Re: ILS?
"Is that really the case? Every smartphone under the sun has supported simultaneous GPS, Galileo, GLONASS and BeiDou for donkeys years now, because the chips they use support all the systems together. Are avionics versions of the same tech that far behind?"
No and yes. Your phone might be able to do all four, but most phones do not. Lots of chipsets only do three of those, some are GPS/Glonass only, and the really cheap ones do AGPS which can use regular GPS but will take forever to actually get anywhere if that's all you have. In all cases, a lot of initial information comes from local towers before the location chip comes in for the fine details. The phones with all of those services enabled usually are the high-end ones or ones where the manufacturer got a nice supply contract. For context, while the iPhone 12 supports all four (plus QZSS), the iPhone 11, released about fifteen months ago, doesn't have BeiDou. Most won't have all four.
As for avionics equipment, it needs very thorough testing. Few make avionics equipment to use just one of the other services. Russia's is incomplete because they haven't replaced satellites. China's and Europe's are newer, at least in terms of whole-world coverage. Thus, if they're building it, they'll build it to use multiple services. The problem is that that equipment needs a lot of certification for safety, including the safety of all the code running on it. What will it do if GPS says one thing and Galileo says another? What if an entire satellite system can't be seen for some reason, either equipment fault or someone flipped a power switch? These situations need to have regulatory approval, meaning that they're only likely to get into new planes. There are lots of old planes that won't get retrofitted with that unless it becomes an issue of pressing safety concerns.
Biting the hand that feeds IT
