Most U.S. airlines will permit children who have reached their fifth birthday to travel unaccompanied. Kids ages 5 through 11 who are flying alone must usually travel pursuant to special “unaccompanied minor” procedures. On some airlines, these procedures are required for unaccompanied children as old as 14.

For international travel in 2026, most major airlines require a child to be at least 5 years old to fly alone as an "Unaccompanied Minor" (UM). Children under 5 are strictly prohibited from flying without an adult aged 18 or older. For those aged 5 to 11 (and sometimes up to 14 or 15 depending on the airline), the Unaccompanied Minor service is mandatory. This service involves a dedicated staff member escorting the child through security, supervising them during the flight, and handing them over to a pre-authorized adult at the destination. For teenagers aged 12 to 17, the service is usually optional, and they may be allowed to fly as "Young Passengers" without formal supervision. It is important to note that many international carriers (like British Airways or Lufthansa) have eliminated UM services on certain routes or have specific age caps. Additionally, international UM fees in 2026 typically range from $100 to $200 per leg, and parents must report to the airport 3 to 4 hours early to complete the extensive "Flying Solo" legal documentation required for cross-border travel.