Yes, a 17-year-old can fly alone in Canada in 2026, and they are generally treated as an adult passenger. For domestic flights within Canada (on WestJet, Air Canada, or Porter), the mandatory "Unaccompanied Minor" service usually only applies to children aged 5 to 11. For those aged 12 to 17, the service is optional. This means a 17-year-old can check themselves in, pass through security, and board the plane without any airline supervision. However, if the flight is international (crossing into the US or overseas), it is highly recommended—and sometimes required by border agents—that the 17-year-old carries a Notarized Letter of Consent signed by both parents. This letter proves they have permission to travel across borders and helps prevent delays with Canada Border Services Agency (CBSA) or US Customs, who are hyper-vigilant about potential runaways or international child custody disputes.