Two proposed mandates are impacting your panel.
Here's where you stand.
FAA and Transport Canada directives already restrict certain operations for aircraft without tolerant radar altimeters. The proposed US rule would go further, reaching every radar altimeter in the contiguous US in two waves, airlines first. And Congress is still drafting the ADS-B IN mandate. FreeFlight is ready for both.
July 1, 2026
FAA and TCCA airworthiness directives now restrict radar-altimeter-dependent operations in Canadian airspace for aircraft without tolerant altimeters.
58,600
Radar altimeters the FAA estimates would need upgrade or replacement under its proposed US-wide rule.
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. One planned downtime event covers both.
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.
Is your aircraft affected?
Five questions. Sixty seconds. A clear verdict with your next steps, in writing.
The C-band clock is running.
In 2021 the first 5G airworthiness directives reached the airlines. On July 1, 2026 the second wave arrived: FAA directives now restrict radar-altimeter-dependent operations in Canadian airspace for transport and commuter category airplanes without tolerant altimeters, and Transport Canada’s own directives extend tolerance requirements to fixed-wing aircraft and rotorcraft. The published way out, on both sides of the border, is upgrading the altimeter.
The proposed US rule goes further, reaching every radar altimeter in the contiguous United States in two waves: the airlines first, expected 2029 to 2030, then everyone else, Part 91 and 135 included, roughly two years later. Full-power 5G service is slated to begin in the top 75 US markets by late 2030, before that second deadline arrives, and the airline wave consumes retrofit capacity first. The operators who move first choose their downtime.
TERRAIN SERIES | key features
- Stable AGL performance in RF-dense, low-visibility environments
- 1.3 lb sensor, 100 mA max at 28 VDC
- 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
- Certified to TSO-C87a, DO-160G, and DO-178C
The Next Mandate is Forming in Congress.
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 2026: FAA proposes interference-tolerance requirements for every radar altimeter in US airspace.
- Jul 1, 2026: New FAA and TCCA directives restrict operations in Canadian airspace for aircraft without tolerant altimeters.
- Jul 22, 2026: FCC votes on the Upper C-band auction order, including the altimeter retrofit rebate framework.
- Jul 2027: Statutory deadline for the FCC to complete the Upper C-band auction.
- Late 2030: Full-power 5G service begins in the top 75 US markets, following the first FAA-required altimeter retrofits.
- 2029 to 2032: Two-tier compliance window under the FAA's proposed rule: airlines first, all other operators roughly two years later.
Frequently Asked Questions
Is the US-wide radar altimeter rule final?
No. The FAA proposed it in January 2026 and the comment period closed March 9. The FAA has stated that compliance will require widespread equipment upgrades or replacement, and the final rule, expected after the FCC completes its Upper C-band order, will set the deadlines.
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 proposed rule covers every radar altimeter in the contiguous United States in two waves: Part 121 and 129 airlines first, expected 2029 to 2030, then all other operators, Part 91 included, roughly two years later. Two things arrive before that second deadline: the airline wave moves roughly 58,600 units through a finite retrofit pipeline first, and full-power 5G service begins in the top 75 US markets by late 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’s Upper C-band order creates a retrofit rebate program funded by auction winners. As drafted, it covers altimeters already installed in eligible aircraft, not spare inventory and not foreign-registered aircraft. The FCC votes on the order July 22, 2026, and rebate details go out for public comment by October 6, 2026. We will update this page as the program takes shape.
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.
