The dominant air carrier in Canada set in motion a process that could ground 130,000 passengers a day by Saturday.

Air Canada said it would reach out via email or text to let customers know if their flights are canceled. The cancellations on Thursday included some long-haul overseas flights. By the end of Friday, the airline expects to cancel 500 flights.

TORONTO — Air Canada started canceling flights on Thursday ahead of a possible work stoppage by 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.