Emirates president: The 5G snafu is the biggest screwup witnessed in my career | Hacker News Reader

Emirates president: The 5G snafu is the biggest screwup witnessed in my career

cnn.com

38 pointsDiesel55525 comments

Big picture in bad weather certain aircraft that relied on their radar altimeter to help guide them to the runway cannot do so at certain locations.

http://www.alpa.org/resources/aircraft-operations-radar-alti...

> When operating in U.S. airspace, the following operations requiring radio altimeter are prohibited in the presence of 5G C-Band wireless broadband interference

> Instrument Landing System (ILS) Instrument Approach Procedures (IAP) SA CAT I, SA CAT II, CAT II, and CAT III

Here is the S-ILS RWY 36 for DFW that requires SA CAT II. At the bottom you can see "RA 107/12" which means the airplane can fly down to 107' without seeing the runway. The 5G NOTAMS effect this approach.

https://resources.globalair.com/dtpp/globalair_06039I36LSAC2...

Here is the NOTAM for DFW affecting approaches.

> FDC 2/3758 (A0495/22) - IAP DALLAS-FORT WORTH INTL, DALLAS-FORT WORTH, TX. ILS RWY 17C (SA CAT I), AMDT 11B ... ILS RWY 17L (SA CAT I), AMDT 7 ... ILS RWY 18R (SA CAT I), AMDT 8A ... ILS RWY 35C (SA CAT I), AMDT 3 ... ILS RWY 35R (SA CAT I), AMDT 4B ... ILS RWY 13R (SA CAT I - II), AMDT 9B ... ILS RWY 17R (SA CAT I - II), AMDT 23D ... ILS RWY 18L (SA CAT I - II), AMDT 3 ... ILS RWY 31R (SA CAT I - II), AMDT 15 ... ILS RWY 17C (CAT II - III), AMDT 11B ... ILS RWY 17L (CAT II - III), AMDT 7 ... ILS RWY 18R (CAT II - III), AMDT 8A ... ILS RWY 35C (CAT II - III), AMDT 3 ... ILS RWY 35R (CAT II - III), AMDT 4B ... ILS RWY 36L (SA CAT II), AMDT 4 ... 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. 19 JAN 05:00 2022 UNTIL 19 JAN 05:04 2024 ESTIMATED. CREATED: 13 JAN 05:05 2022

I’ve been researching this: original idea is that the 5G signals are “de-sensing” the Instrument Landing Systems (ILS) on airplanes that receive the radar signals from the airport.

The 5G C-band is 3.7-3.98GHz; The global aeronautical band is 4.2-4.4GHz where supposedly the modern ILS reside..

Of course the planes could be fitted with better instruments with filtering that do not desense from a signal 200MHz(!) away.

I did not find much info on 4GHz ILS so I’m not sure how widespread it is used in airports. Seems that the 110MHz/330MHz system is prelevant. (Which I don’t belive could be affected)

What I’m more interested is the quote from the article: “… compromise not only the radio altimeter systems but the flight control systems on the fly by wire aircraft.”

Does anyone have a guess what fly by wire systems could be affected by those 5G band signals?

This isn’t the ILS signal, it’s the radar altimeter.

Equally crucial.

These same C-band 5G frequencies are used in France (and 39 other countries).

There are no known interference issues.

Everything works fine, every day, for thousands of flights.

Except at half power directed away from the air. Quoteddirectly from the article:

"We were not aware that the power of the antennas in the United States have been doubled compared to what's going on elsewhere. We were not aware that the antenna themselves have been put into a vertical position rather than a slight slanting position, which then taken together compromise not only the radio altimeter systems but the flight control systems on the fly by wire aircraft."

There are three categories of ILS. The most basic one can get you down to 200' AGL and can be flown using only the signals from the localizer and glideslope antennas. These are the 110 and 330 MHz systems, respectively. They are transmitters sited at the airport, and there is receiving equipment in the aircraft. The aircraft uses a standard barometric altimeter. (Technically a "sensitive" altimeter but this distinction is pretty much irrelevant if you're flying anything made after 1930.) No radar altimetry or other special equipment is required; small single-engine planes flown by appropriately rated private pilots fly these all the time. These systems aren't affected by 5G.

The other two categories get you down to 100' AGL and 0' AGL, and these are the ones at issue. These require additional equipment, training, operations manuals, and certification of air crew. They also use the localizer and glideslope, but they require a radar altimeter as well (plus a bunch of other additional equipment in the aircraft, mostly for redundancy, that isn't relevant to this discussion). The radar altimeter is C Band and has no ground components.

The 0' AGL category is full autoland, with the autopilots controlling the aircraft not just all the way down to the ground, but throughout the landing rollout too. I suspect these are the "fly by wire" systems people are referring to, which is a bit of a misnomer if that's the case. "Fly by wire" is when the stick/yoke has no mechanical-hydraulic connection to the flight control surfaces; instead it provides signals to a set of flight computers, which mix those inputs with signals from the aircraft's sensors to produce an output for the actuators. It's possible that the radar altimeters are included in the inputs to the flight computers but I don't know. (I'd be surprised.) Autopilots, on the other hand, are more properly referred to as "automation." These would definitely be affected by problems with the radar altimeters during Cat II & III ILS approaches.

Edit: Some Cat I (basic) ILS approaches are marked "SA" meaning "Special Authorization." These approaches do require radar altimetry, but they're the exception when it comes to Cat I.

This is why I included my initial post on this topic. The 5G band affects the Radar Altimeter. The flight control systems rely on many inputs. If one of those inputs is the Radar Altimeter than the issue with RA could translate to an effect on the flight control system. This is well recognized and hence why the approaches (the way airplanes get close to runways in bad weather) that use this system are unavailable via NOTAMs.

I wonder if there are any other unforeseen consequences to blanketing the world in high frequency transceivers.

Wow there careful friend, you wouldn't want to be labeled as one of those 5g conspiracy nuts would you?

Better not to ask questions and just trust the experts.

"We are frustrated by the FAA's inability to do what nearly 40 countries have done, which is to safely deploy 5G technology without disrupting aviation services, and we urge it do so in a timely manner,""

What have the other countries done differently?

Their equivalent FCC bodies limited the power gain on the antennas and made them have slanted downward facing beams.

The better question to ask is why is the FCC selling spectrum that is actually already in use by aeronautical instruments?

Narrator: the answer $$$

Do the FCC and FAA just not talk to each other? How was this missed?

It seems like yet another inability to settle on a sensible solution due to holding corporate constructs sacrosanct. Ma Bell "bought" some colors of light, making the FCC unwilling to tell them to hold off to avoid interfering with existing infrastructure, so it was left to the FAA to pick up the pieces. Then the mitigating actions of the FAA will be characterized as "incompetent government" when the real problem was corporate corruption at the FCC.

Step 1: Defund and castrate the government. To hell with administrative state!

Step 2: Observe disaster.

Step 3: Bitch and moan about how the ineffectual government was not able to prevent this. Offer the solution of ... small government.

GOTO 1.

That would be government small enough to fit into a woman’s vagina, right?

The same reason they allowed Boeing MAX with the MCAS (May Crash Any Second) to fly.

If only there was someone who Presided over all these agencies, and could fix this. /s

Of course in the real world, the utterly stupid decision to sell colors of radio waves instead of just regulating their use has this predictable result.

I just finished "Flying Blind", describing how the Boeing engineering and oversight culture was destroyed, and I know how. These agencies have been gutted and corrupted and are no longer there to regulate. They are there to facilitate shareholder value. They are supposed to protect the public good on our tax dime, but we are not the customers - the CEO and the nebulous shareholder is the customer.

Interagency cooperation is a well documented issue in our current government. However, this discussion has clearly occurred for years if you look at the documentation. Simply, nothing was done to resolve the issue until the true effects came to bear. People realized there was an issue. Both sides saw the issue. Both sides issued documentation. Both sides did nothing until the issue actually happened. Then they freaked out. I blame the FAA for this one. They should have raised their concerns publicly much earlier. I have worked with the FAA a bit, I have not been impressed.

How were plane manufacturers allowed to use spectrum licensed by someone else in the first place?

The radar altimeters came first, so the FCC should never have been allowed to sell that spectrum or allow the power levels it did.

It’s not like they could reasonably use other frequencies: Those in use for radar altimeters are defined by the physics of radar signals and this band offers the best, safest, most accurate results which is crucial when landing massive airliners full of people.

Every other country in the world has solved this by limiting 5G spectrum sales to below the bands used for radar altimeters, limiting power output, having restrictions around airports, and mandating things like downward-angled antennas.

Blame the FCC for this, not the FAA and the plane manufacturers.

There's a 200 MHz guard band between, and (on top of that!) another 200 MHz unused. The altimeters aren't even close to the 5G spectrum. The gap between C-band 5G and the aircraft frequencies is ENORMOUS, wider than anywhere in the world.

It’s not that simple. Radar altimeters use very low power levels and are extremely sensitive to both adjacent channel and out of band interference. Until now this has not been an issue because systems operating in the 3.8-4GHz range have had low power levels.

When you’re pumping that much RF energy out, 200MHz separation isn’t nearly enough. Especially as many aircraft have been flying for decades and frequency filtering standards for radar altimeters against this level of interference weren’t a design requirement in the past.

The RTCA did a comprehensive study on this and found substantial interference of radar altimeters from 5G networks at the intended power levels would result. Given that RAs are the only mechanism by which an aircraft can reliably know its height above the ground on take off and landing, this is a crucial safety issue. https://www.rtca.org/wp-content/uploads/2020/10/SC-239-5G-In...

Again, there’s a reason that every single country other than the US that’s approved 5G spectrum has avoided this issue by insisting on lower power levels, frequencies further apart, larger frequency gaps, and buffer zones around airports.

Can someone explain, why does it matter if the antennas are upright or slanting?

Upright antennas will yield higher coverage with less antenas.

Slanted antennas will limit the amount of non useful RF escaping upwards into airplanes' radomes but will have a range limited by the slanting + beamforming angles.

An analogy is having public lighting with the bulb focused horizontally versus focused downwards. If it is facing horizontally the light will illuminate farther but a fraction of the light will be light pollution pointed at the night sky. If the light is facing downwards it will be limited by the aperture of the lamp post holder.

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