The FAA has required US operators, and foreign carriers flying to the United States, to equip aircraft with interference-tolerant radio altimeters. The rule covers an estimated 58500 units across roughly 40700 aircraft, with airline fleets required to comply by 30 December 2030 and other operators by 31 October 2034. The driver is the planned expansion of wireless services in spectrum adjacent to the radio-altimeter band, where 5G signals can corrupt the precise height-above-ground readings that pilots and automation systems rely on in the final stages of approach and landing. Radio altimeters feed terrain-awareness systems, autoland, and low-visibility procedures. An undetected error close to the ground is not a nuisance; it is a safety event.
India is not starting from zero. DGCA has already ordered that aircraft operating in Indian airspace must have radio altimeters tolerant of the country’s 5G C-band (3.3–3.67 GHz) by 31 December 2027 and has restricted certain automatic landing and enhanced-vision operations on non-tolerant aircraft until they are upgraded. That is a concrete step. The open questions are whether the current mandate fully matches the interference environment that will exist as 5G densifies around airports, whether airline upgrade programmes and budgets are on track for the full fleet-including lessors, regional and charter operators-and whether India is preparing for the next spectrum wave the way the FAA is preparing for Upper C-band.
Radio altimeters matter most when visibility is low and the aircraft is closest to the ground. India’s major airports sit inside dense urban and suburban spectrum environments. Airport-adjacent 5G, power levels, and antenna placement determine whether a tolerant altimeter is sufficient or whether operational restrictions will reappear as networks expand. Equipage rates, retrofit capacity, and the cost of new units will decide how many aircraft remain unrestricted for CAT II/III and autoland by the deadline. DGCA readiness is not only about publishing an order; it is about tracking compliance, coordinating with spectrum authorities, and ensuring that foreign operators into India meet the same standard without creating two classes of approach capability.
America’s 58,000-unit programme is a scale and cost story, billions of dollars, multi-year supply chains, and a hard date tied to spectrum auctions. India’s story is a readiness story. The regulator has set a 2027 tolerance deadline for the current C-band. The investigation that matters now is whether fleet data, airline capital plans, and spectrum-airport coordination are solid enough that the next expansion of mobile services does not force another round of operational limits or emergency retrofits. Radio altimeters are not optional avionics. If India does not already know the exact state of its fleet against both present and foreseeable interference, the 5G problem will not announce itself in a laboratory. It will announce itself on a low-visibility approach.