> The problem is that radio altimeters are pretty old, and their filtering technology is not great. So even though they are filtering the 3.7-3.98 GHz 5G band,

> The problem is that radio altimeters are pretty old, and their filtering technology is not great. So even though they are filtering the 3.7-3.98 GHz 5G band, it's not as effective as a modern RF system/filter would be. and actually not only are they old but they are defective - they were designed to function with guard bands half the size that the FCC ended up giving them, and they still are running into interference. They are basically picking up way way way more than they were originally specced to, and that's suddenly a problem because somebody moved in next door. also to my understanding it's specifically a problem with Boeing and other aircraft are much less affected. So we are also running into the "boeing has become a quasi-state enterprise that is too-big-to-fail and will be protected under all circumstances even when they do something obviously dangerous", like the MCAS system on the 737 MAX. honestly I kind of feel like the real situation here is that Boeing needs to issue an airworthiness directive and have those altimeters replaced. If a wing broke at half the loading spec, we wouldn't hesitate to say that's faulty and should be replaced. But with guard bands twice as wide as initially specced these altimeters are still having problems? Get them out of the air until Boeing fixes them. > The real concern should be the total lack of collaboration between the FAA and FCC. It's turning into a jurisdictional pissing contest. they were collaborating a long time ago - but again, there is only so much you can do when it suddenly turns out that a 2x margin of safety from the design spec (which itself incorporated a margin of safety) is not nearly enough. the spectrum was sold a long time ago. the airworthiness certificates were issued decades ago. At this point there is no solution possible that doesn't make somebody unhappy. I lean towards the party that needs to be made unhappy being Boeing here - but that will make airlines very unhappy as well. Saying "no you can't use that spectrum" is an unconstitutional taking at this point, you auctioned it off for cash monies and that absolutely puts a legally enforceable price tag as a minimum bound - in practice the value is higher since business plans have been built on it. But there is no constitutional right to fly a defective aircraft, if the FAA grounds your plane because it's unsafe that's not a taking. But that will have a massive impact on boeing, airlines, and the economy as a whole.