Air Canada's flight attendants were poised to strike on Saturday as the carrier cancelled hundreds of flights impacting more than 100,000 passengers ahead of a threatened work stoppage that could shut down service.

Summer travelers are facing uncertainty as the clock winds down on a possible strike by Air Canada flight attendants, which the airline said would force it to cancel almost all of its scheduled flights as soon as Saturday.

More than 10,000 Air Canada flight attendants went on strike as of 12:58 a.m. ET on Saturday, after the airline and the union representing them failed to reach a deal ahead of the deadline.