Telecoms agreed to voluntarily extend measures until risks cleared
By Ahmad Hathout
Transport Canada considered grounding aircraft after January 1, 2026 if telecoms did not agree to extend a years-long commitment to mitigate radiofrequency interference from 5G sites, according to a document obtained by Cartt.
Innovation, Science and Economic Development (ISED), the department managing the airwaves, first approved 5G exclusion zones around 26 major airports in 2021, which was then expanded to 35 airports in 2023. Expected to sunset on January 1, 2026, the measures were designed to protect existing radio altimeters – which measure a plane’s height above terrain by sending a rebounding radio wave toward the ground – until the aircraft were retrofitted with more modern designs.
But following concern about the lingering potential for interference even with retrofitted planes and a Transport Canada warning about the possible need to ground aircraft, the telecoms agreed on December 8 to voluntarily extend mitigation measures in the 3.5 GHz and 3.8 GHz mid-band spectrum, which, crucially, sit near the 4.2 to 4.4 GHz band used by the altimeters. Those mitigation measures put restrictions on site height, tower uptilt and the acceptable spurious emission level for base stations.
“5G mitigation measures requested by the aviation industry are largely based on an overly conservative methodology such as antennas pointing towards the sky at 90 degrees vertically, and the poor performance of some radio altimeters,” the ISED document reads.
The initial agreement extended the measures to June 30, 2026. But after an April meeting of the departments, telecoms and aviation industry, certain measures were extended to December 31, 2027, namely spurious emissions control and telecom coordination with Transport Canada and ISED at least 30 days before any new 3.8 GHz deployments above 70 metres near 246 Canadian airports. The parties agreed to check-ins until that new date.
“This extension allowed Transport Canada and Innovation, Science, and Economic Development Canada (ISED) to further collaborate closely with the aviation and telecommunications sectors and original equipment manufacturers,” a Transport Canada spokesperson told Cartt. “The reason for this was to allow adequate time for the determination of the next steps for safely lifting some mitigation measures and suggest ongoing recommended actions, based in scientific data and thorough analysis.”
The spokesperson added that the “overwhelming majority of aircraft registered in Canada, including the entire fleet of national aircraft operators are now considered retrofitted, or were already tolerant to 5G.” That said, “Canadian protection measures may be different than those in other countries, given that each country determines what is required based on their country’s spectrum environment,” the spokesperson added.
The mitigation measures’ sunset date of December 31, 2027, which aligns with a voluntary agreement between the FAA and telecoms in the U.S., is anticipated to be extended beyond January 1, 2028 “considering the availability of next-generation radio altimeters forecasted in the 2029-2033 timeframe,” the ISED document said.
ISED specifically noted that retrofitted radio altimeters from one manufacturer, which supplied devices to De Havilland and America’s Boeing, the maker of some of the most used commercial airplanes in the world, would still require mitigation measures beyond June 2026 — like planes that cannot be retrofitted.
“The same manufacturer has requested extremely low spurious emission levels from [5G] base stations (i.e. 16 times more stringent than ISED’s regulatory limit) in order to protect their radio altimeters,” the document said, adding the Canadian telecoms had confirmed that their 5G base stations meet this more stringent spurious emission level.
In July, the Federal Aviation Administration (FAA) in the United States issued a final rule requiring all radio altimeters to meet specific minimum performance requirements. The ruling came in the same week the Federal Communications Commission (FCC), the telecom regulator working with the FAA, made 160 megahertz of the radio altimeter’s immediately adjacent upper C-band (3.98 GHz to 4.2 GHz) available for wireless use at a later date.
“These new radio altimeters must withstand interference from wireless signals in neighboring spectrum bands and continue to provide accurate altitude readings to both pilots and integrated aircraft safety systems,” the FAA’s final rule states.
The FAA has set two deadlines by which planes operating in the United States must install, or upgrade to, new altimeters: for planes with 30 or more seats or a payload capacity of more than 7,500 pounds, the deadline is December 30, 2030, one day before the FCC authorizes the upper C-band for wireless use; the deadline for the other aircraft is October 31, 2034.
“If FAA takes no action to mandate minimum RA [radio altimeter] system performance, there would not only be uncertainty for aviation stakeholders, but in the wireless industry as well due to the increased likelihood that the wireless companies would not reap the full economic benefit of the spectrum,” the agency said in its final rule. “That is, the value of the spectrum license would decrease significantly because auction winners would have little confidence that they could initiate new wireless service on the dates designated by the FCC [rule]…”
An equivalent minimum performance requirement rule applicable to Canadian operators is “currently under review,” the Transport Canada spokesperson told us.
“While real‑world evidence has consistently shown no confirmed cases of harmful interference between 5G and radio altimeters, Canadian wireless operators voluntarily adopted temporary measures to help avoid any potential disruptions to travel schedules for Canadians and in the interest of supporting Canada’s aviation sector as it continues to update and retrofit aircraft with radio altimeters that meet modern technical standards,” Eric Smith, senior vice president of trade group Canadian Telecommunications Association, told Cartt in a statement.
“Similar voluntary steps were taken by U.S. wireless operators, not because the 5G technology posed a proven risk, but out of the same spirit of cooperation,” Smith added. “Our sector remains committed to working constructively with Transport Canada, ISED, and the aviation community towards the eventual phasing out of these temporary measures.”
In the meantime, Canadian telecoms received Transport Canada approval for an exemption to the voluntary agreement during the FIFA World Cup that allowed for specific 5G deployments using the 3.5 GHz band around Toronto Pearson International and Vancouver International airports.
“Transport Canada assessed the aviation safety risks associated with the proposed deviations and concluded that they would not introduce additional aviation safety risks,” the department spokesperson told us.
Photo via Air Canada
