Toronto and Montreal Halt Departures as FAA Ground Stop Spills Into Canada

More than 2,700 flights into, out of, or within the US had been canceled by 6:20 p.m. Eastern on Friday, and Canada's two largest airports are now holding departures too. Toronto Pearson International and Montréal-Trudeau International both issued ground stops (an order halting departing flights) as the Federal Aviation Administration's nationwide US ground stop cascaded across the border.

NAV CANADA, the privately run nonprofit that owns and operates Canada's civil air traffic system, said its own systems are "operating normally" and that it ordered the stops to "safely manage traffic volumes." In a post on X, it told travellers to "expect delays and check with your airline."

Toronto and Montreal both listed the reason for their stops as "other" in the FAA's airspace advisory. Toronto flagged that the "probability of extension is high (greater than 60%)." Translation: the airport expects the disruption to last, and sellers of transborder air should plan accordingly.

Why would Canadian airports stop their own planes?

The mechanism is diversion, not contagion. Mark Stephens, a retired Delta Air Lines pilot, told Business Insider that the airports are likely preparing for US-bound international flights that need somewhere to land. Planes already on the ground will return to their gates, he said, which makes traffic management essential to absorb the extra volume.

The numbers back that up. Cirium, an aviation analytics company, counted at least 600 diverted flights on Friday, with Denver, Chicago, Los Angeles, and Cleveland among the airports taking on additional aircraft. Canadian hubs sit directly under the heaviest transatlantic and transborder flows, so they absorb diversions early. In plain terms: Canada's stops are a buffer against congestion, not a second outage.

For airlines, the cost math is already steep. The FAA's action has no announced end point, and by Friday evening the delay count — 10,500 and climbing — exceeded the cancellation count, which usually means carriers are still trying to operate rather than reset their schedules. Airlines that reset early typically recover faster and rebook passengers sooner.

What does this mean for travel sellers?

Every transborder itinerary touched by this event now carries rebooking workload, and Toronto and Montreal are the two busiest Canada-US gateways. Agents and OTAs should expect waiver-driven reissues, hotel night extensions from stranded passengers, and pressure on inventory in diversion cities on both sides of the border.

NAV CANADA's framing — systems normal, stops precautionary — suggests Canada's airspace itself is not the constraint. The constraint is gate and ramp capacity at two hubs suddenly parking aircraft they didn't schedule. If Toronto's 60%-plus extension probability holds, Saturday's transborder schedule is at risk too.

No party has yet said when either the US ground stop or the Canadian pauses will lift, so expect another wave of cancellations and diversions to be announced as Friday's operational picture firms up.