you have to also understand the relationship between most of those European airlines and Sunwing Airlines. TUI AG that owns the TUI airlines also has a 49% share of Sunwing Vacations and Sunwing Airlines, hence the benefit to the European business in being able to utilise the aircraft and crew in winter by sending them to Canada.
In addition, in the summer, a couple of SWG aircraft operate for Thomson out of the Republic of Ireland with SWG pilots and Thomson cabin crew.