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ADS-B mandate for Class B airspace in Canada comes into effect

May 17, 2024  By Phil Lightstone

Since 2020, NAV Canada has been apprising aircraft owners and operators of their plans for Automatic Dependent Surveillance-Broadcast (ADS-B) deployments in Canada. In fact, Canadian ADS-B has been in the planning and deployment stages long before then, starting with the creation of Aireon in 2011.

Now, effective May 16, 2024, aircraft entering Class B airspace (12,500 feet and above) will be required to be equipped with ADS-B OUT transponders operating on 1090 MHz. NC recognizes that equipage may be an issue. In fact, Cirrus Aircraft, Diamond Aircraft and Kodiak (a Daher company), have not completed their engineering studies. Purchasing a brand new Cirrus SR20 or SR22 aircraft will be equipped with a Garmin transponder which does not support antenna diversity. This is a short-term problem, while airframe manufacturers finalize the engineering efforts. Of note, Cirrus’s Vision Jet is equipped with a mode S transponder with antenna diversity.

To bridge the gap, NAV Canada (NC) has published AIC 26/23, which provides aircraft operators and pilots a process to request an exemption (on a flight-by-flight basis), allowing the flight to enter Class B airspace without ADS-B equipage. The request is submitted through NC’s website, no earlier than three business days before the flight (or five days if the flight takes place on a Sunday).

Each request is reviewed by a NC staffer and either approved or rejected. At the time of this article, discussions with NC staff, indicated that they had yet to be briefed on the approval process. Aircraft owners and operators can request a blanked exemption. This was created for those owner operators who are unable to equip based upon no engineering solution or equipage delays caused by product shortages or shop timelines. The ADS-B accommodation request form can be found at


For Canadian aircraft operating in American class A, B, C and ADIZ airspace, ADS-B OUT will be mandatory. The US ADS-B environment is based upon a fabric of ground stations. The typical US general aviation aircraft is equipped with antennas on the underside of the fuselage. Compliance to the Aireon’s space based fabric will require an antenna installed on the top of the aircraft (similar to the antenna for TCAS).

To facilitate compliance to both US and Canadian requirements, an ADS-B transmitter which supports antenna diversity will be required. Michael Kussatz of Garmin International of Olathe, Kansas states “this is the equivalent of having two transponders in a single product”. The requirement of antenna diversity adds complexity and cost to the technology as well as to the installation time.

For those pilots on a flight, not equipped with NC compliant ADS-B transponders, who may wish to enter Class B airspace, due to weather avoidance, will most likely be sanctioned by NC through the issuance of a CADORs. While it is not expected that ATC will deny the aircraft access to the airspace for safety reasons, the CADORS may be issued. The CADORS process incudes escalation to TC. It’s unclear (at this time) if monetary penalties and other sanctions would be applied against the pilot(s) and operator.

NC’s original plan saw two phases: Phase 1 – February, 2021: Class A and Class E (above FL600) airspace; Phase 2 January 27, 2022 Class B airspace. But these plans were changed, pushing Class A and B to 2023, and changed again with Class B pushed to May 16, 2024. At that time, NC’s plans for Class C, D and E airspace was starting no earlier than 2026. That has been changed to no later than 2028. Recently, TC issued Advisory Circular AC 500-029, effective April 22, 2022 which outlines the compliance requirements.

To enter Class B airspace, starting in May 16, 2024, aircraft will be required to have ADS-B OUT with antenna diversity. Transport Canada (TC) has updated the Canadian Aviation Regulations (CARs), Airworthiness Chapter 551 – Aircraft Equipment and Installation, 551.103 Transponder and Automatic Pressure Altitude Reporting Equipment (effective 2023/07/17) to state that ADS-B OUT must include antenna diversity on specific types of transponders. (

The question regarding the need for antenna diversity is a bit confusing for General Aviation aircraft owners. The CARs section 551.103 indicate: “(4) Antenna installation (effective 2023/07/17) the antennas of the ADS-B equipment shall be installed so that: For Class A1, A2, A3 or B1 installed equipment, they comply with all antenna installation requirements specified in section 3.3 of RTCA DO-260B for a diverse installation and they transmit alternately towards the bottom and the top of the aircraft per the requirements specified in section of RTCA DO-260B (“transmitting diversity”); or for Class A1S or B1S installed equipment, they comply with antenna installation requirements specified in section 3.3 of RTCA DO-260B for single antennas and it can be demonstrated that the equipment transmits satisfactorily to ground-based as well as space-based receiver in the normal aircraft operating envelope.”

TC has changed the CARs, allowing for non-antenna diverse transponders to be used based upon passing a test. Brant Aero, an airframe and avionics shop located in Brantford ON, are a bit confused on the specifications. From their perspective, testing an ADS-B OUT installation on the ground using their test tools, will comply with TC’s requirements.

However, NC has their own testing tool, which for many ADS-B OUT installations are failing (a single parameter) while airborne. Industry insiders are finding that many 1090 MHz ADS-B installations with antenna diversity are failing NC’s airborne test (PAPR), specifically the PYIA criteria. It’s unclear (at this time), how NC is dealing with this dichotomy. This confusion is causing some aircraft owners to delay equipage (and costs), until these issues are resolved by TC and NC. The implication being that aircraft owners and operators can right size the installation (or do nothing if equipped with 1090 MHz transponders equipped with single antennas).

While NC’s and TC’s planning and announcements for Canadian ADS-B have been on-going since before 2011, we are getting closer to the activation of the mandate to more Canadian airspace. Stay tuned over the next few months as NC and TC react to the number of issues and concerns from Canadian and US stakeholders.


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