Fifteen aviation associations including AOPA urged the Federal Communications Commission to suspend a Dec. 8 auction of spectrum in the 3.7–3.98 GHz band based on a study that found that some telecommunication services pose a “major risk” of interference with aircraft radar altimeter operations.
The chair of the House Committee on Transportation and Infrastructure, Rep. Peter DeFazio (D-Ore.), also called on the FCC to postpone the auction, citing aviation’s concerns.
In a Dec. 7 letter to the FCC, the aviation groups cited a study conducted by the technical standards organization RTCA that “revealed a major risk that 5G telecommunications systems in the 3.7–3.98 GHz band will cause harmful interference to radar altimeters on all types of civil aircraft — including large commercial transport airplanes; business, regional, and general aviation airplanes; and both transport and general aviation helicopters.”
An FCC licensee that gains access to the spectrum through the auction “may provide any services permitted under terrestrial fixed or mobile allocations” under FCC rules, according to an auction summary on the FCC's website.
However, results of the RTCA study “clearly indicate that this risk is widespread and has the potential for broad impacts to aviation operations in the United States, including the possibility of catastrophic failures leading to multiple fatalities, in the absence of appropriate mitigations,” the aviation groups wrote.
DeFazio, in a letter to FCC Chairman Ajit Pai, said the RTCA findings “not only align with earlier research identifying harmful effects of 5G networks to radio altimeters, but they reflect a clear need for the FCC to return to the drawing board with this premature plan.” Emphasizing the need for additional study, he noted that “we must never take a chance with aviation safety—and at no point should commercial interests be placed above it.”
In a separate submission to the FCC, the aviation industry offered a variety of potential mitigations to protect radar altimeters from interference from new 5G systems.
Future radar-altimeter technology might complement or supersede some recommended mitigations, they noted — and one way to accelerate deployment of radar altimeters designed to be tolerant of nearby 5G transmissions “would be for the 5G community, as new entrants to the band, to reimburse the affected manufacturers and flight operators in replacing their current radar altimeter systems, once new authorized equipment becomes available.” Specifics, however, were “beyond the scope of this filing.”
The request to suspend the FCC auction opens a new front for aviation in the resistance to 5G telecommunications’ uses of spectrum considered risky for radar-altimeter operation. On Nov. 17, in a letter to the bipartisan leadership of House and Senate committees with jurisdiction over transportation, AOPA and other aviation organizations noted the safety-of-flight concerns flagged by the RTCA study in urging the lawmakers to respond to the FCC’s imminent action to reallocate spectrum for uses including “5G applications by the telecommunications industry.”
