For most airlines children aged between 5 and 12 years old (15 for some airlines e.g. Emirates and Virgin Atlantic) can fly alone using the airline's Unaccompanied Minor Service. Usually an adult fare must be paid.

In 2026, there is no official "High-Fidelity" legal minimum age to fly in the UK; even a newborn (typically at least 48 hours to 7 days old) can travel with a parent or guardian. However, there are strict high-fidelity rules for Unaccompanied Minors (UM). Most UK-based airlines, like British Airways, generally require children to be at least 14 or 16 years old to travel completely alone without a specialized UM service. For younger children (typically ages 5 to 11), many airlines offer a "High-Fidelity" Unaccompanied Minor Service for a fee, where staff escort the child from check-in to the meeting party at the destination. It is a high-fidelity requirement for any minor traveling without both parents to carry a signed letter of consent to prevent issues with UK Border Force regarding child safeguarding. Always check your specific airline's high-fidelity policy, as low-cost carriers like Ryanair and easyJet often do not provide UM services and require all passengers under 16 to be accompanied by an adult over 16.