5G continues to be a problem, the FAA release a new SAIB

December 7 2021

The FAA started to worry about the rollout of 5G networks across the USA.

The new (not so new anymore) 5G antenna transmit at a very similar frequency (C-band) to aircraft radio altimeters. Radio Altimeters transmit on 4.2GHz to 4.4GHz, and 5G is 3.7GHz to 3.98GHz. Combined with the power setting they use and positions close to airports, this causes some concern.

The concern is interference. Interference means inaccuracies and sometimes total disruption and failure.

Various approaches, particularly low vis ones, rely on Radio Altimeter input – ILS, RNP (AR), Automatic landings, even HUD and EVFS stuff use them. So the FAA banned a whole load of approaches/operations at a whole load of airports.

January 2022

At least 100 airports had notams banning or restricting certain operations as the FAA worked to establish how big an issue it might be.

On January 19th much of the network had started to be switched on, but the rollout of services near major airports were delayed. The FAA brought in buffer zones at at least 50 airports.

They issued a bunch of Special Airworthiness Info Bulletins, Safety Alerts, and airworthiness directives. They also started allowing exemptions for certain aircraft types.

Later in 2022

A deal was done with the big5G service providers and they agreed to delay the switching on of antennas near the biggest of the big airports. This was due to expire on July 5th 2022 but was then extended to July 2023.

This FAA website has been pretty handy over the last year for checking who can do what, where.

July 2023 is coming around fast

That it is, which is why at the end of May 2023, the FAA released a new special airworthiness information bulletin (SAIB).

You can access the new SAIB AIR-21-18R3 (valid May 24th 2023) here.

WHAT DO YOU NEED TO KNOW?

• Operators must continue to voluntarily provide ‘specific information’ related to altimeter design, functionality and usage (in other words the FAA needs manufacturers and operators to assess the issue and is moving the burden to do so onto them)
• Previous Airworthiness Directives prohibiting certain types from certain operations remain in (come into) force from July 1st 2023 (so if you’re one of those types – which a lot of BizJets are – sorry)
• Part 121 operations will be banned from February 1st 2024 unless operations are performed in a ‘radio altimeter-tolerant’ airplane (the FAA are working on a technical standard order)
• Management of 5G C-band interference should be brought into your safety management systems, and flight planning
• Pilots should be reminded of the potential issues which could arise and be extra vigilant from July when more antenna will be turned on
• Additional crew procedures should be established if not already

References

The FAA 5G Aviation website is available here. This contains links to all current resources.

A good article from AIN on the current SAIB is available here.

A webinar posted by AIN Online (from EBACE 2023) discussing the impact of 5G interference, with a focus on Business Aviation aircraft.