When traveling internationally, it's a good idea to get a consent letter from the parents indicating that you have their permission to travel with your grandchildren. Most likely no one will ask you for it, but you'll be glad to have a hard copy on you in a scenario where you can't get in touch with them.

Grandparents can certainly fly with their grandchildren, but it is highly recommended—and sometimes legally required—to carry specific documentation to ensure a smooth journey. For domestic flights within the United States, airlines generally do not require identification for children under 18, but they do require the accompanying adult to be able to verify the child's age if they are flying as a lap infant. For all travel, especially international trips, grandparents should carry a notarized Minor Travel Consent Form signed by both of the child's parents or legal guardians. This document grants the grandparents permission to travel with the minor and is crucial for preventing concerns regarding parental child abduction at border crossings. Additionally, it is vital to carry a Medical Consent Form, which authorizes the grandparents to make medical decisions or seek treatment for the child in case of an emergency. Bringing copies of the child's birth certificate and health insurance cards is also a "best practice" to ensure you are prepared for any bureaucratic or medical situations that may arise while away from the parents.