The FAA doesn't cite that concern on their page, but having a 200MHz buffer in the US rather than a 380MHz buffer is a difference. As noted in the article you

The FAA doesn't cite that concern on their page, but having a 200MHz buffer in the US rather than a 380MHz buffer is a difference. As noted in the article you posted, Canada is requiring antenna down-tilting nationwide as well as exclusion zones around airports. EDIT: "an exclusion band is allowed ±10% around the band, within which the HIRF levels are very low—for radar altimeters, this spans 3.78–4.84 GHz" https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-Interference-Risk-to-Radar-Altimeters.pdf https://www.rtca.org/wp-content/uploads/2020/12/Slides-5G-In... So, in Europe, their C-Band ends at 3.8GHz and barely enters the range. In the US where we're going to 3.98GHz, we're well into that range. It looks like Korea's band ends at 3.7GHz which is outside the range (and definitely by 3.8GHz which is where band N78 ends; the US is using Band N77 which ends at 4.2GHz, but we've only licensed spectrum to 3.98GHz)