In 2026, a 12-year-old can fly on virtually any major commercial airline, but the specific rules regarding whether they are considered an "Unaccompanied Minor" (UM) vary. Most U.S. carriers, including Delta, United, and American Airlines, allow 12-year-olds to fly alone as "young adults." At this age, the specialized UM service—which involves staff escorts and supervised waiting areas—is typically optional rather than mandatory. However, some international carriers or specific budget airlines like Southwest may still require or offer different layers of supervision until the child turns 15. If the UM service is waived, the 12-year-old is responsible for navigating the airport and gate changes independently. It is crucial to check the specific "Unaccompanied Minor" fee and age brackets for your chosen carrier, as some airlines (like Frontier) have stricter policies and may not allow children under 15 to fly without an adult at all. Always ensure the minor has a government-issued ID or a copy of their birth certificate and a fully charged phone with emergency contacts saved.