The U.S. Federal Communications Commission (FCC) is requesting public comments on proposed changes to its spectrum rules that would accommodate future advanced air mobility operations, including everything from electric air taxi services to drones and autonomous cargo airplanes. 

Changes to the FCC’s spectrum regulations, which govern the allocation and licensing of frequencies used for wireless communications, would “support innovation, growth, and safety needs of this burgeoning sector as well as other uncrewed aircraft systems (UAS), such as drones,” the agency wrote in a statement on the notice of proposed rulemaking (NPRM), which it published online on January 17.

According to the FCC, wireless communications technologies on which the advanced air mobility (AAM) sector will depend include flight command and control for remotely piloted or autonomous aircraft, reliable in-aircraft broadband for passengers, and UAS detection technologies.

“Today, the Federal Communications Commission explores how our spectrum policies can support the continued growth of drone technology and the emergence of advanced air mobility, a new sector of the aviation industry that leverages new propulsion and flight control technologies to make passenger and cargo transportation more accessible, convenient, and efficient,” said FCC chairwoman Jessica Rosenworcel. “These technologies rely on spectrum for critical communications and navigation, so we are modernizing our rules to foster this innovation.”

The NPRM pertains to the use of three bands of the electromagnetic spectrum: 450 MHz, 24.45-24.65 GHz, and the 800 MHz commercial aviation air-ground systems band. 

Uncrewed Aircraft Communications

Proposed rules would open up the 450 MHz band to UAS networks for control and non-payload communications (CNPC). According to the FCC, the 450 MHz band comprises 650 kHz of spectrum designated for air-ground radiotelephone service (AGRAS) in general aviation aircraft. Current regulations confine the use of that spectrum to voice communications for aircraft traveling at high altitudes. 

Aura Network Systems, which has been building a wireless communications network for unpiloted and autonomous aircraft since 2021, is the only license holder occupying the 450 MHz general aviation ground band today. Until the FCC issues its final decision on the 450 MHz band, the Wireless Telecommunications Bureau will not be processing any applications for new licenses to conduct general aviation AGRAS operations in the 450 MHz band, the Commission noted. 

“While Aura has the authority to provide CNPC services today, the FCC’s [NPRM] is a crucial step toward achieving the regulatory clarity needed to accelerate transformative UAS technologies, supporting a wide range of applications from air-cargo logistics for both commercial and government markets to enhancing communications capabilities more broadly for the aviation community,” commented Aura CEO Kevin Steen. “This action is essential for fostering innovation and ensuring America’s continued leadership in global aviation.”

Radiolocation for Drone Surveillance

The FCC has also proposed using the 24.45-24.65 GHz band for radiolocation operations, enabling UAS detection systems. Existing regulations authorize the airborne use of that band for radionavigation, which is used in detect-and-avoid systems on board aircraft. Now the FCC wants to add ground-based radiolocation operations to that band as a secondary service enabling counter-UAS surveillance. It is seeking comments on the proposed amendment to 47 CFR Part 90 regulations on radiolocation services.  

Echodyne, which has developed a radar for both ground-based and airborne detect-and-avoid operations in the 24.45-24.65 GHz band, has been a proponent of this change since 2018, when it filed a petition to allow permanent radiolocation operations on that band. The FCC has granted limited waivers to Echodyne and MatrixSpace for such operations.

“We are in the middle of a revolution in the development and deployment of Uncrewed Aircraft Systems,” said FCC commissioner Geoffrey Starks. “This technology holds the potential to boost agricultural sustainability, speed up recovery from natural disasters, and support more efficient delivery of medicine, consumer goods, and more.”

“However,” he added, “we must also be clear-eyed about the threat that unauthorized UAS operations pose to public safety. Over several days in December, unsanctioned UAS operations over New York and New Jersey have caused significant confusion, threatened public safety, and even forced the closure of a major airport. As this episode demonstrates, while we continue to advance UAS technology, it’s imperative that we also support the growth of UAS detection and countersurveillance systems. I’m glad to see this NPRM support not just UAS operations but also technology to detect UAS systems when they’re being used to commit crimes or threaten public safety.”

Transmitter Power Restrictions

Lastly, the FCC aims to modernize Part 22 rules for commercial aviation air-ground systems operating in the 849-851 MHz and 894-896 MHz bands, which are used for inflight connectivity services. It has proposed an amendment to Section 22.867, which limits the transmitting power of ground and airborne stations. Current rules require that operational power limits be regulated by peak power. Now the FCC wants to use average power rather than peak power to determine those limits.

Gogo Business Aviation requested a waiver for rules in 2021 to accommodate its next-generation inflight connectivity system, arguing that the power limits would unnecessarily hinder the overall utility of the frequency band. After the FCC granted the waiver in 2022, Gogo filed a petition asking the Commission to modernize its rules.

In the NPRM, the FCC noted that updating those power rules would enable more efficient use of the spectrum and promote “technology neutrality,” meaning that the regulations do not favor or discriminate against any specific technology or platform. “Further, by amending these rules, we would harmonize commercial aviation air-ground systems power rules with other legacy service power rules, including PCS [personal communications service], AWS [advanced wireless service], and the cellular radiotelephone service,” the NPRM states.

The public comment period for the NPRM closes 30 days after publication in the Federal Register.