Yes, a 17-year-old can travel with a 14-year-old, but they are generally treated as two separate minors by most airlines rather than an adult accompanying a child. In the aviation industry, the "adult" threshold for accompanying a minor is typically 18 years old. Since the 17-year-old hasn't reached that age, the 14-year-old is often classified as an Unaccompanied Minor (UM). Some airlines make the UM service mandatory for children up to age 14 or 15, while for a 17-year-old, it is usually optional. This means you may be required to pay the Unaccompanied Minor fee for the 14-year-old and complete the necessary paperwork, even though they are traveling together. Policies vary significantly by carrier—for example, some budget airlines do not allow anyone under 16 to fly without someone 18 or older—so it is vital to check the specific "Minor Travel" section of your chosen airline's website before booking.