The airlines have agreed put each other’s codes on flights and offer a single ticket with through-checked bags on connections from early 2022. 

Under the agreement, WestJet’s code will be placed on Air Transat flights to some cities in Europe and Air Transat’s code will be on select WestJet flights in North America to enable both carriers to offer connecting transatlantic itineraries.

However, regulators must first approve the agreement and there may be competition law issues. 

"We are very excited to join forces with WestJet in what I am sure will be a successful collaboration, said Annick Guerard, Transat president and chief executive. 

“This agreement is a first milestone in our strategy to grow and strengthen our network through alliances. It will create great opportunities for our existing and future customers, who are looking to connect between North America and Europe and will enhance our long-standing presence on the transatlantic market."

Ed Sims, WestJet president and chief executive, added: “Confidence in travel is building and this new transatlantic cooperation will allow WestJet to offer even more destinations to travellers, connecting North America and Europe in new ways, and benefiting guests on both sides of the Atlantic.”