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