Air Canada cabin crew walked off the job early Saturday, grounding hundreds of flights and stranding thousands of passengers forced to seek alternatives or stay put.

Air Canada suspended all operations Saturday morning after more than 10,000 flight attendants walked off the job demanding higher pay and better scheduling protections.

A bitter contract fight between Canada’s largest airline and the union representing 10,000 of its flight attendants escalated Friday as the union turned down the airline’s request to enter into gover...