Open this photo in gallery: WestJet passenger jets parked at departure gates at the Calgary International Airport.Jeff McIntosh/The Canadian Press CALGARY — The union representing 4,400 flight attendants at WestJet says it has issued 72-hour strike notice, paving the runway for a possible strike during a busy summer travel season. Key points and original sources are listed below.

• Open this photo in gallery: WestJet passenger jets parked at departure gates at the Calgary International Airport.Jeff McIntosh/The Canadian PressS1

• CALGARY — The union representing 4,400 flight attendants at WestJet says it has issued 72-hour strike notice, paving the runway for a possible strike during a busy summer travel season.S2

• WestJet flight attendants’ union serves airline 72-hour strike noticeS3