FAA 5G Upper C-Band Mandates Impact Aviation Radio Altimeters

This article is based on an official statement from the National Business Aviation Association (NBAA) and regulatory filings regarding the FAA‘s January 2026 Notice of Proposed Rulemaking.

NBAA Mobilizes Coalition to Address New FAA 5G “Upper C-Band” Mandates

The National Business Aviation Association (NBAA) announced on January 16, 2026, that it has joined a broad coalition of industry stakeholders to address significant technical and logistical challenges posed by the Federal Aviation Administration’s (FAA) latest regulatory proposal. The FAA’s Notice of Proposed Rulemaking (NPRM), published on January 7, 2026, outlines strict new performance standards for radio altimeters to mitigate interference from future 5G telecommunications networks operating in the “Upper C-Band” spectrum.

This new regulatory push is driven by the “One Big Beautiful Bill Act” of 2025, federal legislation that mandates the auction of the 3.98–4.2 GHz spectrum band for commercial wireless use by July 2027. According to the NBAA, the aviation industry is now facing a tight timeline to develop, certify, and install next-generation equipment before these new wireless services go live, with initial compliance deadlines projected between 2029 and 2032.

The NBAA is collaborating with Airlines for America (A4A), original equipment manufacturers (OEMs), and the Radio Technical Commission for Aeronautics (RTCA) to ensure that the proposed rules are technically feasible within the mandated timeframe.

The Shift to Upper C-Band: A New Technical Challenge

While the aviation industry spent much of 2022 and 2023 retrofitting aircraft with filters to protect against 5G signals in the “Lower C-Band” (3.7–3.98 GHz), the new mandate addresses a distinct and more complex challenge. The upcoming expansion involves the 3.98–4.2 GHz band, which sits significantly closer to the 4.2–4.4 GHz frequency range used by radio altimeters, critical safety instruments that measure an aircraft’s height above terrain.

According to technical details released in the NPRM, the proximity of these high-power wireless signals renders previous “filter-only” solutions insufficient. The NBAA notes that the new mandate will likely require the full replacement of radio altimeter units with new hardware designed to meet stricter Minimum Operational Performance Standards (MOPS).

The “Solutions Gap”

A primary concern raised by the NBAA is the current lack of commercially available equipment to meet the FAA’s proposed standards. The industry is currently in a “solutions gap,” where the regulation demands performance specifications that manufacturers are still in the process of defining.

Heidi Williams, NBAA Senior Director of Air Traffic Services and Infrastructure, highlighted this discrepancy in the association’s statement:

“The timelines proposed will be challenging in light of solutions that haven’t yet come to market… Achieving the proposed rule’s objectives, on any timeline, will require continued collaboration between industry stakeholders, the FAA and standards organizations.”

Timelines and Compliance Deadlines

The FAA’s proposal sets a rigid schedule driven by the legislative requirement to auction the spectrum by July 2027. Based on the NPRM and industry analysis, the key milestones are as follows:

• March 9, 2026: Deadline for industry comments on the FAA’s NPRM.
• March 2027: Target date for RTCA Special Committee 239 to publish the new MOPS technical standards.
• July 2027: FCC deadline to auction the Upper C-Band spectrum.
• 2029–2032: Estimated window for new 5G services to go live; this serves as the initial compliance deadline for Part 121 (airlines) and Part 129 (foreign carriers).
• 2031–2034: Compliance deadline for general and business aviation, which are granted an additional two years after the initial deadline.

The FAA estimates that this rule will affect approximately 58,600 aircraft in the U.S. fleet. Industry estimates cited in the reporting suggest the total cost for these fleet-wide upgrades could exceed $4.5 billion.

AirPro News Analysis: Legislating Physics

The friction between the “One Big Beautiful Bill Act” and aviation safety highlights a recurring tension in modern infrastructure development: the pace of legislation versus the pace of engineering. Unlike the previous 5G rollout, where filters could be applied to existing hardware, the Upper C-Band expansion requires the invention and certification of entirely new avionics.

With the RTCA not expected to finalize the technical standards until March 2027, just months before the spectrum is legally required to be auctioned, manufacturers will be under immense pressure. If the standards are delayed, or if the certification process hits snags, the 2029 compliance window could close rapidly, potentially risking a repeat of the flight disruptions seen during the initial 5G rollout. The “collaboration” the NBAA speaks of is effectively a race to ensure the regulatory requirements do not outpace physical manufacturing capabilities.

Industry Collaboration Efforts

To mitigate these risks, the NBAA is working closely with the RTCA Special Committee 239 (SC-239). In late 2025, this committee shifted its focus from producing a guidance document to developing a full Minimum Operational Performance Standard (MOPS). This shift is intended to ensure a robust, long-term technical solution that creates altimeters immune to the closer, more powerful 5G signals.

Airlines for America (A4A) echoed the need for cooperation in a statement regarding the new spectrum usage:

“We have been working collaboratively with the telecommunications industry, the FAA and the FCC to identify solutions that ensure our nation’s airspace remains safe while allowing the spectrum to be used.”

Frequently Asked Questions

Which aircraft are affected by the new rule?

The FAA estimates the rule covers approximately 58,600 aircraft, including commercial airliners (Part 121), foreign carriers (Part 129), and business/general aviation aircraft equipped with radio altimeters.

When must business jets comply?

General and business aviation operators have a compliance deadline set for two years after the initial commercial deadline. Based on current projections for 5G deployment, this places the business aviation deadline between 2031 and 2034.

Why can’t operators just use the filters installed in 2023?

The filters installed previously were designed for the “Lower C-Band” (3.7–3.98 GHz). The new legislation opens the “Upper C-Band” (3.98–4.2 GHz), which is much closer to the altimeter’s operating frequency. The existing filters cannot block interference from this adjacent band without degrading the altimeter’s performance, necessitating full unit replacement.

Sources:
NBAA Statement on 5G Interference
Federal Aviation Administration (NPRM Filings)