If children are not travelling with both their parents, (ie: if they are travelling alone, or with another adult), this form can be used to give permission. A notarized letter of consent is a crucial requirement when traveling with minors without both parents or guardians.A child travel consent form is strongly recommended if a child travels alone, with only one parent or an authorized adult. See what documents a child needs to travel to or from the US alone or with a parent or relative. Non-US citizen children traveling to the US. Child travel consent forms establish legal permission for a child to travel with an adult other than their parents. The most common interpretation is that the traveling parent requires a notarized letter something not found in any custody order.