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 on Thursday began what it described as a “phased wind down” of most operations that included multiple flight cancellations. Air Canada said it was suspending its schedule and trying to get passengers booked with other airlines to limit disruptions if members of its cabin crews walk off the job.

See Full Page