WestJet Airlines has started parking 737 jets as it awaits a Sunday deadline for a possible strike by flight attendants. Find out more.

The clock is ticking down toward a strike deadline that could see 4,400 WestJet flight attendants hit the picket line as soon as Sunday.

The Canadian Union of Public Employees Local 8125 gave the airline notice early Thursday morning, the union said in a post on its website.