The Federal Aviation Administration (FAA) said it would issue a final rule on July 24, 2026, requiring all radio altimeters to meet new minimum interference-tolerance standards when the aircraft carrying them operate in the United States.
The agency published the statement on July 22, 2026, the same day the Federal Communications Commission (FCC) adopted its Report and Order setting rules for the auction of 160 MHz of Upper C-band spectrum between 3.98 and 4.14 GHz.
The commission voted to combine that block with the previously cleared Lower C-band to form a contiguous 440 MHz band, with the auction due to close by July 2027 and new wireless services permitted from December 2030 in the 75 largest US markets and July 2031 elsewhere.
Radio altimeters operate in the 4.2 to 4.4 GHz band, immediately above the spectrum being sold. They provide height-above-terrain data used for low-visibility takeoffs and landings and feed several safety systems, including terrain awareness and warning equipment.
Safeguards written into the FCC order
The FAA said the FCC order includes limits on the transmit power of the auctioned signals, a buffer band separating the new wireless allocation from the altimeter band, and height restrictions on transmission towers using the new spectrum. The agency said years of testing and technical analysis, coordinated with the FCC, support its conclusion that aviation can coexist with expanded wireless access.
In 2021, a dispute over the Lower C-band saw the FAA issue airworthiness directives restricting operations and negotiate buffer zones around 50 US airports with AT&T and Verizon.
Two deadlines and a rebate program
The final rule sets two compliance dates. The first applies to scheduled air carriers, which the FAA said must be able to keep operating without disruption in low-visibility conditions. The second, for all other aircraft, follows later. The agency did not specify the dates in its statement, though the January 2026 proposal tied the initial deadline to the FCC authorization date and gave other operators two additional years.
The FCC order also establishes a rebate program funded through auction proceeds to offset retrofit costs. In its notice of proposed rulemaking published on January 7, 2026, the FAA estimated that roughly 58,600 altimeters across some 40,900 aircraft would need replacement or upgrade, at an undiscounted cost of $4.49 billion. An industry coalition including the National Business Aviation Association told the agency in March 2026 that the real figure could exceed $7 billion.
The FAA said the incentives should bring next-generation equipment into commercial fleets several years earlier than would otherwise have been feasible.