Every airline has a different cancellation policy dependent on the distance, destination, and travel time. The cancellation policy at Air Canada is its own. According to Air Canada cancellation policy, you may postpone your flight and get a full refund in the following cases:

Air Canada has cancelled your flight.
You planned your trip and made your ticket reservations before April 30, 2021.
You choose to revoke your ticket within 24 hours of purchasing it.
You've paid for a completely flexible fare.
You were prevented from boarding even though your reservation was confirmed.
There have been at least three hours of delays for your flight.
You miss your connecting connection as a result of Air Canada rescheduling your flight.
If you have a specific emergency (such as a death, serious illness, military orders, etc.) you won't be able to make it to your flight (subject to Air Canada's discretion).

Read also : Alaska Airlines cancellation policy | Allegiant Airlines cancellation policy