Yes, a 15-year-old can fly on Aer Lingus alone, as the airline permits "unaccompanied young passengers" between the ages of 12 and 15 to travel on their own. However, Aer Lingus does not provide a formal "Unaccompanied Minor" (UM) escort service for this age group. This means the 15-year-old will be treated as an adult passenger and must be capable of navigating the airport and boarding process independently. A crucial requirement is that a Form of Indemnity must be signed by a parent or legal guardian at the airport check-in desk in the presence of an Aer Lingus staff member. This form acknowledges that the airline bears no parental responsibility and that the teen is traveling as an adult. For international flights, the teen must also possess a valid passport. It is important to note that Aer Lingus strictly prohibits children under 12 from traveling alone; they must be accompanied by someone who is at least 16 years old. If you are booking a flight for a 15-year-old, ensure you arrive at the airport early to complete the mandatory paperwork before they proceed to security.