Regardless of age, all children need a valid passport for air travel to another country. The application process for children under the age of 16 needs to be completed in person. To fill out this application, at least one parents needs to appear.

For an 11-year-old, the need for a passport depends entirely on the destination and the mode of transport. If traveling internationally by air (e.g., from the US to Europe or the UK to Spain), a valid individual passport is mandatory for all children, including infants. There are no exceptions for age in international aviation. However, for domestic travel within a country (e.g., a flight from New York to California or Delhi to Mumbai), children under 18 generally do not need a passport or even a photo ID in many jurisdictions; they are usually covered by the parent's identification. In the United States, children under 18 do not need ID for domestic flights when traveling with a companion. For land travel within the Common Travel Area (UK and Ireland), a birth certificate is often sufficient for an 11-year-old. Since 2025/2026, many countries are moving toward digital IDs, but for crossing a sovereign border, a physical passport remains the "gold standard" and is usually the only document that will be accepted at immigration for a minor.