Air Canada said it will gradually begin restarting its operations after strike action grounded its flights since August 16. It said the first flights are scheduled for Tuesday evening, but that it could take seven to ten days to restore its full service, and that some flights will be cancelled during that period.

The union for Air Canada's 10,000 flight attendants said early Tuesday that it has reached a tentative agreement to end a strike.

The Canadian Union of Public Employees, which represents Air Canada's 10,400 flight attendants, wanted to make gains on unpaid work that go beyond recent advances secured by their counterparts at U.S...