5G-Mitigating FreeFlight Radar Altimeters Gain Approval

The RA-6000 dual-install and RA-5000 single-install digital TERRAIN models were certified as of August 8 to meet the performance standards required for airborne low-range radar altimeters.

Tuesday’s announcement comes in the wake of the launch by wireless carriers in January of this year to begin broadcasting in the 5G-C band to improve speeds of cellular networks. That launch triggered a scramble by the FAA and the telecommunications industry to find a solution to eliminate interference caused by 5G signals to aircraft avionics. Among the compromises established were limiting the power of the wireless transmissions and the creation of transmission-free buffer zones around busier airports.

Wireless carriers began discussing the use of the 5G-C band to improve network speed as far back as 2017. Broadcasting in this band near airports can disrupt radar altimeters aboard aircraft. Data supplied by radar altimeters gives pilots information about the aircraft altitude above terrain, and supplies information for several other systems aboard sophisticated aircraft used by airlines. If the information is suspect because of signal interference, especially in poor visibility, the aircraft cannot land.

“In 2019, foreseeing the interference to radar altimeters from C Band 5G telecommunications, we launched an innovative, clean-sheet radar altimeter design to provide protection from signal interference,” said Anthony Rios, president of FreeFlight Systems in a news release. “We are proud to have achieved TSO certification, which allows us to better serve our industry with a modernized, rugged, and flexible radar altimeter solution that currently does not exist in the market.”

Since October 2021, FreeFlight Systems has been completing major certification milestones, including successful flight and alternative method of compliance (AMOC) testing, while working toward receiving TSO certification.

According to FreeFlight Systems, the TERRAIN series radar altimeters are designed for all segments of aviation including general aviation, commercial transport, business aircraft, military, rotorcraft, and remote-pilot designs. The units enable the aircraft to operate safely, even in close proximity to 5G cellular towers.

The TERRAIN series’ altitude measurement range of up to 2,500 feet agl and 55,000 feet msl service ceiling comes in a small footprint design that can easily be installed in place of legacy radar altimeters from various manufacturers. To further support a wide range of aircraft platforms, the TERRAIN series incorporates the latest ethernet connectivity standards for new platforms while retaining an analog ARINC 552 interface for integration with legacy indicators and components. With existing installations in mind, the RA-5500 and RA-6500 simplify retrofit installations by supporting existing antennas, control heads, and cabling as needed. For additional display options, FreeFlight Systems offers the RAD45 standalone indicator which meets EASA AMC1 SPA.NVIS.110(b) guidelines.

“We have a considerable backlog of orders from operators and OEMs, particularly the advanced air mobility segment," noted Rios. "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.”