Children do not need a birth certificate to fly. It doesn't hurt to be prepared, especially if it’s your first time traveling with a child.
While the rules for adults traveling either domestically or internationally are pretty straightforward, it gets a bit more confusing when you're dealing with minors, or those under 18 years of age, since they don't always have driver's licenses, valid passports or other forms of photo ID to show upon check-in. When you're headed on a trip with a child, there are some general rules of thumb that will help you fly with little hassle, but in general, children do not need a birth certificate to fly. Still, it doesn't hurt to be prepared, especially if it’s your first time traveling with a child.
If you've flown a lot in the past, you know that airlines' policies can vary greatly, and it's no different for flying with kids. When you book your flight, ask your reservations agent what the policy is for flying with children and what type of travel documentation the airline requires. If you booked online, call the airline's customer service line to inquire about the rules. Be sure to mention your child’s age, in case there are rules for specific ages. In many cases, a birth certificate is all you'll need but it depends on where you're going. Regardless, everyone needs to show some form of personal identification to receive a boarding pass.
According to the Transportation Security Administration, people 18 and over are required to show a state- or federal-issued form of identification when they get to the TSA security checkpoint. While this rule does not apply to those under 18, the general rule for children seems to be to carry the child’s birth certificate with you, in case you are questioned about the child's identity.
No matter a person's age, if you're flying across borders, you will need a passport. While there are some exceptions for traveling over land in certain countries, there are no exceptions for air travel. If your child does not have a passport for your international travels, be sure to give yourself plenty of time to get one before your trip.
If you're traveling with your child and you're the only parent on the trip, it's a good idea to carry some kind of documentation stating that the other parent gives you permission to travel with the child. A template for a "Consent to Travel" form is available on the FamilyTravelForum website. The letter should be written and signed by the non-traveling parent, stating that she gives permission for the child to travel domestically or abroad. Since each airline has different policies, it's a good idea to contact the individual airline you're traveling with to find out whether this parental consent letter needs to be notarized and if there are other requirements for the trip.
Note: When traveling with infants and toddlers, you can check strollers and car seats. You are also able to bring necessary items like breast milk in your carry-on bag. As for seating, you may keep your child on your lap if they are of lap-child age, but the Federal Aviation Administration (FAA) states that it is safest if the little ones have their own seat and seat belts, accompanied by a safety seat approved by the FAA. Only one lap-child is permitted per adult. If your little one is sitting in their own seat, you must pay for that ticket.