The FAA's latest action on radio altimeter upgrades marks another chapter in the multi-year effort to protect aircraft radio altimeters from potential interference generated by 5G C-band wireless transmissions. Since wireless carriers began deploying 5G service in the C-band spectrum (3.7-3.98 GHz)—frequencies adjacent to those used by radio altimeters—the FAA has worked through a series of Airworthiness Directives, Notices to Air Missions, and voluntary agreements with telecom operators to manage the risk of erroneous altitude data during critical phases of flight, particularly on approach and landing. The new deadlines set firm dates by which operators must retrofit or replace radio altimeters with units that have been demonstrated to tolerate C-band emissions, effectively ending the interim mitigations—power buffer zones, flight restrictions near certain airports, and NOTAM-based limitations—that have been in place since early 2022.
For working pilots, this matters because radio altimeters are safety-critical sensors feeding data not just to the altimeter display but to a wide array of downstream systems: autoland, terrain awareness and warning systems (TAWS), traffic collision avoidance (TCAS), autothrottle, windshear detection, and ground proximity warnings. Interference or erroneous data from these systems has historically triggered spurious warnings, uncommanded autothrottle or autopilot behavior, and in worst-case scenarios, unreliable altitude callouts precisely when crews need them most—inside the final approach segment down to touchdown. The interim restrictions imposed since 2022 already forced some carriers to cancel Category II/III approaches at certain airports during specific weather conditions, and unequipped aircraft faced dispatch limitations that complicated scheduling and crew planning. A hard compliance deadline removes ambiguity but places real cost and logistical pressure on operators still flying legacy altimeter equipment, particularly regional carriers, cargo operators, and business aviation fleets that may not have prioritized retrofit programs as aggressively as mainline carriers.
The broader significance of this deadline extends beyond any single fix—it reflects the FAA's ongoing struggle to keep pace with the collision between legacy avionics architecture and rapidly expanding commercial wireless spectrum use. The radio altimeter saga has become something of a case study in aviation/telecom coexistence, with the FAA, FCC, avionics manufacturers like Honeywell and Collins Aerospace, and wireless carriers like AT&T and Verizon negotiating buffer zones, power limits, and equipage timelines over several years. Similar spectrum-sharing tensions are likely to recur as 5G networks expand internationally and as future spectrum allocations (including potential 6G deployments) get evaluated for aviation compatibility. Operators should expect the FAA to continue leaning on firm compliance deadlines rather than indefinite interim mitigations going forward, signaling less tolerance for prolonged transition periods.
Practically, flight departments and maintenance planning teams need to treat this deadline as a fleet-wide compliance issue rather than a paperwork formality. Operators should confirm with their avionics shops and OEMs whether their installed radio altimeters are on the approved-compliant list, verify retrofit kit availability and installation lead times given potential supply chain bottlenecks, and factor retrofit downtime into maintenance scheduling well ahead of the deadline rather than waiting for a last-minute AD compliance crunch. Given the FAA's history of extending prior deadlines when industry-wide retrofit rates lagged, operators should nonetheless plan as though the newly announced dates are final, since continued delay creates operational risk exposure, insurance and liability questions, and the possibility of aircraft groundings or restricted approach authorizations at C-band-affected airports once the compliance window closes.