Air Canada and its unionized flight attendants remained at odds on Friday, despite government pleas for both sides to return to bargaining to avert a strike that would upend travel for tens of thousands of passengers.

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 the two sides to return to the bargaining table.

Air Canada began canceling flights Thursday ahead of a possible strike by its flight attendants that could impact hundreds of thousands of travelers. A complete shutdown of the country's largest airline threatens to impact about 130,000 people a day.