Radio (Radar) Altimeter 5G Interference Airworthiness Directive (AD) Compliance – Does This Apply to Me?

The FAA has identified 5G radio altimeter interference safety concerns and published airworthiness directives (AD) for both airplanes and rotorcraft. The ADs require changes to flight manuals and prohibit certain operations until radio altimeters are modified to meet tolerances. 

NOTE: Garmin DOES NOT recommend updating radio altimeters for aircraft not impacted by the ADs as the FAA anticipates making new rules, with new requirements, for radio altimeters in the future.

Does AD 2023-10-02 Affect my Airplane?

• Any aircraft with a GRA 5500 or GRA 55 cannot perform certain low-visibility landing operations (shown below) at any airport unless they have upgraded to become a radio altimeter tolerant airplane. Airplanes without the appropriate upgrades will be able to operate into any airport but cannot fly the prohibited low-visibility operations.

• The above entry must be placed in the Aircraft Flight Manual until the aircraft is modified to a radar tolerant airplane.
• For an airplane to continue to operate under 14 CFR Part 121 on or after February 1, 2024, it must be modified to be a radio altimeter tolerant airplane.

Does AD 2023-11-07 affect my Rotorcraft?

• Any rotorcraft with a GRA 5500 or GRA 55 cannot perform certain operations (shown below) unless they have upgraded to become a radio altimeter tolerant rotorcraft. Rotorcraft without the appropriate upgrades will be able to operate but cannot fly the prohibited operations.

• The above entry must be placed in the Rotorcraft Flight Manual until the aircraft is modified to a radar tolerant rotorcraft.

Garmin has developed a solution for the GRA 5500 and GRA 55 radio altimeters called the GRA 5500/55 External Filter.  The GRA 5500/55 External Filter is TSO approved and accepted by the FAA for use by aircraft installers to eliminate aircraft operational limitations published in FAA AD 2023-10-02 for Part 25 and Part 23 Class IV aircraft, and AD 2023-11-07 for Part 27 and Part 29 rotorcraft.  The GRA 5500/55 External Filter is available for purchase and installation today.

Installation of the GRA 5500/55 External Filter with the GRA 5500 or GRA 55 radio altimeters also allows compliance to be shown to corresponding radio altimeter 5G interference Airworthiness Directives issued by TCCA in Canada and ANAC in Brazil.  Applicability of these ADs is similar to those issued by the FAA.  Please contact Garmin for more information.

Garmin is also a lead member of the RTCA Special Committee (SC-239) that is developing new standards for future radio altimeters, which will include ultimate 5G mitigation requirements.