AvWeb is reporting that the rollout of 5G cell service has the potential to screw up the use of radar altimeters.
So what, you ask? You need a radar altimeter to execute really low-ceiling instrument approaches. Without a radar altimeter, the ability to shoot instrument approaches is basically going to revert to 1950s-era minimums. Which will mean more flights not making it through to destinations, more ground stops, and so on.