After a failed attempt in 2015, WestJet pilots are again seeking to form a union, this time under the umbrella of the Air Line Pilots Association, an international union that also represents pilots at Air Transat and Jazz Aviation.

The ALPA officially started its drive at WestJet in December of 2016, after many months of laying the groundwork. WestJet pilots tried to start an in-house union in the summer of 2015.

But it failed, with 55 per cent of pilots voting against certification.

Since then, the airline has launched long-haul flights to Europe and will launch an ultra low cost carrier, similar to Europe's Ryanair, or Spirit Air in the United States

It says pilots at WestJet filed membership cards with the Canada Industrial Relations Board on Thursday. In order to do that, at least 40 per cent of the pilot's group has to sign a union card.  

A secret ballot vote is then held, after the cards are certified. That is expected to happen in May.

With files from the Canadian Press