When Air Canada pilots went on strike in September 1998 for 13 days, all of the carrier's more than 600 daily flights were grounded, stranding passengers and costing the airline C$133m ($96m; £71m) before a negotiated deal was reached.

About 200 Air Canada flights are to the U.S., according to The Wall Street Journal. The strike comes as Canadians increasingly avoid the United States because of diplomatic tensions between the neighbors. With more Canadians taking vacations at home, Air Canada has seen extra pressure on domestic routes.