If you bring a hungry, cranky baby onto a plane, you should be ready to be the target of glares and grumbles. Your munchkin and your fellow passengers don't have to suffer just because the Transportation Security Administration, or TSA, has airtight rules about bringing liquids on board, but you won't be allowed to carry unlimited water through security. No restriction, however, will prevent you from getting your baby all the formula he needs.

Formula Rules

The TSA has tried to make things easy for parents flying with infants, but you're still subject to rules when flying with liquids. According to the TSA's policy, you're permitted to bring as much milk, formula or juice in your carry-on as your child could reasonably need for the flight. So while ready-to-feed formula is allowed through security in amounts larger than 3.4 ounces -- the maximum size container the TSA usually allows for liquids, gels and aerosols -- you won't be permitted to carry bottles of water through the security checkpoint, even if you intend to use them to make formula. Any water you bring through the checkpoint must be in a container smaller than 3.4 ounces, and all your liquids, gels and aerosols have to fit in a single 1-quart plastic bag.

Gathering Supplies

Since you can't bring bottles of water through security, your formula options are limited. You could buy just enough ready-to-feed liquid formula to get your baby through the flight and go back to your normal powder formula once you land. You could also bring empty bottles through security and fill them from airport drinking fountains, but doing so could introduce all sorts of unknown bacteria into your baby's food. If you do decide to bring powdered formula, buy room temperature bottled water after you get through security. In a pinch, you can also ask a flight attendant for a sealed bottle of water on the plane, but never mix tap water from the plane's bathroom faucet into your child's bottle.

Preparing Formula

Mixing up your baby's formula in an airplane is tricky under the best of circumstances. If he's strapped to your chest or screeching into your ear, you'll be so frazzled the powder might end up on your grumpy neighbor. Make your life as easy as possible by planning ahead. Portion the correct amount of powdered formula into each bottle before you leave home, and pack the bottles near the top of your carry-on. Once you get through security and buy water, wash your hands thoroughly and mix up enough bottles to get your little one through the flight.

Feeding a Baby

Ideally, you'll feed your baby while still at the gate, in the hopes that he'll be content and sleepy by the time you board and will sleep through takeoff, keeping him oblivious to ear pain caused by changing pressure. If he's not ready to eat, then feeding him on the plane is fine too; grab a burp cloth out of your carry-on before sitting down so you don't have to disrupt him after he eats. Even if your little guy is used to having heated formula, try to get him to accept the bottle at room temperature. If he won't drink it, ask a flight attendant if you can get a mug or bowl of hot water to soak the bottle in, but never ask for a bottle to be microwaved. Bag all your empty bottles so you can wash them thoroughly once you arrive at your destination.