U.S. Airlines Warn of 'Catastrophic' Crisis With Impending 5G Rollout, AT&T and Verizon Agree to Delay Around Airports

[Devin Breeding]

Sounds like a future scapegoat for the airline’s massive labor shortage.

 

[TheFluffyDuck]

Just another case of America coming up with, or spruiking a technology (pay-wave credit cards, chipped passports, 5G, the metric system etc.) saying "this is the future everybody get it", and usually being the next to last to implement it.

 

[Analog Kid]

1) US 5G C-band operates in frequency ranges close to those used by the Radar Altimeters used by commercial airliners to determine how far above the ground they are. Other countries 5G services do not operate near these frequencies.

2) US 5G transmitters can operate at significantly higher power levels at peak than other countries. So their area of effect is much larger.

3) Some countries (like France) aim the transmitters towards the ground. The US aim them parallel to the ground to improve their effective area.

4) Some countries (like France) have have larger "buffer areas" around their major commercial airports so aircraft are higher off the ground so when added to smaller transmission areas and lower transmission power levels they are both less-susceptible to encountering interference and if they do, they are at higher altitudes and have more time to take corrective action.

5) It appears that no serious testing was performed by the FAA, the aviation OEMs (both aircraft and electronics) and the telecoms. So it sounds like the potential impact and seriousness of this issue was not seriously investigated until recently.

This all sounds plausible. Do you happen to have a reference on any of it? No hurry, it’ll take me some time to finish browsing the treasure trove linked by @asdfjkl; …

 

[Analog Kid]

This sounds like someone at the airlines trying to be relevant. We’ve heard this before when cell phones first came out. Planes were going to fall out of the sky if someone turned on their phone 🤦‍♂️

If what you took from the earlier debate on phones is that planes will fall from the sky, then I think you aren’t really comprehending the technical nuance…

 

[Analog Kid]

Ah yes because planes are dropping from the skies in the other countries that have been using C-band for a while now.

Which other countries? Which spectrum? What power levels?

 

[Dark_Omen]

This is why government regulators are a good thing and it’s a total lie that the “free market will optimize best societal decisions."

Government isn’t good for everything, even most things. But they do play a critical role in a decent, modern society.

Yeah, driving up prices or creating shortages and providing cruddy service is great!

 

[jhromeror]

Who owns the 5G C-Band? If it's AT&T and Verizon, why are the aviation companies even using gear that would be affected by its frequencies in the first place?

Edit: Article does state that the two carriers own it.

I highly recommend you look at Juan Brown´s video about the subject in BlancoLirio YT channel. The problem is mobile operators starting to use frequencies that are close to what airplanes and FAA have been using to measure the distance from the airplane to the ground. So, you don't really want to mess with such a critical component. That is why they are delaying this in the landing path for some airports.

 

[casimir83]

Just a reminder that these bands have been active in Europe near airports. Nothing has happened.

5G in Europe uses somewhat lower frequencies than 5G in US. The US frequencies for 5G are sufficiently close to those used by radio altimeters, potentially causing interference. The truth is that probably no one knows as of now it it's a danger or not. Since there are $$ billions involved, the attitude is going to be let's try and see what happens. Everyone can guess how many crashes will happen until changes are made. My guess is more than one.

 

[asdfjkl;]

The truth is that probably no one knows as of now it it's a danger or not.

Right on.

 

[jz0309]

This all sounds plausible. Do you happen to have a reference on any of it? No hurry, it’ll take me some time to finish browsing the treasure trove linked by @asdfjkl; …

What I read on another site is that in Europe the C-band operates up to 3.9GHz whereas in the US up to 3.98GHz which is closer to the altimeters in the aircrafts… I am still trying to find more technical details but it’s hard to find…

 

[asdfjkl;]

What I read on another site is that in Europe the C-band operates up to 3.9GHz whereas in the US up to 3.98GHz which is closer to the altimeters in the aircrafts… I am still trying to find more technical details but it’s hard to find…

Here's a diagram that shows the relationship between the two bands. This is taken from the RTCA doc I linked in a prior post.

 

[jz0309]

Here's a diagram that shows the relationship between the two bands. This is taken from the RTCA doc I linked in a prior post.
View attachment 1946290

Cool, thanks, missed your previous post…

 

[jz0309]

So this whole issue dates from October 2020 when the RTCA, an FAA advisory group, published a paper which showed that there could be interference between 5G base stations and phones and aircraft radio altimeters. This was based on experiments conducted in a lab.

Radio altimeters are used in a variety of aircraft to aid in landing and collision avoidance. This includes airliners and smaller aircraft like helicopters (e.g. air ambulances). For instance, some airliners can perform an "auto-land" (CAT III landing) when weather conditions are particularly bad. Basically cockpit automation will bring the aircraft very very close to the runway.

The cell industry responded to this with a white paper that basically said, "Bunk! We don't believe it." No testing or anything, just words. So while it is entirely possible that the lab results would not be replicated in the real world, how in the world could we allow for the possibility of mass casualties due to equipment malfunction caused by interference from 5G?

Radio altimeters have been in use for decades in aviation. Everything related to aviation is heavily regulated. Just creating "new" or "better" avionics would take years and cost $100Ms. Radio altimeters were here first. It is the responsibility of the 5G carriers to not interfere with existing technology.

For those that want all the gory details: Assessment of C-Band Mobile Telecommunications Interference Impact on Low Range Radar Altimeter Operations

Thanks for posting the link. The only piece where I probably differ from you is that the FCC probably has (or should have) the ownership of which spectrums are used or will be used. And while I am not an expert I do believe that it is the FCC that dropped the ball. But also there is a while consortium that defined 5G and the various spectrums, this has been in the works for many many years and it should have NEVER surfaced now….
But whoever dropped the ball, they need to do a proper root cause analysis and then consequences must occur.

 

[asdfjkl;]

From the RTCA report:

Note: Usage Category 1 aircraft refers to commercial airliners. Usage Category 2 aircraft refers to pretty much anything else that's not a helicopter. Usage Category 3 aircraft are pretty much helicopters. All of these aircraft would have redundant radio altimeters which is why the possible outcomes discussed below reference 2 altimeters.

Consistent with the parametric analysis results, the Usage Category 2 ITM is exceeded
throughout nearly the entire approach until the aircraft gets below 200 feet altitude. Even
for Usage Category 1, however, the results show significant impacts throughout the
approach with the potential for Catastrophic effects. All five base stations produce
interference above the safety margin relative to the Usage Category 1 ITM, and two of the
five base stations even breach the ITM itself. It should also be noted that the computed
interference levels from all five base stations significantly exceed the Rec. ITU-R M.2059
Receiver Overload protection criterion of -73 dBm/MHz (based on the -53 dBm limit given
in Table 6-1 and an assumed signal bandwidth of 100 MHz).

The interference seen throughout the CAT II/III approach scenario is likely to cause many
of the operational impacts noted in Table 5-1 which are applicable to approach and landing
(or to all phases of flight). However, the most concerning result shown in Figure 10-33 is
the large interference spike (more than 7 dB above the Usage Category 1 ITM) seen at an
altitude of about 275 feet. Since the radar altimeter antennas in a multiplex installation are
typically adjacent to each other, it is anticipated that such an interference spike would result
in a common-mode failure of all radar altimeters on the aircraft. Considering a dual radar
altimeter installation, which is the most common on Usage Category 1 aircraft, the
following outcomes are possible:

1. Both radar altimeters become inoperative (either reporting NCD or indicating a
hardware failure);

2. One radar altimeter becomes inoperative, while the other radar altimeter provides
erroneous altitude readings;

3. Both radar altimeters provide erroneous altitude readings which do not agree; or

4. Both radar altimeters provide erroneous altitude readings which are in agreement.

In the first case, it is expected that the autoland function will disengage, and the flight crew
will need to intervene to determine whether the aircraft can be landed safely or if they must
execute a missed approach or go-around. Such a determination must be made very quickly,
and using limited information. For a typical Usage Category 1 aircraft, the interference
event at 275 feet AGL leaves as little as 20 seconds before touchdown if the approach is
continued. Further, in a CAT II/III approach the pilots will have little or no visibility along
the runway to identify visual cues to assist in their determination of the actual height above
ground. Even if the pilots are able to react in time and execute a missed approach, this
maneuver poses a significant safety risk to both the landing aircraft and other air traffic in
the immediate area, particularly in low-visibility conditions. This places additional burden
on air traffic controllers to safely manage the airspace. In addition, if multiple landing
aircraft are impacted by RF interference and must execute missed approaches in low
visibility conditions with high volume air traffic, controllers may need to stop issuing
approach clearances to the specific runway or airport that is affected.

In the second case, the availability of only one radar altimeter means that the erroneous
readings from the second altimeter cannot be identified as such by either the autopilot
system or the flight crew. On some Usage Category 1 aircraft, this situation may not result
in the pilots being alerted to abort the landing, and they must make their own determination
on whether the approach can be safely continued. As in the first case, this determination
must be made very quickly, and with limited information. If the approach is continued in
this scenario, the erroneous altitude readings will likely cause the flight crew to conduct
the landing flare and throttle retard either too early or too late. At best, this would lead to
a hard landing, and at worst, a Catastrophic impact with the ground would occur.

In the third case, it is expected that the autopilot system will be able to identify the
mis-comparison of the radar altimeter readings and conclude that the data is erroneous. This
scenario will then typically lead to the same result as the first case. However, on some
aircraft types the erroneous readings from one altimeter may be continued to be used by
the autopilot system unless there is flight crew intervention in response to the
mis-comparison. In this instance, if the pilots do not respond in time, the result may be a
Catastrophic impact with the ground due to improper timing of the automated flare
maneuver and auto-throttle retard. Such was the case for the Turkish Airlines flight 1951
crash near Schiphol Airport in Amsterdam on February 25, 2009 [43].

The fourth case presents the greatest danger. If both radar altimeters are erroneous but in
agreement, then neither the autopilot system nor the flight crew will be able to identify this
situation, and the approach will proceed with incorrect altitude readings. This will lead to
the autoland system executing the flare maneuver and autothrottle retard at the incorrect
time, causing either direct Catastrophic impact with the ground, or causing the aircraft to
stall and subsequently have a Catastrophic impact with the ground. In this instance, the
pilots will be unaware of the erroneous data and unable to intervene.

In all cases, possibility of harmful interference in this instrument approach scenario is
particularly dangerous given that up to the present time, radar altimeter failures during this
phase of flight have been extremely uncommon, especially on Usage Category 1 aircraft.
Based on a typical descent rate of 600 to 800 feet per minute.

Thus, the occurrence of such failures is certain to cause confusion among the flight crew
which could further complicate and delay their response.

 

[Analog Kid]

Cool, thanks, missed your previous post…

I’m a long way from absorbing all the implications and checking any biases, but there’s a lot to learn on the fundamentals in that document.

I’m looking for a table of what bands are used in which countries. All of the points @CWallace mentions would be important mitigations. Another 100MHz would certainly help. Antenna patterns would help too— the worst case scenarios in @asdfjkl; ’s document look to be the bands directed toward higher elevation angles.

 

[Glideslope]

What I read on another site is that in Europe the C-band operates up to 3.9GHz whereas in the US up to 3.98GHz which is closer to the altimeters in the aircrafts… I am still trying to find more technical details but it’s hard to find…

This is correct. In the US the issues are with AT&T and Verizon. T-Mobile is not as close to the mm wave frequency of the Radar (Radio) Altimeter used in Auto Land Cat 2 and Cat 3 landings. Prior to AT&T and Verizon backing down today NOTAMS were going out to flight crews not allowing Cat 2 and Cat 3 approaches and a host of other procedures requiring the Radio Altimeter at 80 airports in the US where this would be an issue (C Band Frequency towers within 2 miles if the ILS Transmitter.)

The RTCA Commission warned of this back in November 2021. The FAA took no action until public pressure forced them to release an AD in December. If they had not backed off as of 5 Zulu today hundreds upon hundreds of flights would have been canceled going into one of these 80 airports if they had less then 1/2 mile Cat 1 ILS visibility. Complete chaos.

The EU handles this situation far better. The FAA is an embarrassment to be honest, IMO. Very glad I’m retired these days.

 

[Analog Kid]

Thanks for posting the link. The only piece where I probably differ from you is that the FCC probably has (or should have) the ownership of which spectrums are used or will be used. And while I am not an expert I do believe that it is the FCC that dropped the ball. But also there is a while consortium that defined 5G and the various spectrums, this has been in the works for many many years and it should have NEVER surfaced now….
But whoever dropped the ball, they need to do a proper root cause analysis and then consequences must occur.

Not sure what happened exactly, but I’d guess the FCC is under pressure to add spectrum so ever more people can watch ever more cat videos at ever higher resolution. Their solution has been to start eroding the guard bands between critical spectrum bands. If you look at @asdfjkl; ’s spectrum plot, the radar band is 200MHz from the 5G band. At 4GHz that is a pretty sharp band edge. Someone probably made the determination that forcing modernization of the receive filters is a reasonable price for 280MHz of better cat videos. It might be technically solvable (I haven’t gotten to mitigations in the document yet), but even so it will take time to deploy.

The FCC tends to regulate emitters, because those are the devices that impact their surroundings, and leave it to receiver makers to design to their environment. The problem is in situations like this where the environment changes after the design has been deployed into critical infrastructure. That spectrum used to be used for satellite downlinks, so nobody worried about it reaching earth with power sufficient to upset aircraft radar— the filters deployed were sufficient. Now the FCC says it can be used for terrestrial broadcast at the airports’ edge with directional antennas— and those filters look woefully inadequate.

My understanding is that the EU has started regulating receivers as well as transmitters, trying to ensure that receivers aren’t susceptible to out of band emissions. It makes it a lot harder to build cost effective receivers, but it’s probably meant to anticipate and avoid this kind of situation in the future.

 

[WiseAJ]

Just call it 6G and it will be fine. Wouldn’t be the first time AT&T lies about what cellular technology their signal is.

 

[binaryfuneral]

(cue whiny Gen Z/Millennial voice)
Cancelled flights and plane crashes are a small price to pay if I get faster Instagram notifications and TikTok uploads. Defund the FAA!

Not.

Ok boomer.

 

[binaryfuneral]

This is one of the consequences of the U.S. trying to push mmWave, just to be different and to go against global efforts. China had focused and deployed mid-band 5G equipment all around the world. Americans basically tried to reinvent the wheel against the laws of physics.

The U.S. finally admitted mid-band 5G is needed for mainstream users, but none of the preparation work had been done by FCC and FAA.

lol okay comrade

 

[E.Lizardo]

**** the airlines.

See comment #5

 

[Lihp8270]

(cue whiny Gen Z/Millennial voice)
Cancelled flights and plane crashes are a small price to pay if I get faster Instagram notifications and TikTok uploads. Defund the FAA!

Not.

Ok boomer

 

[scupking]

Why didn’t they just stick with 4g and improve coverage… 4g can already reach speeds faster then most home internet..

 

[CWallace]

This all sounds plausible. Do you happen to have a reference on any of it? No hurry, it’ll take me some time to finish browsing the treasure trove linked by @asdfjkl; …

5G and Aviation Safety | Federal Aviation Administration

The FAA, collaborating with the aviation sector and wireless providers, has completed work to ensure that radio signals from newly activated wireless telecommunications systems can coexist safely with flight operations in the United States until at least January 1, 2028. Voluntary mitigations by...

www.faa.gov

 

[Devin Breeding]

Which other countries? Which spectrum? What power levels?

Read his previous post as Sarcasm