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FAA ADs re 5G interference

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FAA ADs re 5G interference

Old 20th Jan 2022, 21:36
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Originally Posted by SomeDanceToRemember
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.
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Old 21st Jan 2022, 13:01
  #122 (permalink)  
 
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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.

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Old 21st Jan 2022, 13:25
  #123 (permalink)  
 
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Originally Posted by hans brinker
...... 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"

My point is that avionics do fail, but the crew is meant to monitor and do something about it.
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Old 21st Jan 2022, 23:26
  #124 (permalink)  
 
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Originally Posted by FiveGirlKit
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"

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.
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Old 22nd Jan 2022, 15:53
  #125 (permalink)  
 
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Another 5G Wrinkle

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?

Last edited by Lake1952; 22nd Jan 2022 at 16:45.
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Old 22nd Jan 2022, 16:22
  #126 (permalink)  
 
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The FCC Trumped the FAA

5G SNAFU was Avoidable

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.
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Old 22nd Jan 2022, 17:40
  #127 (permalink)  
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Retrofit - without delay!!

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.

Last edited by WillowRun 6-3; 22nd Jan 2022 at 18:06. Reason: typos
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Old 22nd Jan 2022, 18:15
  #128 (permalink)  
 
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Originally Posted by WillowRun 6-3
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.
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Old 22nd Jan 2022, 23:10
  #129 (permalink)  
 
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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.

Last edited by Lake1952; 22nd Jan 2022 at 23:23.
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Old 22nd Jan 2022, 23:10
  #130 (permalink)  
 
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The FCC is about to learn about the amount of time and consultation it takes to develop or revise a TSO
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Old 23rd Jan 2022, 00:57
  #131 (permalink)  
 
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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.

Last edited by Lake1952; 23rd Jan 2022 at 01:12.
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Old 23rd Jan 2022, 02:06
  #132 (permalink)  
 
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Originally Posted by Lake1952
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 .
Granted, but TR or spoiler activation at the wrong time could be bad too.
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Old 23rd Jan 2022, 08:30
  #133 (permalink)  
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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.
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Old 23rd Jan 2022, 11:26
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(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.
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Old 23rd Jan 2022, 13:06
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Originally Posted by w1pf
(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:

Source:
5G Interference Assessment Report (rtca.org)

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.

Last edited by Sallyann1234; 23rd Jan 2022 at 13:21.
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Old 23rd Jan 2022, 20:35
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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.
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Old 23rd Jan 2022, 21:18
  #137 (permalink)  
 
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Originally Posted by albatross
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?
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Old 24th Jan 2022, 01:35
  #138 (permalink)  
 
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Originally Posted by MarcK
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.

Last edited by albatross; 24th Jan 2022 at 02:00.
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Old 24th Jan 2022, 03:23
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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...-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.
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Old 24th Jan 2022, 06:48
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And yet ... https://www.theregister.com/2022/01/...lved_by_japan/
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