TORONTO (AP) — Air Canada said Tuesday it will gradually restart operations after reaching an agreement with the union for 10,000 flight attendants to end a strike.

Air Canada reached a deal with flight attendants to end a three-day walkout that led to mass cancellations during the busy summer season and forced country’s largest airline to withdraw its financial outlook for this year.

Air Canada said it will gradually begin restarting operations, but warned that complete restoration of operations could take up to a week.