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Comment by tjohns | Hacker News Reader

This isn't a Boeing-specific issue. Boeing doesn't even make the avionics in question. Some of the manufacturers don't even exist anymore. It's not clear who would pay, or how you'd enforce it.

At the time these units were built, the filtering was sufficient to guard against the known adjacent users of the band (low-power satellite signals). Neither the FCC or the FAA set performance standards to suggest otherwise. Nobody expected at the time we'd be blasting high-power omnidirectional signals everywhere at 4 GHz - outside a few specialized uses, it's a terrible band for wide-area communication unless somebody is motivated enough to build tons of towers...which the cell companies suddenly are.

We can agree that the filters are garbage by modern standards, but they were considered adequate at the time the units were built based on the circumstances.

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> This isn't a Boeing-specific issue.

If Airbus has the same problem, then ground Airbus too.

> Boeing doesn't even make the avionics in question. Some of the manufacturers don't even exist anymore. It's not clear who would pay,

Surely when the parts break, they are fixed, and if they are not fixed, then the plane is either grounded or flies in conditions such that the equipment is not required. There is a somebody who repairs, services, or replaces broken parts. These parts are broken. So that somebody fixes it.

> or how you'd enforce it.

You'd enforce fixing this broken part the same way you'd enforce fixing any other broken part. When the FAA finally got around to deciding that MCAS was in fact broken, they grounded the 737 MAX until it was fixed.

Everybody's acting like it's not a big deal that this equipment can't handle a signal that is more than 220MHz away from their nominal operating frequency. Certainly if Hasbro wanted to sell Batman(TM) BatWalkie BatTalkies, but they were rendered inoperable by another signal that far from their operating frequency, the FCC would deny the device its operating license and it would be pulled from the market.

> Nobody expected at the time we'd be blasting high-power omnidirectional signals everywhere at 4 GHz

Infrastructure 5g antennas are directional. The mobile devices themselves are omnidirectional, but those are very low power devices.

It seems to me then the owners of the offending equipment are responsible for the bill. I don't see how you can come to any other logical conclusion.

At least I know why cell service at the airport is awful.

Nah, it's like healthy Western US forests need regular fires, but people moved into the woods, built flammable homes, and demanded all fires be stopped. Now we want to restart taking care of forests but they whine their house will burn. If avionics don't stick to their band, they are at fault.

> It seems to me then the owners of the offending equipment are responsible for the bill. I don't see how you can come to any other logical conclusion.

Because at the time the equipment was bought, it met every applicable federal standard. This would be unfair to the owners who had no way of knowing about the issue.

Also, in nearly every other case I can think of when spectrum changes, the FCC grandfathers in owners of legacy equipment.

> At least I know why cell service at the airport is awful.

I don't think that's at all related, given that we just started rolling out 5G. Plus the bands in question don't travel through walls very well. :/

At the time many buildings were sold, asbestos insulation met every applicable federal standard. The owners are still responsible for mitigating it.

> Because at the time the equipment was bought, it met every applicable federal standard. This would be unfair to the owners who had no way of knowing about the issue.

At least in Europe, there is precedent that modern use of frequency assignments make older equipment illegal to operate. 4G and 5G have heavily eaten into the frequencies used on stage for event equipment - microphones, IEM, that sort of thing. Many, many pieces can‘t be legally operated anymore, and it‘ll probably be the same in a few years time with the current-gen devices (although I hope I can swap crystals if needed and keep using my stuff).

Radio bandwidth is a scarce resource. If the radio altimeter is transmitting well outside of its boundaries and it creates problems (for any of the parties requirements), it’s the radio altimeters that need fixing. Even if it is expensive to do so.

No it did not meet every applicable law because it is using part of the spectrum it’s not supposed to be using. The only reason wireless communication in general isn’t pure jamming hell is because we abide by these simple rules.

I live 6 miles from an airport. I get less than 100kbps from Verizon on my iPhone 12. Thanks Boeing.

"Nobody expected at the time we'd be blasting high-power omnidirectional signals everywhere at 4 GHz - outside a few specialized uses, it's a terrible band..."

As I've point out in my post, why on earth wasn't all this sorted out before 5G was allocated the frequencies.

It seems to me that the the powers behind mobile services have railroaded themselves into these frequencies and that the FCC etc. haven't had the gumption to sort it out beforehand.

If 5G deployments broadcast too close to the frequency assigned to radio altimeters then that's something the FCC should have sorted out, but it appears more like the radio altimeters just have bad filters that let too much outside their assigned frequency through. That makes it a problem of the FAA. The FCC isn't responsible for policing bad receivers.

> That makes it a problem of the FAA. The FCC isn't responsible for policing bad receivers.

Ah, yes. The best thing you can have is tribal mentality in your government departments. Where instead of cooperating to sort problems out you just say "fuck everyone else" and press onward.

See my post above (once, I was on several pre-WARC/WRC advisory committees).

"That makes it a problem of the FAA. The FCC isn't responsible for policing bad receivers."

What do you mean by 'bad' receivers?

Spectrum management, irrespective of country, sets the parameters of every radiocommunication service by notional equipment standards - here that would be the typical intermodulation figures for radar receivers, inter alia.

The FCC and ITU through WARC/WRC - World Radiocommunication Conferences would have been aware of notional equipment standards for radar altimeters at the time the spectrum was allocated (equipment must comply with the standard or it be deemed out of spec - non compliant).

Note: adjacent services must consider interference to their adjacent services, etc. The standards associated with any service can only be deemed old or 'changed' at WRC conferences specifically to avoid the situation we now have here. The real question is 'who fucked up' - i.e.: did not abide by WRC rules (the international treaty/agreement obligations).

Remember, here international rules are paramount BECAUSE aircraft licensed in other countries that land on US territory also have to meet the same international standards for their radar altimeters as those of the US fleet - it has nothing to do with receivers being 'bad').

FYI: https://en.m.wikipedia.org/wiki/World_Radiocommunication_Con.... Note: the ITU deems that the FCC IS responsible for radio regulations within the USA.

Boeing would pay and the FAA as the enforcement agency would enforce it...

As mentioned, this isn't a Boeing-specific issue. This affects every major aircraft manufacturer, as well as a lot of smaller aircraft with aftermarket avionics. Surely Boeing isn't going to pay for the entire industry.

Also, the FAA has no way of knowing if a particular aircraft operator is using a radio altimeter or not. Even if I have one installed, maybe I chose to switch it off. It's also possible I'm using it for situational awareness only (which is still allowed) and not using it to descend below legal approach minimums.

Boeing pays for their upgrades. Airbus can pay for their upgrades. Douglas Aircraft pays for their upgrades after we revive the company.

Psst! Boeing isn't the only manufacturer affected.

"Airbus has issued Flight Operations Transmission 999.0002/22 (01/10/2022) which describes the currently understood effects of radar altimeter anomalies. Guidance is provided for A320 family, A330, and A340 aircraft for handing these anomalies.

"Embraer Flight Operations Letter 170-001/22 and Operational Bulletin 170-001/22 (01/02/2022): Describe the possible effects of C-Band 5G interference on its E170, E175, E190, and E195 aircraft.

"The FAA has developed a process by which better performing radar altimeters that are able to reject 5G interference can be approved to operate without regard to the AD and NOTAMs. These Alternate Methods of Compliance (AMOC) approvals will be specific to a combination of aircraft model and radar altimeter model. The method of approval will take into consideration the performance of the aircraft/radar altimeter combination, as well as the location and power of the 5G transmitter in the vicinity of the airport. Therefore, the AMOCs are being issued with a list of airports where they are effective. As of 1/25/2022, FAA has approved AMOCs for several models of radar altimeters, installed on Boeing 717, 737, 747, 757, 767, 777, 787, and MD-10/-11; Airbus A220, A300, A310, A319, A320, A321, A330, A340, A350, and A380, Embraer 120, 170, and 190, all Canadair CRJ aircraft, some DeHavilland Canada DHC-8, and some ATR aircraft. These AMOCs are limited to certain airports and specific models of radar altimeters. Pilots should ensure that they have AMOC documentation for their aircraft and airport (e.g. in a dispatch release) before operating at an airport without regard to the 5G AD/NOTAM."

https://www.alpa.org/resources/aircraft-operations-radar-alt...

So some altimeters, manufactured by companies supplying all OEMs way hefore 5g was thing, have trouble with 5G now. There seems to be a solution for this old equipment, civil aviation moves on. For once no need to pick on Boeing here. Or on anyone else.

I never said Boeing should pay for other companies upgrades. Maybe I could have said "the companies that own the airplanes"... but I'm not unaware that other companies are affected... that fact was even in the comment I replied too.

See my post about the ITU and international radio regulations.

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