The most contentious issue in the contract negotiations has been the union's demand for compensation for time spent on the ground between flights and when helping passengers board.

More than 10,000 Air Canada flight attendants went on strike after a deadline to reach a deal passed, the union confirmed early Saturday.

The CIRB directed Air Canada to resume airline operations and for all Air Canada and Air Canada Rouge flight attendants to resume their duties by 2 p.m. ET (1800 GMT), the airline said.