All barking up the wrong tree.

The FAA should have evaluated some actual altimeters before the FCC approved the use of C-Band for 5G and fed into that process.

This, coupled with the 737Max debacle - means heads really have to roll at the FAA. Problems with both attitude and competence.

Prior would have been challenging. The FAA was unusure how much spectrum to allocate to 5G. The band in question is 3.7 to 4.2 GHz. Prior to 2020 it was ALL used for fixed sattelite service (FSS). The FCC had a long negotiated process to determine how much or little or that would be reorganized to be used for mobile services (5G) and how much would remain as FSS. That dividing line would determine how far the new 5G c-band would be from the radio altimeter band. The FCC looked at reallocating as little as 100 MHz and as much as all 500 MHz to mobile services (although that was very unlikely). Boeing and the avionic companies simply said don't reallocate more than 400 MHz (5G would end at 4.1 GHz). The FCC reallocated even less. 300 MHz and then stripped off 20 MHz for a guard band so it ended at 3.98 GHz.

So while the FAA maybe could have done some preliminary testing of a few possible scenarios they didn't know the realignment plan until the FCC completed it. Still that happened in 2020 almost two years ago. At that point the FAA should have known that baring credible actual evidence of interference the auction and rollout would eventually happen. They could have mandated testing then or a year later when the auction was completed.

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