The Civil Aviation Safety Authority announced this week that it would work with the Australian Communications and Media Authority (ACMA) and the aviation industry to ensure new 5G networks posed no threat to aviation.
New 5G frequency allocations will allow 5G networks to operate in the 3700-4000 MHz band, raising concerns about interference with radio altimeters, which use the 4200-4000 MHz range.
Aircraft use radio altimeters to accurately measure the height above terrain.
"Radio altimeters operate in the 4.2 – 4.4 GHz range and mid-band 5G transmissions have been introduced without issue in several jurisdictions," CASA says. "However, the introduction of 5G transmissions in 3.7 – 3.98 GHz range in the United States raised concerns about possible interference with radio altimeters, particularly during low altitude operations during take-off and landing near airports."
Australia will introduce a range of risk mitigations on new applications operating above 3700 MHz until 31 March 2026, which will be designed to protect against the risk of 5G interfering with radio altimeters and minimise disruptions to aviation.
"We do not expect to impose operational limits on air operators during this interim period," CASA states. "However, operators will need to upgrade radalts that do not meet minimum performance levels before the interim period ends.
"We will liaise with industry about the applicable performance standards for radalts and available options for upgrading."
The US Federal Aviation Administration already requires upgrades or replacement of radio altimeters that don't meet minimum performance standards.
"CASA is monitoring developments internationally as 5G is rolled out and we are confident the interim measures put in place by ACMA will ensure continued safe aviation operations.
Mitigation steps after 2026 will include a 200 MHz buffer between 5G wireless broadband and radio altimeter frequencies as well as limits on power and unwanted emissions.
WBB (wireless broadband) 5G services have been operating in Australia since late 2018, with the first commercial launches at the start of 2019. The first band in Australia for 5G was 3575-3700 MHz, in the mid-band. Before the launch of 5G, 4G services had been using this band since 2016.
In mid-2021, millimetre wave (mmWave) band 5G started to roll out in some areas, and in late 2021, spectrum licences were auctioned to support low-band 5G implementation.
ACMA has now started allocating spectrum suitable for 5G in the 3400-4000 GHz frequency range.