronautical services is documented in detail earlier in this thread. There are indeed long term plans for much higher frequency bands for 5g, but they are still in the field of research.
Yep. Currently, the use of the higher frequencies is limited, though, IF 5G gets approved, the higher frequencies will become used more widely and the chance of RA disruption goes up.

As for interference to GPS, the new cellular band at 3GHz is much further from the GNSS band than the older cellular bands. There doesn't seem to be any interference related to to those. Indeed modern smartphones have cellular radios and GPS receivers working within the same device.
Yep, interference does not have to be an issue, though, if you do have legacy equipment, the "shielding" is not enough to have the 5G and RA bands this close together. Add that 5G does have multichannel and a wider spectrum, and you can see a higher chance of low level signals stray into the RA bands at a signal level, that the legacy equipment in the airplanes does get confused.

Sallyann1234

5th Jul 2022, 15:09

WideScreen

6th Jul 2022, 02:34

What do you mean, IF 5g gets approved? It's been in use around the world for a couple of years!

It's far too late now to discuss this in such generalities. The potential for interaction between C band cellular and the aeronautical service just above in frequency is very well known, and discussed in great detail further up this thread.
Apologies, let me be more clear about "approved". The technology is there, the equipment is there, the equipment is being used. The use of the higher frequencies as well as the use of the "4G" frequency bands around airports is subject to "permits", which is the subject of this thread, being potentially dangerous for legacy RA and GPS based equipment. Once those permits are granted (IE administratively approved by the governments), the roll-out of the use of the higher 5G frequencies as well as 4G type frequencies around airports starts (or maybe better "continues"), without further blocking.

Connie Wings

5th Sep 2022, 15:25

Hi, Folks,

Does anybody know if there is 5G interference on aircraft's RAs operating in Canada airports?

Thanks

nnc0

5th Sep 2022, 18:44

Hi, Folks,

Does anybody know if there is 5G interference on aircraft's RAs operating in Canada airports?

Thanks

To address what I think you are asking - TC is not issuing any ADs against any Canadian airport so there are no restrictions to/from any Canadian airport due to 5G interference.

I believe Canada uses different frequencies than the US and at lower power levels. The 5G towers are also configured differently for transmission.

WillowRun 6-3

24th Nov 2022, 03:43

"Airlines for America joined other aviation groups and companies in an open letter to the Federal Aviation Administration calling for an extension of 5G C-Band mitigation measures by wireless carriers as airlines work to retrofit aircraft. 'Our aviation coalition strongly believes that instead of once again waiting until the eleventh hour, now is the time for the leadership at federal agencies and the White House to implement a solution that allows 5G to move forward and avoid further flight delays and cancellations,' the letter states."
A4A SmartBrief, Nov. 16, 2022.

[reproduced verbatim below as a public information service]

___________

November 15, 2022

The Honorable Brian Deese
National Economic Council Director
Executive Office of the President
1600 Pennsylvania Avenue, NW
Washington, D.C. 20500

The Honorable Gina M. Raimondo
Secretary of Commerce
U.S. Department of Commerce
401 Constitution Avenue, NW
Washington, D.C. 20230

The Honorable Pete Buttigieg
Secretary of Transportation
U.S. Department of Transportation
1200 New Jersey Avenue, SE
Washington, D.C. 20590

The Honorable Alan Davidson
Assistant Secretary of Commerce for Communications and Information
National Telecommunications and Information Administration
U.S. Department of Commerce
1401 Constitution Avenue, NW
Washington, D.C. 20230

Mr. Billy Nolen
Acting Administrator, Federal Aviation Administration
800 Independence Avenue, SW
Washington, D.C. 20591

Dear Director Deese, Secretary Raimondo, Secretary Buttigieg, Assistant Secretary Davidson and Acting Administrator Nolen:

It has been more than a year since a coalition of aviation stakeholders met with the National Economic Council (NEC) to discuss the need for C-Band 5G implementation to occur without sacrificing aviation safety. This meeting came after years of meetings and letters to the Federal Communications Commission (FCC), the National Telecommunications and Information Agency (NTIA) and the Federal Aviation Administration (FAA) raising significant concerns over the FCC’s auction of the 3700-3980 MHz spectrum (C-Band) and how it will impact radar altimeters (RAs) and the continued safe operation of commercial aircraft within the National Airspace System (NAS).

Those meetings, and the last-minute intervention of the Secretary of Transportation prevented the grounding of a significant portion of the US commercial aviation fleet. This marked the beginning of a collaborative and fruitful discussion between the telecommunication industry, specifically Verizon and AT&T, and the aviation industry. However, after a year of discussions and despite accommodations made by all parties, we are now seven months away from the next deadline, with significant risks still unresolved. We believe that by finding accommodations now, we can prevent another last-minute herculean intervention by the Administration and major disruption to our air transport system.

[The Honorable Brian Deese
November 15, 2022 Page 2]

The baseline situation remains unchanged. Our industry is strongly supportive of the deployment and implementation of 5G services nationwide, but we will not compromise aviation safety. Since our conversations last winter, the FAA has verified that certain aircraft RAs are susceptible to interference from 5G signals with a subsequent degradation of safety. Since January 2022 the FAA has documented over 100 FAA incidents of potential 5G interference, the majority of which were found to have a direct RA impact resulting in safety alerts by systems such as the Terrain Avoidance Warning System.

Unfortunately, the US government agencies do not appear to be on the same page with respect to these safety issues. As a result, aviation stakeholders are caught in the middle and ultimately passengers and shippers will be the ones who will bear the brunt of any operational disruption caused if this issue is not resolved.

Inter-agency government progress appears to be at a stalemate, while stakeholders are doing their part to address these issues. Aviation stakeholders, the FAA, and AT&T and Verizon have spent much of the last year trying to understand and implement what is required to continue safely operating aircraft in a 5G environment. This has required compromise, understanding, and investment by all parties. AT&T and Verizon implemented various mitigations, such as taking a phased approach to maintain lower power levels near airports and tilting antennas downward and have agreed to continue those mitigations through July 2023. The aviation industry is taking on the burden of designing and implementing a fleet retrofit to ensure that RAs are not compromised and retrofitting the entire fleet in less than two years is unprecedented.

Unfortunately, due to global supply chain issues, lack of a certified solution for one key RA, and the FAA only recently identifying the criteria for RAs that would not need to be changed, RA manufacturers and air carriers will likely be unable to fully meet either the December 2022 deadlines for smaller regional aircraft and many large transports nor the July 2023 retrofit deadline, though we continue to do everything within our power to do so. Further, all this investment will be wasted if a long-term mitigation plan is not put in place and codified in regulation, as additional wireless providers that have not been part of these interim voluntary efforts begin to provide services.

Our aviation coalition strongly believes that instead of once again waiting until the eleventh hour, now is the time for the leadership at federal agencies and the White House to implement a solution that allows 5G to move forward and avoid further flight delays and cancellations. The FAA recently sent a petition to the NTIA and FCC requesting a codification of reasonable mitigations. While we have not seen the FAA’s official petition to the NTIA and FCC, the FAA has informed stakeholders that to continue the operational safety of the NAS, the FCC rules and applicable Report and Order FCC-20-22 (https://www.fcc.gov/document/fcc-expands-flexible-use-c-band-5g-0) (https://www.fcc.gov/document/fcc-expands-flexible-use-c-band-5g-0)should be modified to address safety issues raised by the FAA. Furthermore, as the FCC, NTIA and FAA work to codify these requirements, it is critical to extend these mitigations through the end of 2023 to allow airlines time to complete the retrofit. We respectfully request that the US government share with stakeholders and the public the entire content of the petition by Friday November 18, 2022. The public has a strong interest in having access to the basis for concerns about aviation safety.

We will continue to be committed to finding reasonable solutions that allow implementation of 5G while addressing safety and operational disruptions in the NAS. Stakeholders cannot do this alone and we need the federal government to codify mitigations for all airports and extend the July 2023 and “Power Up” retrofit deadlines. The entire government must work together to ensure future 5G deployment is unencumbered and our aviation system remains the safest in the world. Aviation stakeholders call on the Administration to meet with us to discuss a way forward that will achieve the goal of moving 5G forward, while ensuring passengers and cargo reach their destinations safely and on time.

Sincerely,

Aerospace Industries Association
Aerospace Vehicle Systems Institute
Air Line Pilots Association, International
Airborne Public Safety Association
Airbus
Aircraft Electronics Association

[The Honorable Brian Deese
November 15, 2022 Page 3]

Aircraft Owners and Pilots Association
Airlines for America
Allied Pilots Association
Boeing
Cargo Airline Association
Collins Aerospace
Embraer
Experimental Aircraft Association, Inc.
Garmin
General Aviation Manufacturers Association
Helicopter Association International
International Air Transport Association
National Air Carrier Association
National Business Aviation Association
Regional Air Cargo Carriers Association
Regional Airline Association
RTCA
Thales

cc: Jessica Rosenworcel, Chairwoman, Federal Communications Commission
____________