More than 10,000 flight attendants are poised to walk off the job around 1 a.m. ET on Saturday, followed by a company-imposed lockout if the two sides can't reach an eleventh-hour deal.

Their union says one of its core demands, to receive pay for groundwork, is unlikely to be introduced in arbitration. The airline began canceling flights ahead of the potential strike.

The prospect of a systemwide work stoppage by Air Canada's unionized flight attendants loomed large on Friday with a strike deadline just hours away, despite a government plea for both sides to return to the bargaining table.