On 2022-06-05, at 22:01, Miles Fidelman <mfidel...@meetinghouse.net> wrote: > > Still doesn't address whether or not C band radios break radio altimeters.
The discussion reminds me of the early 1990s, when mobile phones became pocketable. There was some talk about how emissions from mobile phones that people take into cars could be bundled inside the car in unfortunate reflections and theoretically trigger airbag systems, hurt drivers and cause fatal accidents. We know how that went. (I got screamed at by taxi drivers more than once at the time while making phone calls in their cars. Needless to say, I didn’t manage to kill any of them.) Safety is about probabilities. A theoretical possibility that occurs 0.01 times during the lifetime of the universe would be reasonably recognized as safe. Of course, most people (including politicians) can’t compute (and don’t understand probabilities anyway), so we will see some technically unjustifiable compromises that will appease the uninformable public. By the way, the largest probability for influencing radio altimeter operation is likely to come not from the ground installations but from passengers using C-band-capable (3.x GHz 5G, e.g., band n77) devices on board… But addressing that would inconvenience the airlines, so it won’t be weaponized in the current attempt to squeeze 5G operators for money to replace crappy old altimeters that don’t work right with even a 220 MHz guard band. Grüße, Carsten
