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.

The Canadian carrier said it expects to call off 500 flights by the end of Friday. Air Canada said it was suspending its schedule and trying to get passengers booked with other airlines to limit disruptions.

Preparations for the looming walkout and the airline's planned weekend lockout of its flight attendants began Thursday with multiple flight cancellations as part of what Air Canada described as a “phased wind down” of most operations.

Both the union that represents about 10,000 Air Canada flight attendants and the airline say disagreements over key issues, inc

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