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.

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.