After peaking at record heights in 2018, the number of passengers passing through Canada’s airports has started falling back to Earth, with several major airports reporting flat or falling volumes through the busy summer months.

Data being reported by the country’s largest airports suggest a significant percentage will have a hard time matching explosive growth over the past few years. And for some, high hopes for another record-breaking summer season turned to disappointment.

There is no question it has been a difficult summer in aviation. The ongoing grounding of the Boeing 737 Max has removed more than 30 planes from Canadian skies and forced airlines to suspend services and juggle their schedules to make up the shortfall. There is no indication when the type might be allowed to fly again.

Air Canada, which will report its summer financial results later this month, expected the full impact of the grounding to hit home during the peak travel season, and preliminary data suggests their fears may be borne out. This week, the airline announced its 24 Max aircraft would not return to service until at least Valentine’s Day.

Edmonton International Airport reported its third quarter data Thursday, showing passenger numbers so far this year are down an anemic 0.6% from the same time in 2018. But the data hide a greater concern in July, August, and September, when traffic fell a whopping four per cent from the summer 2018.

In an internal note published in June, airport officials blamed the falling numbers on a number of factors, including Flair changing its business model, and moving away from hub operations in Edmonton, Westjet reducing capacity in the Alberta capital, despite the addition of flights from its Swoop subsidiary, and Delta dropping flights to Seattle.

A similar story is playing out on the West Coast in Victoria, where passenger numbers are down almost six per cent from last year. The airport has seen a reduction in some domestic services, and U.S. carriers Delta and United both dropped service to the British Columbia capital.

Any change in passenger numbers can have a significant effect on an airport. Fees charged to airlines based on the number of passengers accounted for well over half the budget at Canadian airports last year, and Airport Improvement Fees contribute more than a billion dollars a year to airport infrastructure.

Canada’s four hub airports have largely been spared the pain, the data suggest, though even they are showing signs of struggle.

Vancouver has struggled the most, with passenger numbers dipping 1.2% in August as traffic to Asia-Pacific countries felt the squeeze of trade and political tensions.

Even Canada’s largest airport, Toronto Pearson, has felt the squeeze. Passenger traffic in July, the most recent month available, was flat, despite posting an impressive 2.6% gain in the first seven months of the year.

Montreal, led by an explosion in international traffic, has posted an impressive 4.8% growth through the end of August, though even that solid growth hid a slight dip in domestic traffic in August.

In Calgary, where the launch of Westjet Dreamliner flights to London, Paris, and Dublin led to a roughly 20% surge in traffic to Europe this summer, traffic has grown 3.6% through the end of August, though domestic flights attracted almost two per cent fewer passengers in August.

Correction: A previous edition mistakenly reported that Montreal’s traffic numbers were reported through the end of September. They have in fact reported to the end of August.