FAA Grants TSO Approval Of ‘5G Tolerant’ Radalts

Terrain series RA-5500 radar altimeter
Terrain series RA-5500 radar altimeter.
Credit: FreeFlight Systems

Avionics manufacturer FreeFlight Systems announced that its “5G tolerant” Terrain-series radar altimeters have received FAA design and production approval.

The FAA technical standard order (TSO) authorization, effective Aug. 8, certifies that FreeFlight Systems’ new-generation RA-5500 and RA-6500 radar altimeters (radalts) meet the performance standards required for airborne low-range radar altimeters and can now be manufactured. The RA-5500 is designed for small airplanes and helicopters certified under FAA Parts 23 and 27 regulations. The RA-6500 is designed for transport-category airplanes and helicopters certified under Parts 25 and 29 that require dual radalts.

Irving, Texas-based FreeFlight Systems launched development of the Terrain-series systems in 2019 in anticipation of a potential clash between existing radalts, which operate in the C-band at 4200-4400 MHz, with new 5G wireless telecommunications networks operating at nearby frequencies. Radalts track an aircraft’s clearance height over terrain by measuring reflected signals from 2,500 ft. above ground level; the data they generate is used in terrain awareness warning systems, TCAS, flight-control, autoland and other systems.

FreeFlight Systems said it has completed major certification milestones since October 2021 while working toward the TSO authorization, including successful flight and FAA alternative means of compliance testing. “The Terrain series demonstrated that 5G interference rejection enables users to operate aircraft safely, even in close proximity to 5G cellular towers,” the company said Aug. 16.

The RA-5500/6500 units offer up to a 60% reduction in volume compared to currently fielded radalts and were designed to simplify retrofit installations by supporting existing antennas, control heads and cabling, FreeFlight Systems said. The Terrain series incorporates the latest ethernet connectivity standards for new avionics platforms while retaining an analog ARINC 552 interface for integration with legacy indicators and components.

“We have a considerable backlog of orders from operators and OEMs, particularly the advanced air mobility segment,” FreeFlight Systems President Anthony Rios said. “Now having the TSO certification, we are ready to begin product shipments. This is good timing considering the accelerating deployment of 5G networks across the country which continues to challenge flight safety.”

Bill Carey

Based in Washington, D.C., Bill covers business aviation and advanced air mobility for Aviation Week Network. A former newspaper reporter, he has also covered the airline industry, military aviation, commercial space and unmanned aircraft systems. He is the author of 'Enter The Drones, The FAA and UAVs in America,' published in 2016.