The US Federal Aviation Administration (FAA) has signalled that it will require the operators of all 8,000 commercial aircraft to equip with either 5G C-Band-tolerant radio altimeters or approved filters by February 2024.

The agency is proposing the new altimeter standards in a 9 January regulatory filing, in response to 100 reports of potential 5G interference including faulty altimeter data, erroneous terrain and collision avoidance system warnings and incorrect landing gear alerts.


“As the flight crew becomes more desensitised to erroneous warnings, they are less likely to react to an accurate warning, negating the safety benefits of the warning altogether and likely leading to a catastrophic incident,” the proposal says.

In January 2022, US cellular companies AT&T and Verizon activated the first US 5G networks which use the 3700-3980 MHz radio range – close to the 4200-4400 MHz range used by radio altimeters. The agency warns that risks will increase as more US cellular companies launch 5G networks, and as they expand the bandwidth they use.

Those businesses initially voluntarily agreed to delay some C-Band 5G deployment until July 2023 while US airlines started to retrofit aircraft to ensure that they did not face interference. They were also prohibited from operating near 5G C-Band wireless transmitters unless specifically allowed, prompting airline chiefs to warn of an impending ‘catastrophic’ aviation crisis.

The FAA now says the 2024 mandate represents a longer-term solution that “will enable the wireless companies to achieve full use of their networks while maintaining aviation safety.”

The FAA says some altimeters ‘may already demonstrate tolerance to the 5G C-Band emissions without modification’, while others may need to be equipped with filters, or replaced,

Industry body Airlines for America (A4A) however warns supply chain trouble could compromise the ability to meet the deadline but said its members were working diligently to equip: ”Any government deadline must consider this reality,” it said.

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