The new FAA Radar Altimeter Rule and proposed ADS-B IN mandates are impacting your panel.
Here's where you stand.
Under the rule published July 31, 2026 and effective September 29, every radar altimeter on an aircraft operating in the 48 contiguous United States and the District of Columbia must meet the new tolerance standard, airlines by December 30, 2030 and all other operators by October 31, 2034.
FAA and Transport Canada directives already restrict certain operations for aircraft without tolerant radar altimeters.
And Congress is still drafting the ADS-B IN mandate.
FreeFlight is ready for both: shipping today, with upgrade paths already in work.
July 1, 2026
Canada now requires a 5G tolerant radar altimeter for unrestricted operations. Upgrading removes the limitations.
2030 / 2034
Compliance dates under the final rule. Part 121 and large Part 129 December 30, 2030. All other operators October 31, 2034.
396 to 10
House vote passing the ALERT Act, as Senate leaders press to add an ADS-B IN mandate.
Certified Today
TERRAIN SERIES and RANGR-IQ are TSO-certified and shipping now. Both have retrofit paths for future requirements.
READY ON BOTH FRONTS TO PROVIDE SAFETY IN ALL PHASES OF FLIGHT
Radar altimeters and ADS-B are FreeFlight’s core product lines, not line items in a larger suite. FreeFlight engineers are active on RTCA committees, SC-239 and SC-186, that shape the radar altimeter and ADS-B standards the coming rules will draw from. And every unit is designed for retrofit first: Terrain Series altimeters drop into legacy analog panels or glass cockpits without a panel redesign, and RANGR-IQ works with the displays you already fly, including Pro Line 21™ and InSight Flight Deck. The result is a compliance upgrade sized to the requirement, not a full panel project priced around it.
FreeFlight recommended provisions that keep the upgrade practical, and the FAA adopted them: one upgrade satisfies both the new rule and the directives already in force.
Is your aircraft affected?
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The C-band clock is running.
FOR CANADIAN OPERATORS
Canada lifted its airport exclusion zones and uptilt limits on July 1, 2026. What protection remains applies only to altimeters that are already tolerant. Transport Canada sets tolerance in CF-2024-14 for airplanes and CF-2024-15 for rotorcraft and recognizes FAA tolerance standards. All Terrain Series models qualify today.
Flying into the contiguous US adds the FAA rule on the same 2030 and 2034 dates, without the FCC rebate. Transport Canada is urging operators to book slots and parts now.
FOR US OPERATORS
More than a dozen airworthiness directives are in force today for the Lower C-band. A tolerant altimeter clears those now, and the rule sets the higher bar.
Published July 31, 2026 and effective September 29, the FAA rule requires every radar altimeter on an aircraft operating in the 48 contiguous United States and the District of Columbia to meet the new tolerance standard. Airlines comply by December 30, 2030 and all other operators by October 31, 2034. Upper C-band service is authorized to begin December 31, 2030, so operators working to 2034 have a practical planning point four years earlier. Equipping on your own schedule means the upgrade fits a maintenance visit you already have booked.
TERRAIN SERIES | key features
- Stable AGL performance in RF-dense, low-visibility environments
- 1.30 lb or less, 300 mA max at 28 VDC, digital output
- 5G-resilient DSP with C-band filtering
- Dual-install capability (RA-6500) for redundancy
- High refresh rates for low-altitude precision
- RA-6500, RA-5500, and RA-4500 MK II to fit the airframe and the mission
- TSO-C87a approved, qualified to DO-160G, software to DO-178C
- Meets the FAA and Transport Canada directives in force today, with a service bulletin path to the new rule in development
The Next ADS-B Mandate is Forming
The ALERT Act passed the House 396 to 10 in April. Senate Commerce leadership has objected that it lacks an ADS-B IN requirement and is pressing to add one, with the ROTOR Act still in play. Operators who equipped for ADS-B Out remember the 2019 retrofit queue. The calm before a rule is the cheapest time to equip, and IN pays for itself in situational awareness whether or not a mandate lands.
RANGR-IQ | KEY FEATURES
- TIS-B traffic and TCAS II integration. Hybrid surveillance from taxi to touchdown.
- Fuses ADS-B IN and TCAS II data to cut duplicate targets and cockpit workload
- Proven integrations including Pro Line 21 and InSight, plus FIS-B weather, NOTAMs, and TFRs
- Ethernet, ARINC 429, and serial interfaces
- Wi-Fi connectivity for EFB and tablet applications
- TSO-certified, DAL B-rated, low SWaP, retrofit, shipping now
Bill tRACKER | Last updated July 2026.
- ALERT Act (H.R. 7613): Passed the House 396 to 10 in April 2026. In Senate Commerce, where leadership is pressing to add an ADS-B IN requirement.
- ROTOR Act (S. 2503 / H.R. 6222): Passed the Senate unanimously in December 2025. Failed a House suspension vote in February 2026. Watching for revival or merger with ALERT.
- Helicopter Safety Parity Act (H.R. 8226): Introduced April 2026, in committee.
- FAA rulemaking watch: Press reports indicate the FAA has directed staff to draft an ADS-B IN requirement independent of Congress. The FAA has not confirmed and no docket exists. We will update this entry when one appears.
Built for exactly this moment.
Active in the standards process, continually evaluating against what’s coming, and built to move the day a directive takes effect.
- Standards before they're standard. The RTCA work now in draft will define the next radar altimeter TSO. FreeFlight is engineering against it before it publishes, not after.
- Recognized on both sides of the border. Altimeters meeting FAA tolerance standards are recognized as tolerant under Transport Canada's directives. One upgrade satisfies two regulators.
- Retrofit first, by design. Whether the panel is glass or legacy analog, the TERRAIN Series fits: RA-6500, RA-5500, and RA-4500 MK II, with RAD-40 and RAD-45 indicator options across the line. No panel redesign.
- One downtime event. TERRAIN Series and RANGR-IQ can be sequenced as a single scheduled installation through the authorized dealer network.
Timeline
- Dec 2021: First FAA airworthiness directives address 5G interference with radar altimeters.
- Jul 2025: Congress directs the FCC to auction the Upper C-band, adjacent to altimeter spectrum.
- Jan 7, 2026: FAA proposes interference-tolerance requirements in the 48 contiguous states and the District of Columbia.
- Jul 1, 2026: Canada lifts its airport exclusion zones and uptilt limits. FAA directives add flight manual limitations for transport and commuter category airplanes flying to Canada without tolerant altimeters.
- Jul 24, 2026: FAA signs the final rule on interference-tolerant radio altimeters, issued with the FCC's Upper C-band Report and Order and its altimeter retrofit rebate framework.
- Jul 31, 2026: Rule published in the Federal Register, 91 FR 48656. Effective September 29, 2026.
- Jul 2027: Statutory deadline for the FCC to complete the Upper C-band auction, which funds the altimeter retrofit rebate.
- Dec 30, 2030: Compliance date for Part 121 and large Part 129 operators.
- Dec 31, 2030: Upper C-band service may begin in the top 75 markets, roughly 70 percent of the US population. Voluntary wireless commitments end.
- Jul 1, 2031: Deadline for Upper C-band service to reach all remaining markets.
- Oct 31, 2034: Compliance date for all remaining operators.
Frequently Asked Questions
What exactly changed on July 1?
FAA airworthiness directives took effect placing flight manual limitations on radar-altimeter-dependent operations in Canadian airspace for transport and commuter category airplanes without tolerant altimeters. Transport Canada’s own directives, CF-2024-14 for fixed-wing aircraft and CF-2024-15 for rotorcraft, set the tolerance requirements in Canada, and altimeters meeting FAA tolerance standards are recognized as tolerant under them. Current Canadian mitigations run through at least December 31, 2027. Upgrading the altimeter terminates the limitations.
My aircraft never leaves the US. Why should I care now?
The final rule covers every radar altimeter on an aircraft operating in the 48 contiguous United States and the District of Columbia, in two waves. Part 121 and large Part 129 by December 30, 2030, then all other operators, Part 91 included, by October 31, 2034. The FAA set that four-year gap in response to comments. Two things arrive before the second deadline: the first wave moves a share of 58,514 units across 40,730 civil aircraft through a finite retrofit pipeline, and Upper C-band service begins December 31, 2030. Equipping early means choosing your own downtime.
Which TERRAIN SERIES unit fits my aircraft?
All three Terrain Series altimeters, the RA-6500, RA-5500, and RA-4500 MK II, pair with RAD-40 and RAD-45 indicators for legacy analog panels or integrate with glass displays. The right unit comes down to airframe and mission; an authorized installer can confirm fit for your aircraft.
Will there be help paying for the upgrade?
The FCC adopted the order July 24, 2026. Funding is expected within six to twelve months of the Upper C-band auction, which must be complete by July 4, 2027. Eligibility terms follow the auction. We will update this page as the program takes shape.
What happens if my aircraft is not compliant by December 30, 2030?
Two things change at the end of 2030 regardless of your compliance date. Upper C-band service begins December 31, 2030, and the voluntary wireless commitments holding Lower C-band emissions down lapse the same day.
The FAA has stated it plans to issue superseding airworthiness directives for transport and commuter category airplanes not shown to meet the new tolerance mask, prohibiting low-visibility approach and landing operations after December 30, 2030 until the aircraft is compliant. That includes CAT II and CAT III, and SA CAT I and SA CAT II. The applicability is by aircraft category, not by operating rule, so a transport or commuter category airplane on the 2034 date can still pick up limitations in 2030.
Is ADS-B IN mandated?
Not yet. The ALERT Act passed the House 396 to 10 and Senate Commerce leadership is pressing to add an ADS-B IN requirement. FreeFlight tracks both bills on this page monthly.
Is the FAA writing its own ADS-B In rule?
Reporting indicates the FAA has directed staff to draft an ADS-B In requirement of its own, moving in parallel as the ALERT and ROTOR Acts stall in Congress. As described, the draft would reach nearly all aircraft in civilian airspace, expanding beyond today’s ADS-B Out requirement, and follows the January 2025 midair collision near Reagan National. The FAA has declined to comment on the draft, and the agency has acknowledged it cannot impose a costly new mandate without congressional authority. No rulemaking docket exists yet. We track both the bills and any FAA action on this page monthly.
