Calgary-based WestJet and the Canadian Union of Public Employees have reached a tentative deal, ending a strike that has led to the cancellation of hundreds of flights, both sides said early Monday.

Thousands of passengers could be forced to suspend or change their travel plans during the August long weekend.

WestJet says it's still bargaining with flight attendants in hopes of a deal, but the company is beginning to keep planes on the ground as a "necessary measure" to protect…