5G vs. Planes: FAA Orders Filters to Stop Altitude Confusion Chaos
Published Date: 3/21/2025
Rule
Summary
If you fly or work with certain MHI RJ Aviation ULC regional jets, heads up! The FAA found that 5G signals can mess with the planes' radio altimeters, which help pilots know how high they are. Starting April 25, 2025, these planes must get a special filter installed to block 5G interference and keep flights safe. This fix helps avoid costly problems and keeps everyone flying smooth and sound.
Analyzed Economic Effects
3 provisions identified: 1 benefits, 2 costs, 0 mixed.
Mandatory RF filter installation for listed MHI RJ jets
If you operate any of the listed MHI RJ Aviation ULC regional jets, you must install a radio frequency (RF) bandpass filter on the coaxial line between the radio altimeter and the receive antenna by the deadlines in this AD. The rule applies to specific models and serial number ranges (for example, CL-600-2B19 S/N 7002–8113, CL-600-2E25 S/N 19013–19990) and is effective April 25, 2025. For airplanes with dual radio altimeters, you may alternatively install the filter on one altimeter and deactivate the second as described in the service bulletins.
Safety fix to prevent 5G C-Band interference with radio altimeters
This rule addresses 5G C-Band (3.7–3.98 GHz) interference with radio altimeters that can inhibit certain failure messages and aural alerts. The AD requires the RF bandpass filter to prevent radio altimeter anomalies that could otherwise lead to ignition hazards from overheated hydraulic fluid or wing leading-edge deformation, which may affect continued safe flight and landing.
Model-specific compliance deadlines and alternatives
Different airplane models have specific compliance windows: CL-600-2B19 airplanes must install the RF filter within 2,300 flight hours or 12 months after April 25, 2025 (whichever comes first); CL-600-2C10, CL-600-2C11, CL-600-2D15, and CL-600-2D24 airplanes must install within 2,100 flight hours or 12 months after April 25, 2025; and CL-600-2E25 airplanes must install the RF filter before the next flight in the contiguous U.S. airspace after April 25, 2025. The AD also provides conditional credit for prior installations using listed service bulletins or engineering orders.
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Key Dates
Department and Agencies
Related Federal Register Documents
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