In 2006 the Transportation Security Administration (TSA) enacted new carry-on luggage restrictions, on the heels of failed bombing attempts on transatlantic flights with the use of liquid explosives thought to be hidden in soda cans. At the time of publication, liquids are restricted to containers carrying no more than 3.4 ounces. An exception is in place for baby formula.

TSA Rules

The 3-1-1 law for carry-on luggage limits airline passengers to containers of 3.4 ounces or smaller, with all containers fitting inside a single 1-quart plastic bag. This limit does not apply to formula or other items used for feeding infants. According to TSA policy, you may pack as much prepared formula in your carry-on as you want; however, you are encouraged to carry only as much formula as you think you'll need. Liquids are not limited in checked bags, but formula should be made as close to feeding time as possible.

Preparing at Home

It's your choice whether to prepare formula at home or wait until you're on the plane. If you opt for the former, make bottle preparation your last step before leaving for the airport; prepared formula should be stored for no more than one hour at room temperature or 24 hours in the fridge, says Make enough bottles to last 50 percent longer than you think you'll need and tuck them into a soft-sided cooler bag with frozen ice packs. If you prefer to make fresh formula on the plane, measure powdered formula into each bottle and screw the lid on tightly. Disposable bottles and liners are convenient.

Going Through Security

Liquids that conform to the TSA's 3-1-1 rule go through the X-ray scanner along with other carry-ons, but formula in larger quantities requires additional screening. As soon as you arrive at the security checkpoint and begin loading your items onto the conveyor belt, tell the closest agent that you're carrying formula and ice packs, and pull out the bag holding them. These items will probably be taken out of their bag and examined by hand. If you're carrying bottles containing only formula powder, they should not require special screening; you may keep them in your carry-on, though it's always wise to keep these bottles near the top of your bag in case an agent does want to examine them.

Feeding Your Baby

Formula requires water. Buy a bottle or ask a flight attendant for a sealed bottle. In the airport you may want to fill the bottle from a drinking fountain, but measuring the correct amount of water may be tricky in a cramped sink, and the spout of the fountain may host germs. Don't risk using the water in an airplane bathroom; some tests have found disease-causing organisms in this water, reports "The Wall Street Journal." If your infant won't drink cool or room-temperature formula, ask a flight attendant if she can warm a filled bottle by running it under hot water. For greater convenience, consider bringing a nonelectric portable bottle warmer or pocket heat packs to wrap around the bottle.