A meaningful slice of the U.S. business jet and airline fleet is about to lose some options for getting into Canada in bad weather. A new FAA airworthiness directive (AD), effective July 1, applies to U.S. registered aircraft and bars any that haven’t proven they can handle 5G interference from flying the lowest-visibility approaches and automated landings once they’re in Canadian airspace. Transport Canada has spent the past few years protecting that airspace with exclusion and protection zones, plus power restrictions, which kept interference at bay. Those 5G exclusion zone protections come down July 1, and non-tolerant aircraft lose the cushion that let them operate there. The AD reports that radio altimeters have been experiencing interference from wireless broadband operations in the 3.7-3.98 GHz frequency band, the 5G Lower C-Band, while flying in Canadian airspace. That interference makes them unreliable. The radio altimeter measures the vertical distance between an aircraft and the ground beneath it, making it a critical safety tool. For non-radio altimeter tolerant aircraft, that interference is what triggers new restrictions on flying and landing in Canadian airspace, not a blanket grounding, but specific limits on the operations that depend most on precise altimeter data. A radio altimeter tolerant airplane is one whose installed altimeter has been shown, through an FAA-approved method, to keep working through 5G interference. Non-tolerant aircraft haven’t been shown to meet that standard. The FAA has required that non-radio altimeter tolerant aircraft revise the existing AFM to incorporate limitations before flying in Canadian airspace. This follows the 2021 and 2023 U.S. 5G ADs. These limitations prohibit: Instrument Landing System (ILS) Instrument Approach Procedures (IAP) special authorization (SA) category (CAT) I, SA CAT II, CAT II, and CAT III Automatic Landing operations Manual Flight Control Guidance System operations to landing/head-up display (HUD) to touchdown operation Use of Enhanced Flight Vision System (EFVS) to touchdown under 14 CFR 91.176(a) The FAA also requires that commercial aircraft operating under Part 121 in Canadian airspace be modified from a non-radio altimeter tolerant airplane to a radio altimeter tolerant airplane. Commercial owners and operators will need to decide if living with these limitations is worth skipping the retrofit, since it’s only relevant when flying low-visibility approaches into Canada. Completely replacing the radio altimeter is expected to cost up to $120,000, while adding a filter to make it tolerant runs up to $14,040. In contrast, revising the AFM is only expected to cost $85. The rule itself is final, but Transport Canada has reserved the rights for a sequel to this story as it is still deciding whether to add further operational restrictions. Confirming an aircraft’s tolerance status now won’t necessarily lock in certainty, but it’s the cheapest way for owners to stay ahead of whatever Transport Canada decides next.
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