American Airlines and Canada’s WestJet to Begin Interline Agreement CheapOair Staff October 20, 2010 general American and WestJet to work closely together American Airlines and Canada's WestJet Airlines announced Tuesday that they have partnered up in what is being called an interline agreement. Under the deal AA and WestJet passengers who switch flights between countries will be able to purchase a single ticket and check bags just once. The idea is to make travel much easier for customers. American said customers will now be able to connect with 25 new Canadian cities that are currently not offered via the airline thanks to working with WestJet. Connections will start to Calgary, Montreal, Toronto, Vancouver, Halifax and Ottawa. American and WestJet plan to expand their interline agreement later this year.