It's not possible to print an Air Transat boarding pass online. In most cities in Canada and the United States, Air Transat offers an online check-in option to passengers who print their e-tickets and will receive their boarding passes at the airport.
For airports that support an online check-in, an e-ticket can be generated and downloaded up to 30 days before departure. Once the e-ticket is presented at baggage drop-off at the airport, travelers receive a boarding pass. The service of online check-in is not available at all airports. Air Transat allows online check-in at most airports in Canada and the United States, but the service is only available at select international destinations.