Yes, a minor can fly with a sibling, but the specific rules depend on the ages of both children and the airline's "Unaccompanied Minor" (UM) policy. Generally, if the older sibling is at least 16 to 18 years old (depending on the carrier), most airlines consider them an "adult" for the purpose of supervising a younger child. In this scenario, the younger child does not need to be enrolled in the UM program. However, if both siblings are under 15, many airlines—including major U.S. carriers like Delta and United—will require them to be enrolled in the Unaccompanied Minor service, which involves a fee and specific drop-off/pick-up protocols at the airport. In 2026, some international airlines have stricter age requirements, requiring the supervisor to be at least 21. It is critical to carry a "Consent to Travel" letter signed by the parents, especially for international flights, to prove that the siblings have permission to travel together. This letter should include contact information and details about the trip. Always check the "Minor Travel" section of your specific airline's website, as "Budget" carriers like Ryanair often have different age thresholds than full-service airlines.