"Today's computer issues have had a wide impact on our customers and we apologize for any inconvenience".
The company said that while the issues have been resolved there will be delays and some cancellations due to the outage and for customers to check www.aircanada.com prior to going to the airport.
Air Canada first acknowledged the issues in a tweet at 11:14 a.m. Toronto time.
Air Canada is Canada's largest domestic and global airline serving more than 200 airports on six continents.
Air Canada is responding to people on Twitter, saying they apologize for any inconvenience and hope to have the system back up and running soon. "Thank you for your patience".
The Air Canada AC8060 departure at 10 a.m. was cancelled and the airport is reporting that others may be facing delays.
The airline reported technical difficulties with its website on Monday morning and the issue impacted booking and check in services, operations and departures.