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 union representing 10,000 flight attendants for Canada's largest airline issued issued a 72-hour strike notice on Wednesday.

Air Canada has canceled most of its flights over the next few days to prepare for a strike by flight attendants. Some travelers may end up stranded as a result.