"Three routes will be temporarily suspended between Montreal and Pittsburgh, Baltimore and Kelowna and one from Toronto to Fort McMurray," Fitzpatrick said.

Fitzpatrick said "most" flights affected by the changes are out of its Toronto and Montreal hubs.

"These will be mostly frequency reductions, affecting primarily evening and late-night flights by smaller aircraft, on transborder and domestic routes," he said.

But he said "international flights are unaffected, with a few timing changes to reduce flying at peak times and even out the customer flow."