"On February 27, 2025, the FCC adopted a Notice of Inquiry, seeking comment on whether it should make... the Upper C-band (3.98-4.2 GHz) available for more intensive use [& how that] would impact radio altimeters, which operate in the adjacent 4.2-4.4 GHz band" - https://www.jdsupra.com/legalnews/what-s-new-in-wireless-march-2025-1941315/