Attention:
All Canadian Operators equipped with a radio altimeter and air traffic service
| File Classification No.: | Z 5000-35 |
|---|---|
| RDIMS No.: | 21276193 |
| Document No.: | CASA 2025-14 |
| Issue No.: | 01 |
| Effective Date: | 2025-12-24 |
Purpose:
The purpose of this Civil Aviation Safety Alert (CASA) is to provide an update on the 5G spectrum environment in Canada. Major telecommunications service providers in Canada have voluntarily agreed to postpone the sunset of existing 5G mitigation measures until June 30, 2026. This provides additional time for Transport Canada (TC) and Innovation, Science, and Economic Development (ISED) Canada to work with the aviation and telecommunication industries, including the Original Equipment Manufacturers, on next steps prior to lifting the mitigation measures in a safe manner based on scientific data and analysis.
In 2024, TC issued Airworthiness Directive (AD) CF-2024-14 (for fixed-wing aircraft) and CF-2024-15 (for rotorcraft) that describe current Radio Altimeter (RadAlt) tolerance requirements in Canada.
These ADs remain effective while current 5G mitigations are voluntarily maintained by Canadian telecommunications operators.
Background:
ISED is the spectrum regulator in Canada. Since December 2021, ISED has allowed flexible use networks and technology (including 5G) in the frequency bands 3450 to 3650 MHz (3500 MHz). ISED allowed (5G) in the frequency band 3650-3900 MHz (3800 MHz) following its auction on October 24, 2023. Deployment in the 3800 MHz band started on May 29, 2024. Additionally, ISED has allowed non-competitive local licensing (NCLL) framework to operate in the frequency band 3900-3980 MHz. The frequency bandwidth allocated to these services is close to one used by aircraft radio altimeters (4200-4400 MHz).
The United States has deployed 5G as well as countries in Europe and Asia, with power levels and spectrum mitigations varying from country to country.
Given the worldwide expansion of this technology, data gathered by the Federal Aviation Administration (FAA), ISED, the Radio Technical Commission for Aeronautics (RTCA), and others, TC concluded there exists a possibility of disturbance for certain RadAlt models by 5G radio waves in numerous operational scenarios in the frequency band 3450-3980 MHz at or above a specific power spectral density (PSD) curve threshold, which may affect aviation safety.
In July 2023, ISED established technical rules in the 3450-3900 MHz bands to mitigate potential interference to radio altimeters, which extends the technical rules for the 3450-3650 MHz band (3500 MHz) that were initially published by ISED in November 2021. The current protection measures which will be voluntarily maintained until June 30, 2026, include:
- Exclusion and protection zones to mitigate interference to aircraft having a certain level of 5G tolerance at certain runways (see Appendix B) at 35 airports covering 93% of air traffic in Canada;
- Reduced fundamental emissions power levels at the runways at the 35 airports having protection and exclusion zones, implemented by E.I.R.P. elevation maskFootnote 10; and
- Reduced fundamental emissions power levels based on degree of antenna uptilt above the horizon, nationwide, to minimize skyward emissions from 5G base stations.
Protected runways (in Appendix B) only offer protection to aircraft that can withstand a certain level of 5G fundamental and spurious emissions.
Upcoming 5G environment:
Although Telecommunications operators have agreed to voluntarily extend existing 5G mitigation measures until June 30, 2026, an aircraft may be subject to stricter aviation limitations and/or retrofit expectations due to the sunset of current 5G mitigations. On January 1st, 2028, remaining spectrum mitigations will also sunset, which may further alter aviation limitations and/or retrofit expectations.
Further details on the 5G mitigations being sunset are included in Appendix D.
Ongoing recommended action:
- TC urges all operators to retrofit their aircraft to meet RadAlt tolerance requirements described in ADs CF-2024-14 (for fixed-wing aircraft) and CF-2024-15 (for rotorcraft) by securing maintenance slots, parts, and supplemental type certificates (STCs) if necessary.
- In the event of an actual disturbance of radio altimeter, it is imperative that flight crew report the event to the Air Traffic Service as soon as possible, regardless of the location of the occurrence be it domestic or foreign airspace. Pilot in command and operator are to complete the ‘Radio Altimeter Disturbance/Interference Report’ in Appendix C: Radio Altimeter Disturbance/Interference Report. RadAlt Disturbance/interference Reports would assist TC in assessing 5G interference and are strictly non-punitive. Operators reporting RadAlt disturbance/interference will not be penalized where irregular flight operations are caused by a malfunctioning RadAlt. TC is thankful for the voluntary cooperation of all operators in this process.
Contact office:
For more information concerning this issue, contact the AART Documentation Services AARTDocServices-ServicesdocAART@tc.gc.ca.
Original signed by
Jamie-Lee MacDermid
Executive Director, Standards
Civil Aviation
The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.
Appendix A: Criteria for Radio Altimeter Tolerance in Canada
In Canada, Radio Altimeter tolerance requirements are established in TCCA ADs CF-2024-14 (for fixed-wing aircraft) and CF-2024-15 (for rotorcraft).
These ADs also confirmed that aircraft meeting FAA AD 2023-10-02 RadAlt tolerance requirements (for fixed-wing aircraft) and FAA AD 2023-11-07 (for rotorcraft) are considered RadAlt tolerant in Canada.
FAA ADs may tailor future 5G-related Canadian ADs.
Appendix B: List of protected runways
Table 1 identifies the runways which are voluntarily protected for the 3500 MHz band and 3800 MHz band until June 30, 2026.
Note: Airports indicated in Bold typeface are subject to medium-power deployment in the 3900 MHz band.
Table 1: 5G Protected Runways, until June 30, 2026
| Airport Name | Protected Runways | |
|---|---|---|
|
1 |
Abbotsford International Airport/Aéroport International d'Abbotsford | RWY-07/25 |
|
2 |
Calgary International Airport/Aéroport International de Calgary | RWY-08/26 |
| Calgary International Airport/Aéroport International de Calgary | RWY-11/29 | |
| Calgary International Airport/Aéroport International de Calgary | RWY-17L/35R | |
| Calgary International Airport/Aéroport International de Calgary | RWY-17R/35L | |
|
3 |
Charlottetown International Airport/Aéroport International de Charlottetown | RWY-03/21 |
| Charlottetown International Airport/Aéroport International de Charlottetown | RWY-10/28 | |
|
4 |
Churchill Airport/Aéroport de Churchill | RWY-15/33 |
|
5 |
Comox Valley Airport/Aéroport de Comox Valley | RWY-12/30 |
| Comox Valley Airport/Aéroport de Comox Valley | RWY-18/36 | |
|
6 |
Deer Lake Regional Airport/Aéroport Régional de Deer Lake | RWY-07/25 |
|
7 |
Edmonton International Airport/Aéroport International d'Edmonton | RWY-02/20 |
| Edmonton International Airport/Aéroport International d'Edmonton | RWY-12/30 | |
|
8 |
Erik Nielsen Whitehorse International Airport/Aéroport International Erik Nielsen de Whitehorse | RWY-14R/32L |
|
9 |
Fort McMurray International Airport/Aéroport International de Fort McMurray | RWY-08/26 |
|
10 |
Fredericton International Airport/Aéroport International de Fredericton | RWY-09/27 |
| Fredericton International Airport/Aéroport International de Fredericton | RWY-15/33 | |
|
11 |
Gander International Airport/Aéroport International de Gander | RWY-03/21 |
| Gander International Airport/Aéroport International de Gander | RWY-13/31 | |
|
12 |
Goose Bay Airport/Aéroport de Goose Bay | RWY-08/26 |
| Goose Bay Airport/Aéroport de Goose Bay | RWY-15/33 | |
|
13 |
Greater Moncton Roméo LeBlanc International Airport /Aéroport International Roméo LeBlanc du Grand Moncton | RWY-06/24 |
| Greater Moncton Roméo LeBlanc International Airport /Aéroport International Roméo LeBlanc du Grand Moncton | RWY-11/29 | |
|
14 |
Halifax Stanfield International Airport/Aéroport International de Halifax | RWY-05/23 |
| Halifax Stanfield International Airport/Aéroport International de Halifax | RWY-14/32 | |
|
15 |
Iqaluit Airport/Aéroport d'Iqaluit | RWY-16/34 |
|
16 |
J.A. Douglas McCurdy Sydney Airport/Aéroport de Sydney J.A. Douglas McCurdy | RWY-06/24 |
| J.A. Douglas McCurdy Sydney Airport/Aéroport de Sydney J.A. Douglas McCurdy | RWY-18/36 | |
|
17 |
John C. Munro Hamilton International Airport /Aéroport International John C. Munro d'Hamilton | RWY-06/24 |
| John C. Munro Hamilton International Airport /Aéroport International John C. Munro d'Hamilton | RWY-12/30 | |
|
18 |
Kelowna International Airport/Aéroport International de Kelowna | RWY-16/34 |
|
19 |
London International Airport/Aéroport International de London | RWY-09/27 |
| London International Airport/Aéroport International de London | RWY-15/33 | |
|
20 |
Mirabel International Airport/Aéroport Internationale de Mirabel | RWY-06/24 |
| Mirabel International Airport/Aéroport Internationale de Mirabel | RWY-11/29 | |
|
21 |
Montréal-Pierre Elliott Trudeau International Airport/Aéroport International Pierre Elliott Trudeau de Montréal | RWY-06L/24R |
| Montréal-Pierre Elliott Trudeau International Airport/Aéroport International Pierre Elliott Trudeau de Montréal | RWY-06R/24L | |
| Montréal-Pierre Elliott Trudeau International Airport/Aéroport International Pierre Elliott Trudeau de Montréal | RWY-10/28 | |
|
22 |
North Bay Jack Garland Airport/Aéroport North Bay Jack Garland | RWY-08/26 |
|
23 |
Ottawa International Airport/Aéroport International d'Ottawa | RWY-07/25 |
| Ottawa International Airport/Aéroport International d'Ottawa | RWY-14/32 | |
|
24 |
Prince George Airport/Aéroport International de Prince George | RWY-06/24 |
| Prince George Airport/Aéroport International de Prince George | RWY-15/33 | |
|
25 |
Québec City Jean Lesage International Airport/Aéroport International Jean-Lesage de Québec | RWY-06/24 |
| Québec City Jean Lesage International Airport/Aéroport International Jean-Lesage de Québec | RWY-11/29 | |
|
26 |
Regina International Airport/Aéroport International de Regina | RWY-08/26 |
| Regina International Airport/Aéroport International de Regina | RWY-13/31 | |
|
27 |
Saskatoon John G. Diefenbaker International Airport/Aéroport International John G. Diefenbaker de Saskatoon | RWY-09/27 |
| Saskatoon John G. Diefenbaker International Airport/Aéroport International John G. Diefenbaker de Saskatoon | RWY-15/33 | |
|
28 |
St. John’s International Airport/Aéroport International de St. John's | RWY-02/20 |
| St. John’s International Airport/Aéroport International de St. John's | RWY-11/29 | |
| St. John’s International Airport/Aéroport International de St. John's | RWY-16/34 | |
|
29 |
Stephenville Dymond International Airport/Aéroport International Stephenville Dymond | RWY-09/27 |
|
30 |
Thunder Bay International Airport/Aéroport International de Thunder Bay | RWY-07/25 |
| Thunder Bay International Airport/Aéroport International de Thunder Bay | RWY-12/30 | |
|
31 |
Toronto Pearson International Airport/Aéroport International Pearson Toronto | RWY-05/23 |
| Toronto Pearson International Airport/Aéroport International Pearson Toronto | RWY-06L/24R | |
| Toronto Pearson International Airport/Aéroport International Pearson Toronto | RWY-06R/24L | |
| Toronto Pearson International Airport/Aéroport International Pearson Toronto | RWY-15L/33R | |
| Toronto Pearson International Airport/Aéroport International Pearson Toronto | RWY-15R/33L | |
|
32 |
Vancouver International Airport/Aéroport International de Vancouver | RWY-08L/26R |
| Vancouver International Airport/Aéroport International de Vancouver | RWY-08R/26L | |
| Vancouver International Airport/Aéroport International de Vancouver | RWY-13/31 | |
|
33 |
Victoria International Airport/Aéroport International de Victoria | RWY-03/21 |
| Victoria International Airport/Aéroport International de Victoria | RWY-09/27 | |
| Victoria International Airport/Aéroport International de Victoria | RWY-14/32 | |
|
34 |
Winnipeg James Armstrong Richardson International Airport/Aéroport International James Armstrong Richardson de Winnipeg | RWY-13/31 |
| Winnipeg James Armstrong Richardson International Airport/Aéroport International James Armstrong Richardson de Winnipeg | RWY-18/36 | |
|
35 |
Yellowknife Airport/Aéroport de Yellowknife | RWY-10/28 |
| Yellowknife Airport/Aéroport de Yellowknife | RWY-16/34 |
Appendix C: Radio Altimeter Disturbance/Interference Report
Available online:
https://wwwapps.tc.gc.ca/Corp-Serv-Gen/5/forms-formulaires/searchrs.aspx?formnumber=26-0870
Appendix D: List of effective 5G mitigations in Canada
In Canada, today:
| Frequency BandFootnote 1 | Where | Airport EIRP elevation maskFootnote 2 | National Tilt restrictionFootnote 3 | Height/Power Combination limitsFootnote 4 | Exclusion zoneFootnote 5 | Max possible PowerFootnote 6 | Max possible Spurious (TRP or conducted)Footnote 7 |
|---|---|---|---|---|---|---|---|
| 5G 3500 MHz (3450 to 3650) | At protected airports | Yes | N/A, other is more restrictive | Yes - Loosely "Based" on FAA Group 3A curve.Footnote 8 | Yes | 61 dBm/MHz EIRP | -30 dBm/MHz |
| At Non-protected Airports | No | Yes | No, only tower obstruction limits afforded by OCS.Footnote 9 | No | 61 dBm/MHz EIRP | -30 dBm/MHz | |
| 5G 3800 MHz (3650 to 3900) | At protected airports | Yes | N/A, other is more restrictive | Yes - "Based" on FAA Group 3B curve. | Yes | 61 dBm/MHz EIRP | -30 dBm/MHz |
| At Non-protected Airports | No | Yes | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz |
In Canada, on 1 July 2026: (changes from today marked in bold)
| 5G 3500 MHz (3450 to 3650) | At protected airports – None remaining | No | No | No, only tower obstruction limits afforded by OCS | No | 61 dBm/MHz EIRP | -30 dBm/MHz |
|---|---|---|---|---|---|---|---|
| Frequency Band | Where | Airport EIRP elevation mask | National Tilt restriction | Height/Power Combination limits | Exclusion zone | Max possible Power | Max possible Spurious |
| At Non-protected Airports | No | No | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz | |
| 5G 3800 MHz (3650 to 3900) | At protected airports | Yes | N/A, other is more restrictive | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz |
| At Non-protected Airports | No | No | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz |
In Canada, on 1 January 2028: (changes from 2026 marked in bold)
| Frequency Band | Where | Airport EIRP elevation mask | National Tilt restriction | Height/Power Combination limits | Exclusion zone | Max possible Power | Max possible Spurious |
|---|---|---|---|---|---|---|---|
| 5G 3500 MHz (3450 to 3650) | At protected airports – none remaining | No | No | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz |
| At Non-protected Airports | No | No | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz | |
| 5G 3800 MHz (3650 to 3900) | At protected airports – none remaining | No | No | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz |
| At Non-protected Airports | No | No | No, only tower obstruction limits afforded by OCS. | No | 61 dBm/MHz EIRP | -30 dBm/MHz |