5G versus commercial aircraft Radio Altimeters in the US, wtf?

[Gyro]

It looks as if US airlines and manufacturers are warning of a serious threat to flights when 5G is turned off in the US. Are they just scaremongering? Even the FAA seem to warning of possible interference problems with the Boeing 787.

Tell me somebody thought this through.

5G phones: How serious is the threat to US flights?

Ten leading US airlines are warning that the imminent rollout of 5G services could be disastrous.
They say the new technology could cause thousands of flights to be delayed, and risks leaving large parts of the US aircraft fleet grounded indefinitely.

https://www.bbc.co.uk/news/business-60042178

I suppose it makes a change from the other conspiracy theories!

[tom66]

The issue seems to be that the radio altimeters were made with the assumption that the band below 4.2GHz would be relatively clear.  Turns out it isn't any more.  But you should never make that assumption in a design so critical.

The solution is probably to fit a notch filter to the antenna input.  Such a solution, being aviation in nature, probably requires about as much paperwork as a 737 weighs.  But it would be a solution.     It's not uncommon to have parts retrofitted to aircraft well after they are manufactured, provided they're properly designed and approved.   I imagine it gets more difficult the further away from production an aircraft is... an old DC-10 / MD-10 might be a lot harder to retrofit, yet Fed-Ex still use them for freight.

Given it's an acknowledged issue, why are the airlines in this position?  It would have been known about for at least half a decade, but dither and confusion has led to a standoff between airlines and mobile carriers?

[Gyro]

Yes, it seems to be an adjacent frequency issue with small guard band (narrower than other countries?). It beggars belief that they haven't actually done some testing, let alone foreseen and implemented some mitigating measures. It sounds like more than old buses - Curious that the FAA and 787 are mentioned.

[G7PSK]

No idea how true this but I just heard on the news that 5G in the US is transmitted at a higher power than the UK and Europe and that is the concern. I would have thought that any power level would interfere at low altitude so it is most likely the US has gone with a different frequency, cannot think why as it would be better for travellers to have universal frequency bands, hardly likely that you would get trans atlantic interference as can happen between Europe and UK on the coast.   

[Gyro]

Just watching the story on the BBC news broadcast, apparently negotiations between the phone providers and airlines are happening 'at the highest levels of government'.

[rstofer]

This is a really big deal and it's all the fault of the FCC for not maintaining separation.  All they saw was dollar signs from selling spectrum without so much as a thought given to neighbors.  And what happened to the money?  It just got lost in the system somewhere.

The first airplane that drives into the ground is going to create a serious backlash!

It's not the FAA's fault, it's not the 5G industry's fault, it is ALL the fault of the FCC.  They are responsible for assigning spectrum.

[SiliconWizard]

Yep. This was discussed in another thread already. (In the Dodgy tech section?)
I agree with FCC's fault, this is their duty. And not to trigger polemics, but it just looks like the FDA these days. As soon as big money is involved, they seem to be getting suddenly blind. Or something.

[Gyro]

Yep. This was discussed in another thread already. (In the Dodgy tech section?)

Sorry, I must have missed that one.

Edit: I guess it must be getting mainstream media coverage now because it's one minute to midnight!

[SiliconWizard]

Yep. This was discussed in another thread already. (In the Dodgy tech section?)

Sorry, I must have missed that one.

Edit: I guess it must be getting mainstream media coverage now because it's one minute to midnight!

It was there: https://www.eevblog.com/forum/chat/faa-statement-on-5g
but I think there were a couple others too.
(Media coverage has its own agenda, so it's hard to conclude anything much out of it.)

[Gyro]

Update: The phone providers have just agreed to delay the rollout near airports again. It was due to go live tomorrow!

https://www.bbc.co.uk/news/business-60045077

[ve7xen]

It appears that not only is receiver desense due to adjacent power potentially a problem, spurious emissions from the 5G equipment are likely a problem as well, which is a lot more difficult to deal with than 'slap more filters on it'. Filtering is also not free, and will have an insertion loss cost, which will reduce sensitivity, and might then require more TX power to recover the SNR in such a sensitive system like a radar, and at that point you're redesigning the whole system. So, since this is aviation, you're talking about decades to get it implemented.

The report this article is based on is here: https://www.rtca.org/wp-content/uploads/2020/10/SC-239-5G-Interference-Assessment-Report_274-20-PMC-2073_accepted_changes.pdf and it is, IMO, quite comprehensive and models base station spurious and fundamental emissions, as well as those of phones that may be present on the ground or in the aircraft.

It seems likely to me that these bands will not be used near airports for these reasons.

And not to trigger polemics, but it just looks like the FDA these days. As soon as big money is involved, they seem to be getting suddenly blind. Or something.

"Regulatory Capture". Same thing with the FAA that indirectly lead to the 737MAX debacle.

[SiliconWizard]

It appears that not only is receiver desense due to adjacent power potentially a problem, spurious emissions from the 5G equipment are likely a problem as well, which is a lot more difficult to deal with than 'slap more filters on it'. Filtering is also not free, and will have an insertion loss cost, which will reduce sensitivity, and might then require more TX power to recover the SNR in such a sensitive system like a radar, and at that point you're redesigning the whole system. So, since this is aviation, you're talking about decades to get it implemented.

Yes. And people saying that they could just have anticipated future evolutions? 
So what's gonna happen with 6G, which is coming?

Most EMC standards still do not consider anything above 6 GHz. (IEC 61000-4-3...)

[Ed.Kloonk]

Yep. This was discussed in another thread already. (In the Dodgy tech section?)

Sorry, I must have missed that one.

Edit: I guess it must be getting mainstream media coverage now because it's one minute to midnight!

It was there: https://www.eevblog.com/forum/chat/faa-statement-on-5g
but I think there were a couple others too.
(Media coverage has its own agenda, so it's hard to conclude anything much out of it.)

Well, it doesn't help that the airlines all chase cheap seat ticket prices in a race to the bottom and when something bad happens they scream bloody murder.

[Homer J Simpson]

[Stray Electron]

  The news this evening says that they've known about this problem for over two years. I suspect that it's been far longer than that.  It all seems like the FAA and the FCC are both determined to be the final authority in this matter and neither one is willing to bend or to fix the problem.

   And in the meantime, the big cell phone companies are still determined to roll out their highly profitably 5G sham.

   The news also says that only 40% of the aircraft radio altimeters have been tested and are known to be safe with 5G.

   And at the same time, the cell phone companies are now telling the US public that they're already using 5G in 40 other countries, and implying that it's safe. What they're not telling the public is how many of those countries have any air traffic!  And they're also not telling the public that the 5G power levels in the US will be more than twice the level allowed in Europe and in other countries!

   I wonder what's going to happen when the first airplane crashes in the US and the authorities even suspect that 5G was the cause???  I foresee the 5G system getting shutdown totally and a lot of wankers will suddenly lose ALL of their cell phone toys!

[Ed.Kloonk]

   I wonder what's going to happen when the first airplane crashes in the US and the authorities even suspect that 5G was the cause???  I foresee the 5G system getting shutdown totally and a lot of wankers will suddenly lose ALL of their cell phone toys!

It depends on whether or not the altitude displayed is erroneous or non-existent. There are redundancies to establish altitude, it's when they all disagree with one another it can get dicey.

[syau]

It looks as if US airlines and manufacturers are warning of a serious threat to flights when 5G is turned off in the US. Are they just scaremongering? Even the FAA seem to warning of possible interference problems with the Boeing 787.

Tell me somebody thought this through.

5G phones: How serious is the threat to US flights?

Ten leading US airlines are warning that the imminent rollout of 5G services could be disastrous.
They say the new technology could cause thousands of flights to be delayed, and risks leaving large parts of the US aircraft fleet grounded indefinitely.

https://www.bbc.co.uk/news/business-60042178

I suppose it makes a change from the other conspiracy theories!

FAA Continued Airworthiness Notification for 787 https://www.faa.gov/sites/faa.gov/files/2022-01/CAN-2022-01.pdf

Likely similar notice for 777 and 747-8F will follow.

From the news, Japanese carrier already stop operating 777 into the State.

[LaserSteve]

This is not the first time. They should have learned about trust but verify, harmonics, and guard bands from the LightSquared fiasco.  There seems to be a problem with private consultants having more influence then what remains of the Engineering Staff at FCC.

I was reading a submission to the Commissioners the other
day from Megacorp G. saying they found no amateur radio or military use of 10 and 24 Ghz in northern California. Their flawed reasoning, was based on the fact that no licenses showed in the ULS data base with fixed locations near their test site.   Ok, so Amateurs don't log their spectrum usage like a corporate spectrum user, and Mil assignments are in the classified portion of the NTIA database, not ULS. So the letter reads "Dear Commissioners, we found this under utilized spectrum, please let us use it for our experiment".  As far as spectrum occupancy goes, nothing could be further from the truth.

Fortunately. DoD has a team that watches what FCC does, closely.

Steve

[pickle9000]

The RCTA report was done by volunteers. Not by the FCC FAA or airlines?

[Stray Electron]

From the news, Japanese carrier already stop operating 777 into the State.

   Not just the Japanese but another country as well. I'm not sure who but I know that the Indian government was very concerned over this.

   In my experience, the Japanese are very good and very thorough engineers and if they think that US 5G might be a problem then I think the US and other country should take this a lot more seriously than they appear to be.

  Rule #1. Follow the money.

     I wonder how much the US cell phone carriers expect to make from the 5G market?  And what would it cost them out of pocket to replace it with something else if the 5G system was completely shutdown?

[Gyro]

Rule #1. Follow the money.

     I wonder how much the US cell phone carriers expect to make from the 5G market?  And what would it cost them out of pocket to replace it with something else if the 5G system was completely shutdown?

Well they (AT&T and Verizon) paid the FCC $69bn for the rights to the C band frequencies, so they obviously expect to make a fair bit.

It does feel as if the FCC were squeezing the pips a bit... South Korea use 3.5GHz, Europe use 3.7GHz and the US, 3.98GHz.


Edit: According to what I saw on the BBC News last night, AT&T and Verizon weren't warned about the 'strings attached to their use of the frequency. In Canada, apparently the carriers have been instructed to orient their antennas downward near airports (don't know how well that works in practice).

[jonpaul]

Bonjour, Use of radio altimeter is less and less as airlines use GPS, ADS-B, etc which give more accurate alt info.

The admins mandarins with sinecures, have a lot of profit in this false fight.

FCC and FAA   politicians installed by recent US administration have replaced competent technical and engineering staff.

The guard bands are adequate as deemed by FAA and FCC before. Now at the last minute JoBi's idiots change the rules.

Expect more gov meddling in technical affaires to the detriment of our aviation AND telecom industries.

Just the rambling of an old retired EE

Jon

[ve7xen]

Bonjour, Use of radio altimeter is less and less as airlines use GPS, ADS-B, etc which give more accurate alt info.

What? No. GPS altitude is based on a geoid, not the terrain, so it doesn't replace the radar alimeter; it's not very accurate anyway, baro altitude is better. ADS-B altitude is transmitted by the aircraft so totally irrelevant here. The radio altimeter is really the only accurate source of distance-to-ground information available, which is used primarily for EGPWS and for callouts during landing, which are both pretty important and not practical without RA (though I think EGPWS might use its terrain database + ASL/calibrated altitude in addition to RA, the RA data is obviously much higher resolution).

Ultimately the fight is about money. Of course they can make the altimeters work just fine in the presence of this interference, but the interference is new and the equipment was designed around the usage regulations when it was created. Updating that equipment (or at least testing and re-qualifying it under new standards) is not free, and the aviation industry is quite reasonably chafing at the idea that they should foot the bill for telecom expansion that doesn't benefit them one iota.

[SiliconWizard]

Ultimately the fight is about money. Of course they can make the altimeters work just fine in the presence of this interference, but the interference is new and the equipment was designed around the usage regulations when it was created. Updating that equipment (or at least testing and re-qualifying it under new standards) is not free, and the aviation industry is quite reasonably chafing at the idea that they should foot the bill for telecom expansion that doesn't benefit them one iota.

Absolutely.

And in cases like this, if the State should have a role, it should at least be arbiter. Not just getting money from whoever gives more, including bribes. =)

[jpanhalt]

At first, I wondered why radio altimeters were such a big issue.  You have both a barometric altimeter, which is usually set to the local pressure, and on approach you have at least glideslope.  During the time I flew general aviation (US), two of my airplanes had radio altimeters, and I never used them except for amusement.

One problem is that when flying into airports in the SW and mountain states, the surrounding terrain can be well below the airport's elevation.  That might be bad, if one descended to 200 feet AGL before reaching the threshold.  Then I looked at the AD notices.  Apparently, in modern airliners, the radio altimeter is linked to important landing functions, such as reverse thrust and automatic braking.  The two "passengers" in the front seats cannot control those independently.

Once obvious solution seems to be ignored.  Why not have the pilots make those decisions?