FAA Issues Final Airworthiness Directive for Boeing 757 and 767 Over 5G C-Band Radio Altimeter Interference in Canadian Airspace

The Directive and What It Requires

The Federal Aviation Administration has adopted a final airworthiness directive (AD) — effective July 1, 2026 — applicable to all Boeing Company Model 757 airplanes and Model 767 airplanes. The directive requires operators to revise their existing airplane flight manual (AFM) to incorporate limitations that prohibit certain operations requiring radio altimeter data when the aircraft is operating in Canadian airspace. The FAA states it is issuing this AD to address an unsafe condition on these products.

The Safety Problem: 5G Lower C-Band Interference

The directive is grounded in a determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7–3.98 GHz frequency band, known as the 5G Lower C-Band, while operating in Canadian airspace. The FAA further determined that, during approach, landings, and go-arounds, interference from this band may cause certain airplane systems to not properly function, resulting in increased flightcrew workload while on approach with the flight director, autothrottle, or autopilot engaged. According to the directive, this malfunction risk could result in a reduced ability of the flightcrew to maintain safe flight and landing of the airplane.

The agency notes that the 5G Lower C-Band frequency range is close to the frequency bands used by radio altimeters, which operate in the 4.2–4.4 GHz range. The FAA also previously determined that radio altimeter anomalies undetected by automation or the pilot — particularly close to the ground, such as during landing flare — could lead to loss of continued safe flight and landing.

Regulatory History and Escalating Action

This directive is the latest in a series of rulemakings the FAA has pursued as 5G Lower C-Band deployment has expanded. The agency first issued AD 2021-23-12 (Amendment 39-21810, published December 9, 2021) for all transport and commuter category airplanes equipped with a radio altimeter, requiring AFM revisions to prohibit certain radio-altimeter-dependent operations when 5G Lower C-Band interference was identified through Notices to Air Missions (NOTAMs).

The FAA subsequently identified an additional hazard specific to Boeing 757 and 767 airplanes and issued AD 2022-04-05 (Amendment 39-21947, published February 14, 2022). That directive required AFM revisions incorporating specific operating procedures for landing distance calculations, instrument landing system (ILS) approaches, non-precision approaches, speedbrake deployment, and go-around and missed approaches — all tied to NOTAM-identified 5G interference zones.

The agency then determined that additional limitations were necessary as new 5G Lower C-Band base stations continued to deploy, with signals expected to cover most of the contiguous U.S., and as it found that radio altimeter anomalies could lead to increased flightcrew workload and flightcrew desensitization to warnings. This led to a further rulemaking, AD 2023-10-02 (Amendment 39-22438, published May 2023). The current directive — filed under Docket No. FAA-2026-7207 and Project Identifier AD-2026-00556-T — represents the next step in this progression, specifically addressing the Canadian airspace context.

Comment Process

Although issued as a final rule, the FAA is also requesting public comments. The agency states it will consider all comments received by the closing date and may amend the rule as a result. Comments are to reference Docket No. FAA-2026-7207 and Project Identifier AD-2026-00556-T and are to be submitted via methods listed in the notice's ADDRESSES section. Submissions containing Confidential Business Information (CBI) — defined as commercial or financial information customarily and actually treated as private — must be clearly designated as such and marked "PROPIN" on each page, and are to be directed separately to Ken Fairhurst, Continued Operational Safety Technical Advisor, FAA, 2200 South 216th St., Des Moines, WA 98198. Non-CBI comments will be posted publicly to regulations.gov without change.

What to Watch

• July 1, 2026: The effective date of the airworthiness directive. Operators of all Boeing 757 and 767 airplanes must have AFM revisions in place prohibiting radio-altimeter-dependent operations in Canadian airspace by this date.
• The FAA's comment window closes on a date specified in the notice; operators and affected parties should monitor regulations.gov under Docket No. FAA-2026-7207 for updates or potential amendments to the final rule.

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